WO2008094838A2

WO2008094838A2 - Apparatus and methods for electrochemical processing of wafers

Info

Publication number: WO2008094838A2
Application number: PCT/US2008/052104
Authority: WO
Inventors: Daniel J. Woodruff; David P. Mattson; Paul R. Mchugh; Gregory J. Wilson; James J. Erickson
Original assignee: Semitool, Inc.
Priority date: 2007-01-29
Filing date: 2008-01-25
Publication date: 2008-08-07
Also published as: TWI384095B; WO2008094838A3; TW200835819A

Abstract

In an apparatus for electrochemically processing wafers, a supplemental virtual electrode counteracts an electric field offset relative to the wafer resulting from misalignment between the wafer and the anode in the vessel. The apparatus may include an agitator having an elongated agitator element(s) with each end attached to a support. A motor is coupled to one support drives the agitator along a linear path. A linear guide is engaged with the other support to guide the motion of the agitator. A robotic in a processing system Includes a position sensor located to identify a rotational orientation of the wafer while the wafer is carried by an end effector on the robot. The rotational orientation of the wafer is corrected by appropriately moving artlculatable links of the robot device, and/or by rotating a rotor support holding the workplece for processing at a process chamber.

Description

APPARATUS AND METHODS FOR ELECTROCHEMICAL

PROCESSING OF WAFERS

PRIORITY CLAIM

[0001] This application claims priority to United States Patent Application numbers 11/699,768, 11/699,762, 11/699,763 and 11/700,263, all filed January 29, 2007, and all incorporated herein by reference.

TECHNICAL FIELD

[0002] This application relates to apparatus and methods for handling and processing semiconductor wafers and similar substrates.

BACKGROUND

[0003] Microelectronic devices, such as semiconductor devices, imagers, displays, storage media, and micromechanical components, are generally fabricated on and/or in wafers using processes that deposit and/or remove materials from the wafers. Electroplating is one such process that deposits conductive, magnetic or electrophoretic layers on the wafers. Electroplating processes, for example, are used to form copper interconnects or other sub-micron features on wafers. Electropolishing is another process that removes material from a wafer.

[0004] One challenge of plating materials into narrow, deep recesses is that it is very difficult to completely fill the very small features and create a desired surface profile on the plated layer (e.g., uniformly planar, domed, etc.). For example, as the performance of microelectronic products increase, the aspect ratios and densities of the recesses substantially increases. To adequately fill such small, high density recesses with high aspect ratios, existing plating practices often plate a metal onto a very thin seed layer or directly onto a barrier layer. Thin seed layers and barrier layers, however, typically have relatively high resistances that cause a significant drop in current density from the edge of the wafer to the center during the initial stages of a plating cycle. The plating rate at the edge of the wafer is accordingly significantly higher than the center during the initial portion of the plating process, which causes the plated material at the edge of the wafer to be substantially thicker than the middle. This edge effect is further exacerbated by the higher densities and higher aspect ratios of the recesses. Therefore, reducing or eliminating the edge effect is a significant challenge.

[0005] Several existing plating reactors use a current thief electrode attached to the wafer holder to mitigate the edge effect caused by high resistance of the wafer or by the geometry of the chamber. The thief electrode modifies the electric field in the perimeter region of the wafer, and reduces the plating rate at the perimeter of the wafer to compensate for the edge effect. Although such systems may mitigate the edge effect, they also have several disadvantages, including particle generation and maintenance factors.

[0006] Other types of systems have a plurality of anodes, a thief electrode separate from the wafer holder, and a virtual thief electrode defined by an aperture having a fixed size under the wafer. Such systems with detached thief electrodes generally position the thief electrode in the bottom portion of the reactor vessel. With these systems, dislodged particles from the thief electrode are not as likely to plate onto the wafer because thief electrode is not as close to the wafer. However, they tend to be sensitive to misalignment between the wafer holder and the thief electrode or the anode(s). Such misalignment can lead to a side-to-side non- uniformity of the film plated onto the wafer, and is particularly problematic in systems in which the wafer is held stationary during processing (e.g., plating a magnetic alloy). This is not as problematic in systems in which the wafer is rotated during processing because any side-to-side non-uniformity can be average out, which greatly reduces the sensitivity of the system misalignment. Another disadvantage of having the thief electrode located in a lower portion of the chamber, is that the chambers need to be drained and partially disassembled to access the thief electrode for cleaning.

[0007] Accordingly, apparatus and methods are needed to reduce non- uniformities caused by an offset between the wafer holder and the vessel, to reduce particle contamination associated with thief electrodes, and to make it easier to clean and maintain thief electrodes.

[0008] In many wet chemical processes, a diffusion layer forms adjacent to a process surface of a workpiece (e.g., a semiconductor wafer). The mass-transfer in the diffusion layer is often a significant factor in the efficacy and efficiency of wet chemical processing because the concentration of the material varies over the thickness of the diffusion layer. It is accordingly desirable to control the mass- transfer rate at the workpiece to achieve the desired results. For example, many manufacturers seek to increase the mass-transfer rate to increase the etch rate and/or deposit rate, thereby reducing the time required for processing cycles. The mass-transfer rate also plays a significant role in depositing alloys onto workpieces because the different ion species in the processing solution have different plating properties. Therefore, increasing or otherwise controlling the mass-transfer rate at the surface of the workpiece is important for depositing alloys and other wet chemical processes.

[0009] One technique for increasing or otherwise controlling the mass-transfer rate at the surface of the workpiece is to increase the relative velocity between the processing solution and the surface of the workpiece, and in particular, the relative velocity of flows that impinge upon the workpiece (e.g., non-parallel flows). The velocity of processing fluid may be increased using fluid jets, by rotating the workpiece, or with paddles that translate or rotate in the processing solution adjacent to the workpiece to create a high-speed, agitated flow at the surface of the workpiece. The paddle typically oscillates between the workpiece and an anode in the plating solution. Single paddle designs require fast paddle movement, resulting in high loads. Cantilevered paddle designs make maintaining consistent paddle spacing difficult. However, driving a single paddle from both ends can cause binding if the drive mechanism is not precisely synchronized.

[0010] Arrays of paddles have also been used. Typically a paddle array is carried at one end and cantilevered across the diameter of the workpiece. The paddle array can be reciprocated over a much shorter stroke than a single paddle while still providing suitable agitation adjacent to the workpiece. However, in some cases, the cantilevered arrangement of the paddle array results in some parts of the paddles (e.g., those near the supported end of the array) maintaining a closer spacing relative to the workpiece than are other parts of the paddles (e.g., those near the unsupported, cantilevered end of the array).

[0011] Accordingly, apparatus and methods are needed for agitating the processing solution adjacent to a workpiece in a way that provides consistent spacing between the agitator and the workpiece, and that does not require high agitator speeds and/or extended agitator movement.

[0012] In automated processing systems, workpieces or wafers are moved using robots. The wafers typically have a notch or flat edge that identifies the crystal plane orientation of an individual workpiece. Some processes are orientation- dependent, including at least some processes in which magnetic materials are applied to or removed from the workpiece. In such cases, the workpiece must have the proper rotational orientation in the processing chamber when the orientation- sensitive process is performed. A pre-aligner is typically used to rotationally orient the workpiece. The pre-aligner includes a sensor that detects the location of the notch, and a chuck or other device that rotates the workpiece to the proper rotational orientation.

[0013] In many cases, the pre-aligner is located at a dedicated pre-aligner station in the processing system. Workpieces are transferred directly from the load/unload station to the pre-aligner station before undergoing any other processes at the tool. One drawback with this approach is that the workpiece may become misaligned as a result of being gripped and released multiple times at multiple process stations prior to reaching the station where the rotational orientation of the workpiece is particularly significant. For example, the workpiece may undergo a pre- wet process, a plating process, and a spin/rinse/dry sequence prior to undergoing deposition of magnetically-sensitive materials.

[0014] One approach to this problem is to transport the workpiece back to the pre-aligner station immediately prior to undergoing the orientation-sensitive process.

However, this takes time. Furthermore, if the workpiece is wet as a result of the immediately foregoing process, it typically must be dried before being handled by the pre-aligner, which takes additional time, and further reduces the rate at which workpieces are processed.

[0015] Accordingly, an apparatus and methods are needed for quickly and efficiently adjusting or correcting the rotational orientation of a workpiece prior to conducting a process on the workpiece that is sensitive to the rotational orientation.

[0016] In some electroplating processes, it is desirable to expose the material being deposited on the workpiece to a magnetic field that orients the material in a particular direction relative to coordinates of the workpiece. For example, it is desirable to plate a ferromagnetic material on the workpiece with a uniform magnetic orientation when the workpiece is to be used for computer hard drive components. It is important in such cases to orient the ferromagnetic material properly with respect to the workpiece by placing a strong magnet near the process chamber during the deposition process. However, the magnet can affect other devices and components of the system. In addition, the chemicals used in the system may have potentially harmful effects on the magnet.

[0017] Accordingly, it would be advantageous to shield the magnets in the system. It would also be advantageous to do so without having a significant effect on other components of the system, and without significantly increasing the size of the system.

BRIEF STATEMENT OF THE INVENTION [0018] To overcome the problems and challenges of existing thief electrode designs, the present apparatus uses the combination of a supplementary electrode and an associated supplementary virtual electrode to reduce particle contamination, reduce non-uniformities caused by wafer-anode misalignment, and provide better control of the edge effect associated with high density features. The supplementary electrode and the supplementary virtual electrode are configured to self-compensate for misalignment between the wafer holder and the counter-electrodes (or anodes). This is accomplished by, at least in part, forming an aperture that defines the virtual supplementary electrode using a portion of the vessel and a portion of the wafer holder. The shape of the aperture is related to the extent and orientation of the offset between the wafer and the anodes so that the aperture is narrower on one side where the wafer holder is closer to the supplementary electrode and wider on the other side where the wafer is further from the supplementary electrode.

[0019] Another feature that compensates for misalignment between the wafer holder and the electrodes is that the supplementary electrode is close to the supplementary virtual electrode. As a result, even small wafer-anode misalignments (e.g., 0.5-1.0mm) can produce relatively significant changes in the effect of the supplementary electrode on opposing sides of the wafer. Mechanical alignment to this accuracy is difficult across multiple chambers in a production environment. These features together or separately counteract non-uniformities associated with misalignment between the wafer holder and the vessel.

[0020] The apparatus and methods also provide easy cleaning of the thief electrode. This is accomplished by locating the supplementary electrode where it is separate from the wafer holder and above the vessel. The supplementary electrode can accordingly be removed from the chamber without having to disassemble significant portions of the vessel. Moreover, the supplementary electrode is positioned in the exit flow of the processing fluid outside of the processing zone such that particles from the supplementary electrode are entrained in the flow of the processing fluid downstream from the wafer. The particles can then be filtered before the processing fluid is recirculated back into the chamber. As a result, the upper location of the supplementary electrode and its position in the exit flow of the processing fluid provide easy cleaning and mitigate particle contamination.

[0021] The apparatus and methods further provide good control of the current density to enhance the uniformity or otherwise provide the desired surface profile on the plated layer. The apparatus accomplishes this, in part, by configuring the supplementary electrode, the supplementary virtual electrode, and the vessel so that the supplementary electrode is not limited by the chamber geometry and has a strong influence on the current density at the perimeter of the wafer. More specifically, the supplementary virtual electrode is located in the processing zone at least proximate to the edge of the wafer and the supplementary electrode is positioned close to the supplementary virtual electrode. Therefore, the current density and plating profiles can be controlled by dynamically changing the current to the supplementary electrode without having to change the physical geometry of the chamber.

[0022] This is particularly useful when plating different types of wafers in the same apparatus because the different perimeter characteristics of the different wafers can be addressed using the current applied to the supplementary electrode instead of having to change the shields or other components associated with the chamber geometry. The current density may be further controlled by using the configuration of the supplementary electrode and the supplementary virtual electrode in combination with a plurality of anodes and/or virtual anodes in the vessel. Positioning the supplementary virtual electrode in the processing zone at a location relative to the vessel where dielectric shields cannot limit the electric field of the supplementary electrode enables the supplementary electrode to have a strong influence on the current density in the periphery of the wafer. This allows the supplementary electrode to effectively control the current density in the periphery of the wafer. As such, it is easier to plate different types of the wafers in the present apparatus compared to existing systems in which control of the current density in the periphery of the wafer is limited by the geometry of the vessel.

[0023] An apparatus may further include, at least one counter electrode in the vessel that can operate as an anode or a cathode, depending upon the particular plating or electropolishing application, a supplementary electrode, and a supplementary virtual electrode. The supplementary electrode is configured to operate independently from the counter electrode in the vessel. The supplementary electrode can be a thief electrode biased at the same polarity as the wafer. The supplementary electrode can alternatively be a de-plating electrode for de-plating ring contacts between processing cycles, or the supplementary electrode can further be used as another counter electrode biased opposite the wafer during a portion of a plating cycle or polishing cycle. The supplementary virtual electrode is located in the processing zone, and it is configured to counteract an electric field offset relative to the wafer associated with an offset between the wafer and the counter electrode in the vessel when the wafer is in the processing zone.

[0024] The supplementary virtual electrode, more specifically, can have an aperture for shaping an electric field component from the supplementary electrode such that the aperture is formed, at least in part, by a portion of the vessel and a portion of a wafer holder in which the wafer is positioned. In operation, misalignment between the wafer holder and the vessel causes the aperture to have a first width at one side of the wafer holder and a second width different than the first width at an opposing side of the wafer holder. For example, the aperture can have a narrower width at the side of the vessel where the wafer holder is closer to the supplementary electrode compared to an opposing side where the wafer holder is further from the supplementary electrode. The narrower portion of the aperture reduces the effect of the supplementary electrode at that side, while the wider portion of the aperture increases the effect of the supplementary electrode at the opposing side. The different effect of the supplementary electrode on the different sides of the wafer holder self-compensates for the corresponding offset between the wafer holder and the counter electrode. As a result, the apparatus reduces non-uniformities associated with an offset between the wafer holder and the vessel when the wafer holder holds a wafer in the processing zone.

[0025] In an electrochemical processor, an improved agitator or paddle system provides a desired amount of liquid agitation at the workpiece surface, while maintaining consistent spacing between the agitator and the workpiece. The agitator has one or more elongated agitator elements, with a first support near to a first end of the agitator elements and a second support near to a second end of the agitator elements. A motor is coupled to the first support and not the second support to drive the agitator along a linear path relative to the process location. A linear guide is then engaged with the second support. By not driving the agitator from both ends, the likelihood for binding the agitator is reduced or eliminated. By providing a linear guide opposite the driven end of the agitator, the spacing between the agitator elements and the workpiece is maintained across the surface of the workpiece.

[0026] In some designs, the linear guide is positioned to (a) restrict movement of the agitator toward and away from the process location along a first axis, and (b) allow linear translation of the agitator along the linear path, which is aligned with a second axis generally perpendicular to the first. The linear guide can also (c) allow for movement of the agitator along a third axis generally perpendicular to both the first and second axes to at least reduce the tendency for the agitator to bind with the linear guide. For example, the linear guide can include a U-shaped channel having an upwardly facing opening, and the channel can carry rollers connected to the second support. At least one roller is positioned to be in contact with one of the walls of the channel, while another roller is not, thereby allowing for at least some motion along the third axis.

[0027] In operation, a processing fluid is directed upwardly into a vessel toward a workpiece positioned at a process location. The processing fluid is then directed radially outwardly adjacent to the workpiece and over a weir. The processing fluid adjacent to the workpiece is agitated with an agitator by driving the first support along the linear guidepath and guiding the second support without driving the second support. The motion of the agitator toward and away from the process location is at least restricted along the first axis, permitted along a second axis (e.g., a reciprocation axis) generally transverse to the first axis, and permitted along a third axis generally perpendicular to both the first and second axes at least to an extent that reduces or eliminates binding. [0028] For improved detection of wafer orientation, a robot for handling wafers in a processing system includes a base unit that is moveable along a guide path, and a carrier that is moveable relative to the base unit. The carrier includes an end- effector that engages the workpiece and moves it toward and away from the base. The transfer device further includes a position sensor located to identify a rotational orientation of the workpiece while the workpiece is carried by the end-effector. Accordingly, the transfer device need not include a separate support that holds the workpiece while identifying the rotational orientation of the workpieces. Instead, the same end-effector can carry the workpiece while it is transferred to and from processing stations, and while the rotational orientation of the workpiece is identified. In a particular arrangement, the end-effector has edge ghppers positioned to engage an edge of a workpiece. Accordingly, the rotational orientation of the workpiece can be determined at the transfer device, without requiring the workpiece to be supported centrally, e.g., with a vacuum chuck. This particular arrangement also eliminates the need to dry the workpiece prior to supporting it during detection of its rotational orientation.

[0029] The position sensor is operatively coupled to a controller (e.g., via a wireless or other communication link) to provide signals corresponding to the rotational orientation of the workpiece. The controller can compare the detected rotational orientation of the workpiece with a target value, determine a rotational orientation correction value, and direct a signal corresponding to the correction value.

[0030] The rotational orientation of the workpiece is updated or corrected in one or more ways. For example, the transfer device can move the workpiece to a support positioned proximate to a processing chamber, and the support can rotate the workpiece to its correct orientation and then carry the workpiece at the processing chamber during the ensuing process. In another arrangement, the transfer device includes multiple, articulatable links. The links are positioned in such a way as to properly orient the workpiece as it is handed off to the support so that once at the support, the workpiece has the proper orientation for processing. In both cases, the workpiece is rotationally oriented without the need for transferring the workpiece to a dedicated pre-aligner station, and without the need for a separate support that holds the workpiece while its rotational orientation is identified.

[0031] In an electrochemical processing system using magnets to magnetically orient materials applied to a wafer, an enclosure is positioned around the magnet to isolate the magnet from process chemicals, protecting the magnet. A magnetically conductive shield is positioned between the magnet and the motion path of the system robot or transfer device, to shield the transfer device from the magnetic field generated by the magnet. This protects the transfer device from interference by the magnet. The shield used to protect the transfer device may also provide a magnetically conductive return path that orients (e.g., straightens) the magnetic field within the process chamber to more consistently and reliably orient materials deposited on the wafer. Other components of the system may also be protected from the effects of the magnet. For example, motors used to drive an associated workpiece support (which carries the workpiece at the process chamber) can be shielded.

[0032] The invention resides as well in sub-combinations of the elements and steps described. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In the drawings, the same element number indicates the same element, in each of the views.

[0034] Figure 1 is a side view of a thief electrode design that can compensate for wafer misalignment.

[0035] Figure 2 is an enlarged view illustrating a portion of Figure 1 in greater detail.

[0036] Figure 3 is a cross-sectional view illustrating an operation of the design shown in Figure 1.

[0037] Figure 4 is a cross-sectional view illustrating another operation of the design shown in Figure 1.

[0038] Figure 5 is a schematic side view of a process chamber.

[0039] Figure 6 is a side view of another process chamber design.

[0040] Figure 7 is a cross-sectional isometric view of another design.

[0041] Figure 8 is a cross-sectional view of the design shown in Figure 7.

[0042] Figure 9 is a cross-sectional view of another design.

[0043] Figure 10 is a cross-sectional view of another design.

[0044] Figure 11 is a top isometric view of a system having one or more process chambers. [0045] Figure 12A is a cut-away view of one of the process chambers shown in Figure 11.

[0046] Figure 12B is a detailed, cut-away view of a portion of the process chamber shown in Figure 12A. [0047] Figure 13A is a top isometric view of a paddle assembly and associated housing and support arrangement.

[0048] Figure 13B is a bottom view of the assembly, housing and support arrangement shown in Figure 13A.

[0049] Figure 13C is a cross-sectional illustration of the assembly, housing and support arrangement, taken substantially along line 13C-13C of Figure 13A.

[0050] Figure 14 is a top isometric view of the process chamber shown in

Figure 12, illustrating a motor and linear guide coupled to an agitator.

[0051] Figure 15A is an exploded isometric illustration of the linear guide shown in Figure 14. [0052] Figure 15B is a cross-sectional illustration of the linear guide shown in

Figure 14.

[0053] Figure 15C is a cross-sectional illustration of the linear guide, taken substantially along line 15C-15C of Figure 15B.

[0054] Figure 16 is an enlarged isometric view of a robot transfer device for use in a processing system, such as the system 600 shown in Fig. 11. [0055] Figure 17 is a flow diagram illustrating a process for detecting and correcting or updating the rotational orientation of a workpiece.

[0056] Figure 18 is an isometric illustration of a transfer device moving a wafer or workpiece to a support for rotational re-orientation.

[0057] Figure 19 is an isometric illustration of a transfer device positioned to correct or update the rotational orientation of a workpiece by its location when the workpiece is transferred to a support.

[0058] Figure 20 is a partially exploded illustration of a system structure including decks to support tool components.

[0059] Figure 21 is a partially cut-away, top isometric view of the structure shown in Figure 20.

[0060] Figure 22 is a partial top view of an alternative paddle array.

[0061] Figure 23 is a section view taken along line 23-23 of Figure 22.

[0062] Figure 24 is an enlarged section view of one of the paddle elements shown in Figures 22 and 23.

DETAILED DESCRIPTION

ELECTRODES AND COMPENSATION OF WAFER MISALIGNMENT [0063] Wafers or workpieces can be semiconductor pieces (e.g., silicon wafers, gallium arsenide wafers, etc.), non-conductive pieces (e.g., ceramic substrates, glass, etc.), conductive pieces (e.g., doped wafers, conductive substrates, etc.) or other substrates on and/or in which micro-devices are formed. Typical micro-devices include microelectronic circuits or components, thin-film recording heads, data storage and memory elements, micro-flu id ic, micro-optical, micro-mechanical, and micro-electromechanical devices Electrochemical processing here includes electroplating, electro-etching, electropolishing, and/or anodization.

[0064] Figure 1 is a side view of an apparatus 100 for electrochemically processing a wafer W. The apparatus 100 includes a vessel 110 having a processing zone Z in which a surface S of the wafer W can be positioned for electrochemical processing. The vessel 110 is configured to contain a flow of processing fluid, and at least one counter electrode (not shown in Figure 1 ) is positioned in the vessel 110. The wafer W can be electrically connected to a power supply such that the wafer W is a working electrode that acts as either an anode or cathode, and the counter electrode in the vessel acts as the other of the cathode or anode. The apparatus 100 further includes a supplementary electrode 120 that is configured to operate independently from the counter electrode in the vessel, and a supplementary virtual electrode 130 in, or at least proximate to, the processing zone Z. The supplementary electrode 120 can be a thief electrode that acts through the supplementary virtual electrode 130 to control or otherwise influence the electric field at a perimeter portion of the wafer W. The supplementary electrode 120 and supplementary virtual electrode 130 are configured to compensate for misalignment between the wafer W and the counter electrode in the vessel 110 as explained in more detail below.

[0065] The supplementary electrode 120 is an actual or real physical electrode. The supplementary virtual electrode 130 is the space or area at which the supplementary electrode 120 causes an electrical field effect. Hence, the supplementary virtual electrode 130 is shown in dotted lines in Fig. 1 , because it is a virtual element, rather than a real or physical element.

[0066] Figure 2 is an isometric view of a portion of the apparatus 100 that shows several features in greater detail. Referring to Figures 1 and 2 together, the apparatus 100 can further include a wafer holder 140 having a support 142 configured to hold the wafer W in the processing zone Z. The support 142, more specifically, is configured to hold the surface S of the wafer W face down in a horizontal orientation in contact with a processing fluid flowing upwardly through the processing zone Z. The wafer holder 140 also has at least one electrical contact 144 configured to provide an electrical current to the wafer W. The wafer holder 140, for example, can have a contact configured to contact the backside of the wafer W. The wafer holder 140 can alternatively include a plurality of electrical contacts 144 configured to engage a perimeter portion of the surface S of the wafer W either in lieu of or in addition to a backside contact. The wafer holder 140 may also include a seal at the lower lip of the support configured to seal against a perimeter portion of the surface S of the workpiece W.

[0067] As also shown in Figures 1 and 2, the vessel 110 can further include a member 112 with an inner edge 114, a rim 116 above the inner edge 114, and a perimeter 118. In the example of the apparatus 100 shown in Figure 2, the inner edge 114 of the member 112 is positioned in a plane corresponding to a portion of the support 142 such that the supplementary virtual electrode 130 has an aperture defined by the space between the inner edge 114 and the support 142. The aperture of the virtual supplementary electrode 130 can be in a plane that is at least generally parallel to a processing plane of the wafer W and located at a lower portion of the wafer holder 140. The shape of the aperture of the supplementary virtual electrode 130 is accordingly a function of the space between the support 142 and the inner edge 114 such that the aperture will be narrower on one side of the wafer holder 140 and wider on an opposing side when the wafer holder 140 and the vessel 110 are misaligned with each other relative to an axis A-A (Figure 1 ). The aperture of the supplementary virtual electrode 130, for example, can have a first width at one side of the wafer holder 140 and a second width different than the first width at another side of the wafer holder 140 corresponding to the degree of misalignment between the wafer holder 140 and the vessel 110. Therefore, as explained in more detail below, the supplementary virtual electrode 130 self- compensates for any misalignment between the wafer holder 140 and the vessel 110 to counteract a corresponding offset between the wafer W and a counter electrode in the vessel 110.

[0068] The apparatus 100 can further include a mount 150 above the member 112. Referring to Figure 2, the mount 150 and the member 112 form a compartment 151 having a first flow outlet 152 through which a portion of the processing fluid can exit the processing zone and flow over the perimeter 118 of the vessel 110. The compartment 151 is also configured to contain the supplementary electrode 120 at a location above the processing zone Z. In the example illustrated in Figure 2, the supplementary electrode 120 is located above the member 112 at a radial position between the inner edge 114 and the perimeter 118. The supplementary electrode 120 can be attached to the mount 150 by a number of posts or tabs 122 to suspend the supplementary electrode 120 in the compartment 151 between the mount 150 and the member 112. In an alternative embodiment, the supplementary electrode can be embedded within a recess 123 (shown in broken lines) in the underside of the mount 150. It is generally preferable to have the supplementary electrode 120 suspended in the compartment 151 to avoid chemicals from collecting in such a recess, and also to provide additional surface area for the supplementary electrode 120 to contact the processing fluid. The supplementary electrode 120 can be coupled to a power supply via a connector 126.

[0069] The mount 150 further includes a brim 154 and a plurality of optional channels 156 (shown in broken lines) through which the processing fluid can flow between the mount 150 and the wafer holder 140. The channels 156 accordingly provide a second flow outlet for the processing fluid. The flow of processing fluid through the channels 156 wets the brim 154 and the upwardly facing inclined surface of the mount 150 to avoid crystal formation on the top of the mount 150 that can occur when the processing fluid dries. As explained in more detail below, this feature enables the wafer holder 140 to bottom out against the brim 154 without contacting crystal formations on top of the mount 150 to avoid skewing the wafer holder at an improper angle.

[0070] Figures 3 and 4 are cross-sectional views illustrating the operation and advantages of the apparatus 100. Figure 3, more specifically, illustrates the apparatus 100 during a state without a wafer in position for processing. The processing fluid F flows upwardly U through an opening defined by the member 112. The upper level of the processing fluid F is defined by the brim 154 of the mount 150; the brim 154 accordingly acts as a weir, and the fluid height of the processing fluid F is generally slightly above the height of the brim 154. The processing fluid F flows over the top of the brim 154 and the upwardly facing inclined surface of the mount 150 between processing cycles to avoid crystal formations on the top of the mount 150. This feature mitigates misalignment of the wafer holder during processing that can be caused by crystal formations on top of the brim 154. A portion of the processing fluid F also flows through the compartment 151 and through the outlet 152. This portion of processing fluid F flows outwardly past the perimeter 118 of the vessel 110 to carry away particles that are dislodged from the supplementary electrode 120. The processing fluid F is then filtered to remove particles, bubbles and other contaminants before it is recycled through the vessel 110.

[0071] Figure 4 illustrates the apparatus 100 during a processing cycle after the wafer holder 140 has positioned the wafer W in processing plane in the processing zone Z. The supplementary electrode 120 is activated during the processing cycle to provide an electric field component that acts through the supplementary virtual electrode 130 for controlling the current density in the perimeter region of the wafer W. In the example shown in Figure 4, the central axis of the wafer holder 140 is misaligned relative to the vessel 110 such that one side of the wafer holder 140 is closer to the member 112 than the opposing side. When this occurs, the width of the supplementary virtual electrode 130 is narrower on the side at which the wafer holder 140 is closer to the supplementary electrode 120 (side A), and wider on the side where the wafer holder 140 is further from the supplementary electrode 120 (side B). The narrow portion of the supplementary virtual electrode 130 restricts the electric field component of the supplementary electrode 120 in that region of the wafer holder 140 to reduce the influence of the supplementary electrode 120 in a corresponding region of the wafer W. Conversely, the wide portion of the supplementary virtual electrode 130 increases the electric field component of the supplementary electrode 120 in the region where the wafer W is further away from the supplementary electrode 120. The supplementary virtual electrode 130, therefore, self-compensates for misalignment between the wafer holder 140 and the vessel 110 because the shape of the aperture that defines the supplementary virtual electrode 130 is defined, at least in part, by the relative position between the wafer holder 140 and the corresponding structure of the vessel 110. The apparatus 100 accordingly provides a robust system that is less sensitive to misalignment between the wafer holder 140 and the vessel 110.

[0072] Another feature of the apparatus 100 is that the supplementary electrode 120 can be located very close to the supplementary virtual electrode 130, and the supplementary virtual electrode 130 is located close to the perimeter of the wafer W. The supplementary electrode 120 is located above the member 112 and proximate to the wafer holder 140 so that the distance to the supplementary virtual electrode 130 is short compared to the location of thief electrodes in prior art devices. This arrangement causes only a small voltage drop between the supplementary electrode 120 and the supplementary virtual electrode 130. The electrical resistance between the supplementary electrode 120 and the supplementary virtual electrode 130 is accordingly a function of the distance between these components, and the cross section area of the electrolyte between them. As a result, local resistance changes caused by a misalignment between the wafer holder 140 and the vessel 110 can constitute a significant percentage of the resistance value between a wafer W that is perfectly aligned with the supplementary electrode 120. The different widths of the different regions of the supplementary virtual electrode 130, therefore, will have a significant influence on the electric field at the perimeter of the wafer W to counteract non-uniformities caused by the misalignment. [0073] The supplementary virtual electrode 130 is close to the perimeter of the wafer W, to further enhance the ability of the system to counteract even small misalignments between the wafer holder 140 and the vessel 110. This dimension VE in Figure 4 is typically 6-14, 8-12, or 9-11 mm for a processor handling 200mm wafers. The cross-hatched space TP in Figure 4 indicates the compensating resistive path to the thief electrode 120. The path TP is short and wide, so that it has a low resistance. As a result, even small misalignments of the wafer with the anode result in sufficient compensating changes in the current flow near the edges of the wafer. Typically, the ratio of length or height of the path TP (from the arrow 130 to the electrode 120 in Fig. 2) to the width of the path WT ranges from about 0.5 to 2.5 or 0.8 to 1.6.

[0074] The apparatus 100 is particularly useful for plating materials onto wafers that are not rotated during the plating cycle. For example, magnetic media are fabricated by holding the wafer W stationary during a plating cycle to maintain the desired orientation between the magnetic field and the wafer W. In these applications any misalignment between the wafer holder and the vessel will cause a corresponding offset in the electric field relative to the surface S of the wafer W. The apparatus 100 with the supplementary electrode 120 and the supplementary virtual electrode 130 counteracts the non-uniformities caused by a misalignment between the wafer holder 140 and the vessel 110 to enable the supplementary electrode 120 to be spaced apart from the wafer holder and operate as a thief electrode in such applications.

[0075] Another advantage of the apparatus 100 is that it reduces the problems associated with particle contamination and makes it easier to maintain the supplementary electrode 120. More specifically, because the supplementary electrode 120 is spaced apart from the wafer W and resides in the exit flow of the processing fluid F, particles dislodged from the supplementary electrode 120 are carried away from the wafer W and out of the vessel 110. Such particles can then be filtered out of the processing fluid F before it is recycled to the vessel 110. Moreover, because the supplementary electrode 120 is positioned above the vessel 110, it is easily removed for maintenance by detaching the mount 150 from the vessel 110 without having to drain the vessel below the member 112 and/or disassemble the vessel 110. This feature will greatly enhance the ability to clean the supplementary electrode 120 without incurring significant downtime. As such, the apparatus 100 is also particularly applicable and advantageous in applications in which the supplementary electrode 120 is a thief electrode that is subject to frequent cleaning.

[0076] The apparatus 100 is also advantageous because it enhances the ability to control the current density at the perimeter of the wafer without changing the geometry of the chamber. As explained above, many existing plating chambers without thief electrodes use mechanical shields in the vessel to limit the current density at the edge of the wafer. Although these systems are useful, it is cumbersome to change such shields to adapt a chamber to process a different type of wafer. Moreover, such shields may limit the ability to provide the desired current to the perimeter of the wafer W at certain times of the plating cycle. The apparatus 100 improves the control of the current density at the perimeter of the wafer W because the supplementary virtual electrode 130 is located in, or at least proximate to, the processing zone Z. For example, when the supplementary virtual electrode 130 is located above any shields in the reactor and/or a virtual anode(s) in the vessel, the supplementary virtual electrode 130 has a strong influence on the current density at the perimeter of the wafer W. This configuration prevents the geometry of the vessel 110 from limiting the electric field component of the supplementary electrode 120. The current density in the perimeter of the wafer W, therefore, can be more fully controlled during a plating cycle by changing the current through the supplementary electrode 120 to compensate for electrical properties at the surface of the wafer W and in the processing fluid without being limited by the geometry of the vessel. As a result, the apparatus 100 can be adapted for plating different types of wafers and/or control of the current density during plating cycles by merely controlling the current through the supplementary electrode 120 without having to change the physical geometry of the chamber. This feature will greatly enhance the efficacy of plating onto thin seed layers or directly onto barrier layers where it is necessary to overcome the significant drop in current density across the wafer during the initial stages of the plating cycle. This feature is similarly important to applications with a high density of features for analogous reasons.

[0077] Figure 5 is a side view of an apparatus 200 in accordance with another design in which some features are shown in cross section and other features are shown schematically. The apparatus 200 includes a counter electrode 170 in the vessel 110 and a power supply 180 operatively coupled to the contacts 144 and the counter electrode 170. In this embodiment, the counter electrode 170 is a single electrode in the vessel 110. The vessel can contain a single processing fluid that flows upwardly to the wafer W, or the apparatus 500 can further include an ion exchange membrane 190 in the vessel 110, a first cell 192 on one side of the ion- membrane 190 for an anolyte or a catholyte, and a second cell 194 on the other side of the ion-exchange membrane 190 for the other of the catholyte or the anolyte. The apparatus 200 is accordingly an electroplating or electropolishing system that can operate in the same manner as the apparatus 100 described above with reference to Figures 1 -4.

[0078] Figure 6 is a side view of an apparatus 210 in accordance with still another design in which some features are shown in cross-section and other features are shown schematically. The apparatus 600 is similar to the apparatus 500 described above with reference to Figure 5, but the apparatus 600 includes a plurality of independently operable counter electrodes 170a-c that are electrically coupled to a plurality of independent power sources 182, 184 and 186, respectively. In operation, the counter electrodes 170a-c can establish an electric field within the apparatus 600 for plating material onto the wafer W or removing material from the wafer W. The apparatus 210 is accordingly an electroplating or electropolishing system that can operate in the same manner as the apparatus 100 and 200 described above with reference to Figures 1 -5.

[0079] The apparatus 210 is particularly useful for controlling the current density to compensate for variations in the bath conductivity, seed layer conductivity, and different thickness profile requirements for various wafers. During the initial part of a plating cycle for depositing copper onto a very thin seed layer or directly onto a barrier layer, the perimeter portion of the wafer has a much higher current density than the center portion because of the resistance of the seed layer or barrier layer. However, after enough copper has plated onto the wafer, the current density is much more uniform across the wafer. The apparatus 210 can compensate for such variations in the current density during the plating cycle by dynamically varying the current applied to each of the counter electrodes 170a-c and the supplementary electrode 120. In one specific embodiment of using the apparatus 210, the supplementary electrode 120 is a cathodic thief electrode, and the counter electrodes 170a-c are anodes that operate at different current levels. As material is plated onto the wafer, the current to the thief may be reduced and the current to each of the counter electrodes 170a-c may be varied to create the desired plating profile on the workpiece. Other aspects of using the apparatus 210 can include varying the currents to the counter electrodes 170a-c and the supplementary electrode 120 to compensate for changes in the bath conductivity over time as well as providing good control to plate different thickness profiles and different types of wafers.

[0080] Figure 7 is an example of an apparatus 300 wherein the virtual supplementary electrode 130 may be used. Figure 8 is a cross-sectional view of the apparatus 300 shown in Fig. 7. The apparatus 300 includes the supplementary electrode 120, supplementary virtual electrode 130, wafer holder 140, and mount 150. Generally, the width of the supplementary virtual electrode, shown as dimension WT in Fig. 2, is 8-20 or 10-15 times the expected wafer misalignment. For example, in the apparatus for a 200 mm diameter wafer as shown in Figure 7, if the maximum wafer misalignment is e.g., 1 mm, WT may be 10-15 mm. The apparatus 300 further includes a vessel 310 having a lower portion 312, an upper portion 314 with a horizontal processing zone Z where the wafer W is processed, and an interface 316 between the lower portion 312 and the upper portion 314. The interface 316 can be a gasket, filter and/or an ion-exchange membrane.

[0081] The apparatus 300 further includes one or more counter electrodes

330, such as the three that are shown and identified as first, second and third electrodes 330a, 330b and 330c, respectively. Accordingly, the lower portion 312 is also an electrode support having annular compartments 332 with upwardly extending walls that terminate near the interface 316. Each electrode 330a-c is positioned in a corresponding annular compartment 332. The upper portion 314 has channels 340 corresponding to the compartments 332, and each channel 340 has at least one upwardly extending dielectric wall to define virtual counter electrodes 350a-c corresponding to the electrodes 330a-c, respectively. The electrodes 330a- 330c, each of which can be independently controlled, can accordingly operate via the corresponding virtual counter electrodes 350a-c at locations below the supplementary virtual electrode 130.

[0082] In operation, the processing fluid enters the vessel 310 through a fluid inlet 318 that passes through a center opening in the lower portion 312 and an opening in the center of the innermost anode 330a. The processing fluid proceeds to a flow control assembly 320 that directs the processing fluid generally radially inward after which the fluid turns upwardly and flows toward the processing zone Z. A portion of the processing fluid flows through an opening defined by the inner edge 114 and over the rim 116 and the brim 154 as described above with respect to Figures 3 and 4. Another portion of the processing fluid flows downwardly through the channels 340, into the electrode compartments 332, and through an exit outlet in the lower portion 312.

[0083] The apparatus 300 can further include an agitator 360 between the virtual anodes 350a-c and the wafer holder 140. The agitator 360 includes a plurality of agitator elements 362 that can be elongated bars arranged generally parallel to each other. The agitator 360 reciprocates in a direction generally transverse to the longitudinal dimension of the agitator elements 362 to agitate the processing fluid in the processing zone Z. The apparatus 300 is particularly useful for applications that include an agitator and hold the wafer stationary during processing because the dielectric walls that define the virtual counter electrode 350a-c are located a sufficient distance below the wafer W to provide room for the agitator so that the agitator 360 does not greatly disturb the axis-symmetric electric field. Also, locating the virtual thief opening at the processing zone Z above the agitator 360 minimizes the disruption that the agitator may have on the thief electric field contribution. Therefore, the apparatus 300 having a virtual thief opening proximate to the workpiece holder 140 and above the agitator 360 in combination with a multiple anode system having virtual anodes located sufficiently below the wafer holder 140 to provide room for the agitator achieves superior control of the plating performance.

[0084] Another feature of the apparatus 300 is that the third virtual anode opening 350c has an outer diameter that is greater than the outer diameter of the seal against the perimeter of the wafer W. This feature allows the wafer holder 140 to be misaligned relative to the vessel 310 without having the perimeter of either side of the wafer W shielded by the outer diameter of the third virtual electrode 350c. As a result, the apparatus 300 minimizes the sensitivity to misalignment between the wafer holder 140 and the vessel 310 as well as radio manufacturing tolerances.

[0085] In an alternative embodiment, the vessel 310 can be configured to contain an anolyte separately from a catholyte. For example, the lower portion 312 can be a first cell and the upper portion 314 can be a second cell. The lower portion 312 can be one of an anolyte or catholyte cell through which a flow of a first processing fluid passes, and the upper portion 314 can be the other of a catholyte or anolyte cell through which a flow of a second processing fluid passes. The interface 316 in this type of reactor is an ion-exchange membrane that separates the first processing fluid in the lower portion 312 and from the second processing fluid in the upper portion 314. The ion-exchange membrane is configured to prevent the first and second fluids from passing between the lower portion 312 and the upper portion 314, but to allow the desired ion transfer across the membrane to carry out the electrochemical process.

[0086] In the design shown in Figure 9, the vessel 110 includes a member 402 that is similar to the member 112 described above with reference to Figures 1 -4.

The member 402 includes the inner edge 114 and the rim 116, but there is not an outlet at member 402. The apparatus also includes a mount 410 that is attached to, or integral with, the vessel 110 to form a compartment 420 in which the supplementary electrode 120 is positioned. The mount 410 has a brim that defines a single weir over which the processing fluid flows outwardly to the perimeter 418 of the vessel 110.

[0087] In the design shown in Figure 10, the vessel 110 includes the member

402, a mount 510 above the member that defines a compartment 512, and a supplementary electrode 520 having a first portion 522 in the compartment 512 and a second portion 524 outside of the compartment 512. The first portion 524 defines a flow channel such that the processing fluid flows along the supplementary electrode 520. More specifically, the processing fluid can flow outwardly along an underside of the first portion 522 and then inwardly relative to a central axis of the vessel 110 along an upper side of the first portion 522. The supplementary electrode 520 can be attached to the mount 510 using tabs in the compartment and/or the second portion 524 can be attached to the brim of the mount 510. The apparatus illustrated in Figure 10 eliminates the need to balance the flow between two exits as shown in the apparatus 100 illustrated in Figures 1 -4. The apparatus illustrated in Figure 10 may also provide satisfactory flow over the brim at a lower total overflow rate, and it may be less susceptible to ingesting bubbles as an agitator oscillates back and forth because it creates a longer path from the brim openings to the wafer W.

[0088] The member 112 may have different configurations, or the virtual supplementary electrode 130 may have a different location and/or orientation (e.g., inclined relative to the plane of the wafer or shaped by a different portion of the vessel). Additionally, the supplementary electrode 120 can be a de-plating electrode either in addition to or in lieu of being a thief electrode. Such de-plating electrodes can be used to de-plate material from the contacts of the wafer holder. In still additional embodiments, the supplementary electrode 120 can operate as another counter electrode. One example of this may be forward-reverse pulse plating. During the forward-current portion of the waveform, the supplementary electrode can function as a thief or cathode, while the counter electrodes in the vessel function as anodes. During the reverse-portion of the current waveform, the supplementary electrode can function as an anode whereas the counter electrodes in the vessel function as cathodes. In still other embodiments, the supplementary electrode can function as an anode while the counter electrodes in the vessel also function as additional anodes. In still additional embodiments, the shape of the inner edge and/or the shape of the outer surface of the wafer holder can be configured to shape the virtual supplementary electrode. The inner edge of the vessel and/or the outer edge of the wafer holder can be changed dynamically during or between processing cycles, or the shape of these features can be changed by replacing circular components with different shapes (e.g., ovals, ellipses, eccentric shapes, etc.).

DETAILED DESCRIPTION: AGITATOR DESIGNS [0089] The term "agitator" refers to a device that accelerates, stirs and/or otherwise energizes flow adjacent to a workpiece.

[0090] In Figure 11 , the system 600 includes a housing or cabinet (removed for purposes of illustration) that encloses a deck 604. The deck 604 supports processing stations 610, and a transport system 605. The stations 610 can include rinse/dry chambers, cleaning capsules, etching capsules, electrochemical deposition chambers, annealing chambers, or other types of processing chambers. At least some individual processing stations 610 include a vessel, reactor, or chamber 630 and a workpiece support 620 (for example, a lift-rotate unit) that supports an individual wafer or workpiece W during processing at the chamber 630. The transport system 605 moves the workpieces W to and from the chambers 630. Accordingly, the transport system 605 includes a transfer device or robot 606 that moves along a linear guidepath 603 to transport individual workpieces W within the system tool 600. The system tool 600 further includes a workpiece load/unload unit 601 having a plurality of containers for holding the workpieces W as they enter and exit the system tool 600.

[0091] In operation, the transfer device 606 includes a first carrier 607 with which it carries the workpieces W from the load/unload unit 601 to the processing stations 610 according to a predetermined work flow schedule within the system tool 600. Typically, each workpiece W is initially aligned at a pre-aligner station 610a before it is moved sequentially to the other processing stations 610. At each processing station 610, the transfer device 606 transfers the workpiece W from the first carrier 607 to a second carrier 621 located at the support 620. The second carrier 621 then carries the workpiece W while the workpiece W is processed at the corresponding process chamber 630. A controller 602 receives inputs from an operator and, based on the inputs, automatically directs the operation of the transfer device 606, the processing stations 610, and the load/unload unit 601. The transfer device 620 can also communicate with the controller 602 (e.g., via a first wired or wireless communication link 621 a), and/or directly with the support 612 (e.g., via a second wired or wireless communication link 621 b). In this manner, information corresponding to the orientation of the workpieces W is communicated from the transfer device 620 to portions of the tool 100 that control or implement the reorientation of the workpieces W.

[0092] Figure 12A is a cut-away illustration of one of the process chambers

630 shown in Figure 11. The process chamber 630 generally includes a vessel 631 that contains an electrochemical processing fluid for processing a workpiece W, a cut-away portion of which is shown in dashed lines in Figure 12A). The vessel 631 has a lower portion 639a through which the processing fluid enters, and an upper portion 639b having a horizontal process location P at which the workpiece W is processed. The processing fluid enters the vessel 631 through a fluid inlet 634 at the lower portion 639a and proceeds generally upwardly toward the process location P through a flow control assembly 638. The fluid at the process location P is in fluid and electrical communication with one or more electrodes 633, three of which are located below the process location P and are identified as first, second and third electrodes 633a, 633b and 633c, respectively. Accordingly, the lower portion 639a functions as an electrode support. Each electrode 633a-633c is housed in an annular chamber 632 having upwardly extending walls that terminate near the process location P. The electrodes 633a-633c, each of which can be independently controlled, operate as anodes and act at corresponding "virtual anode" locations positioned at the open tops of each electrode chamber 632. A ring contact assembly 622 acts as a cathode and provides a return path for current passing from the electrodes 633a-633c, through the electrochemical fluid and through the workpiece W. Alternatively, the return path can be provided by a backside contact, which contacts the upwardly facing, back surface of the workpiece W. After processing, the workpiece W can be rinsed and spun dry, typically referred to as a spin/rinse/dry or SRD process. An SRD lip 637 captures fluid flung from the workpiece W during the SRD process.

[0093] The vessel 631 also includes an agitator 640 positioned just below the workpiece W at the process location P. The agitator 640 includes multiple, elongated and spaced-apart agitator elements 642 that reciprocate back and forth as a unit within an agitator housing 641 , as indicated by arrow R. The agitator housing 641 includes a first weir 635 over which the processing fluid flows in a radial direction after it passes upwardly through the vessel 631 and outwardly across the surface of the workpiece W. The agitator housing 641 defines a portion of an agitator chamber 629 in which the agitator 640 reciprocates, with a lower portion of the agitator chamber 629 formed at least in part by the tops 627 of the electrode chambers 632, and an upper portion of the chamber formed at least in part by the workpiece W. [0094] The chamber 630 also includes a magnet assembly 670, which in turn includes two magnets 676 positioned on opposite sides of the vessel 631. The magnets 671 provide a magnetic field within the vessel 631 that magnetically aligns material in the processing fluid, e.g., as the material is deposited onto the workpiece W. In other embodiments, the chamber 630 need not include the magnet assembly 670, while still including other features described herein.

[0095] The overall process chamber 630 further includes a fourth electrode

633d positioned close to the process location P. The fourth electrode 633d may be coupled to a potential at a polarity opposite that to which the first-third electrodes 633a-633c are coupled (e.g., a cathodic potential). Accordingly, the fourth electrode 633d may operate as a current thief, thereby attracting material that would otherwise be deposited at the periphery of the workpiece W. In this manner, the fourth electrode 633d can counteract the "terminal effect," which typically results when the workpiece (a) is carried by the ring contact assembly 622 and (b) has a relatively high-resistance conductive layer exposed to the processing fluid. The fourth electrode 633d is carried by a second weir 636 over which at least some of the processing fluid may flow. Further details of this arrangement are described below with reference to Figure 12B, and additional details of the agitator 640 are then described with reference to Figures 13A-15C.

[0096] Figure 12B is an enlarged isometric illustration of the upper portion

639b of the process chamber 630 shown in Figure 12A. The agitator housing 641 seals against the upper portion 639b with a seal 628 (e.g., an O-ring seal). As shown in Figure 12B, the ring contact assembly 622 includes a ring contact 623 (shown schematically in Figure 12B) having contact elements that make electrical contact with the downwardly facing periphery of the workpiece W carried at the process location P. Typically, the ring contact 623 is coupled to a cathodic potential, so that the workpiece W is cathodic, but the ring contact 623 may selectively be coupled to an anodic potential as well. The ring contact assembly 622 also includes a ring contact seal 624 that protects the interface between the ring contact 623 and the workpiece W. The ring contact assembly 622 is carried by the support 620 (Figure 11 ) and accordingly moves upwardly and downwardly relative to the vessel 631 to move the workpiece W to and from the process location P.

[0097] While at the process location P, the workpiece W is in contact with the electrochemical fluid proceeding upwardly through openings between neighboring agitator elements 642, radially outwardly through the vessel 631 , and then over the first weir 635 and the second weir 636. At the same time, the agitator 640 reciprocates back and forth so that the agitator elements 642 agitate the fluid near the workpiece W. Each agitator element 642 has a diamond shape, with two oppositely-facing tapered ends, in the illustrated embodiment. In other embodiments, the agitator elements 642 have other shapes (e.g., a tapered shape, with a generally sharp end facing toward the workpiece W and a generally blunt end facing the opposite direction).

[0098] Figures 22-24 show an example of this type of design. In Figures 22- 24, an agitator 680 has equally spaced apart elements 682. The bottom surface 684 of each element 682 (facing down, and away from the workpiece) is generally flat. The upper section of the element 682 has an angled top section 686, a first straight section 688, a second angled section 690, and a second straight section 692. The top section 686 may have a narrow (0.2 - 2mm) flat top surface 684. The flat bottom 684 is about 3-8 or 4-6 times wider than the first straight section 688.

[0099] Fluid passing over the first weir 635 contacts the fourth electrode 633d

(e.g., the thief electrode) to provide electrochemical communication between the fourth electrode 633d and the peripheral region of the workpiece W. The close proximity between the fourth electrode 633d and the peripheral region of the workpiece W may provide greater control over the effects of the fourth electrode 633d. Fluid passing over the second weir 636 keeps the second weir 636 wet and can thereby prevent the formation of crystals, which may interfere with the proper seating between the ring contact assembly 622 (in particular, the seal 624) and the vessel 631 (in particular, the upper surface of the second weir 636). Accordingly, the second weir 636 can include castellations or other arrangements of projections and gaps that promote this fluid flow.

[00100] Figure 13A is a top isometric view of the agitator housing 641 and the agitator 640 shown in Figures 12A and 12B. The agitator elements 642 are elongated along axis E and arranged generally parallel to each other. In a particular embodiment shown in Figure 13A, the agitator elements 642 are separated by fluid- transmissible openings, and in other embodiments, the agitator includes a base (e.g., a solid base), with the agitator elements 642 projecting upwardly from the base to form a plurality of movable compartments that are open to the workpiece above.

[00101] The agitator 640 reciprocates in a direction generally transverse to the elongation axis E, as is indicated by arrow R. The agitator 640 is supported toward one end by a first support 643, and toward the opposite end by a second support

644. The first support 643 is connected to a drive motor, and the second support 644 is connected to a linear guide structure, both of which are described in greater detail below with reference to Figures 14-15C. The first and second supports 643, 644 are enclosed at least in part in corresponding splash chambers 645, which are positioned to contain and dampen fluid splashing and/or sloshing that may result as a consequence of the reciprocating action of the agitator 640. Chamber covers 646 are carried by each of the supports 643, 644 and move with the supports 643, 644 relative to the corresponding splash chamber 645. Accordingly, the chamber covers 646 accommodate the motion of the agitator 640, and prevent or at least restrict fluid from splashing out of the splash chambers 645.

[00102] Figure 13B is a bottom isometric view of the agitator housing 641 and the agitator 640 shown in Figure 13A. In the illustrated arrangement, the agitator elements 642 are integrally formed with each other from a single piece of machined or cast stock that includes an encircling rim 647. An advantage of this arrangement is that it improves the rigidity of the agitator elements 642 and the agitator 640 overall, resulting in more consistent spacing between the agitator elements 642 and the workpiece adjacent to which they reciprocate. Couplings 648 at each end of the agitator 640 connect the agitator 640 to the first support 643 and the second support 644. The agitator housing 641 includes slots 649 that receive the agitator 640 and the couplings 648 and accommodate the reciprocal motion of the agitator 640 while also containing, at least in part, the fluid within the agitator housing 641. Accordingly, the slots 649 can be small enough to reduce significant splashing, which is further reduced by the presence of the splash chambers 645.

[00103] Figure 13C is a cross-sectional illustration of the agitator 640 and agitator housing 641 , taken substantially along line 13C-13C of Figure 13A. Figure 13C illustrates the agitator 640 positioned within the agitator housing 641 , along with the first support 643 connected toward one end of the agitator 640 with one coupling 648, and the second support 644 connected toward the opposing end of the agitator

640 with another coupling 648. The couplings 648 and/or the agitator 640 extend through the slots 649, which accommodate reciprocal motion of the agitator 640 generally transverse to the plane of Figure 13C. The splash chambers 645 extend around the first support 643 and the second support 644 to contain fluid that passes into the splash chamber 645 through the slots 649. The chamber covers 646 restrict or prevent fluid from splashing outside of the splash chambers 645.

[00104] Figure 14 is a top isometric illustration of the agitator 640 and the agitator housing 641 installed in a process chamber 630. With the agitator housing

641 installed, the first support 643 and the second support 644 extend upwardly above the process location P and out of the corresponding splash chambers 645. For purposes of illustration, the chamber covers 646 (Figure 13C) have been removed. The first support 643 is connected to a linear drive device 651 , which is driven by a motor 650. Drive bellows 652 are positioned around the linear drive device 651 to protect it from the chemical environment within and adjacent to the process chamber 630, while allowing the motor 650 to drive the agitator 640 back and forth, as indicated by arrow R. The second support 644 extends out of the opposing splash chamber 645, where it is connected to a linear guide 653. The linear guide 653 supports the agitator 640 as the agitator 640 reciprocates, thereby maintaining the agitator elements 642 at a consistent spacing from the process location P. At the same time, the linear guide 653 is not so restrictive as to cause binding when the motor 650 drives the agitator 640 back and forth. Further details of particular arrangements for the linear guide 653 are described below with reference to Figures 15A-15C.

[00105] Figure 15A is an exploded view of the linear guide 653 described above with reference to Figure 14. The linear guide 653 includes an elongated, generally U-shaped guide rail 654 carried at opposing ends by corresponding mounts 657. A guide carriage 655 slides or rolls along the guide rail 654 and is attached to the second support 644 (Figure 14) with a bracket 661. Guide bellows 656 are positioned on either side of the guide carriage 655 to protect the guide rail 654 and internal components from the local environment.

[00106] Figure 15B is a cross-sectional illustration of the linear guide 653 described above with reference to Figure 15A, after assembly. In the illustrated arrangement, the guide carriage 655 includes multiple rollers 658 that engage with and roll along the guide rail 654. In a particular arrangement, the rollers 658 include three rollers, illustrated as two first rollers 658a and a second roller 658b. In a particular aspect of this arrangement, the first rollers 658a have a fixed relationship relative to the guide rail 654 in a direction transverse to the plane of Figure 15B, while the second roller 658b can be adjusted in the transverse direction to have a desired location relative to the guide rail 654 that reduces the tendency for the guide carriage 655 to bind with the guide rail 654. Further details of this arrangement are described below with reference to Figure 15C.

[00107] Figure 15C is a cross-sectional illustration of the linear guide 653, taken substantially along line 15C-15C of Figure 15B. Although the section is taken through the second roller 658b, the following discussion describes aspects of both the first rollers 658a and the second roller 658b. Linear guide mechanisms having the following characteristics are available from the Rollon Corporation of Sparta, New Jersey, USA.

[00108] In Figure 15C, the guide rail 654 includes an inner side wall 659a, an opposing outer side wall 659b, an inner lip 660a positioned above the inner side wall 659a, and an outer lip 660b positioned above the outer side wall 659b. The illustrated roller 658 can make contact with any of these surfaces as it rolls along the guide rail 654 in a direction into and out of the plane of Figure 15C.

[00109] When the roller 658 shown in Figure 15C is one of the first rollers 658a shown in Figure 15B, its lateral position relative to the guide rail 654 is fixed. When the roller 658 corresponds to the second roller 658b, its lateral position can be adjusted using an eccentric adjustment mechanism to move it laterally, as indicated by arrow L, relative to the guide rail 654. Accordingly, if the first rollers 658a are in contact with the inner side wall 659a, the second roller 658b can be adjusted so as to be spaced apart from both the inner side wall 659a and the outer side wall 659b. Otherwise, if the first rollers 658a are in contact with the inner side wall 659a, and the second roller 658b is in contact with the outer side wall 659b, the carriage 655 may bind in the guide rail 654. By adjusting the second roller 658b to allow at least some relative motion in the lateral direction L, the likelihood that the carriage 655 will bind is eliminated or at least reduced. At the same time, the arrangement of the rollers 658 and the guide rail 654 is such that a small amount of motion in the lateral direction L does not create a significant amount of motion in the vertical direction V. In this way, the vertical orientation of the agitator (which is carried by the guide carriage 655) remains fixed or at least approximately fixed so that the agitator does not shift upwardly and downwardly relative to the workpiece adjacent to which it reciprocates.

[00110] One way the vertical motion of the carriage 655 is restricted is by virtue of the inner lip 660a and the outer lip 660b. The two lips 660a-660b are sloped so that if the roller 658 shifts (e.g., from right to left in Figure 15C), the outer lip 660b tends to drive the roller 658 back downwardly by virtue of its sloped orientation. If the roller 658 then moves back to the right, the inner lip 660a performs the same operation. This arrangement reduces the amount of motion in the vertical direction

V while allowing at least some motion in the lateral direction L, thus reducing the tendency for the guide carriage 655 to bind.

[00111] The linear guide 653 may be positioned to restrict the movement of the agitator 640 toward and away from the process location along a first axis (e.g., as indicated by arrow V in Figure 15C). At the same time, the linear guide 653 allows linear translation of the agitator 640 along the reciprocation axis R, which is generally perpendicular to the vertical axis V. The linear guide 653 also allows for at least some movement of the agitator 640 along a third orthogonal axis perpendicular to the vertical axis V and the reciprocation axis R, as indicated by arrow L in Figure 15C, to at least reduce the tendency for the agitator 640 to bind with the linear guide 655. This arrangement produces a more reliable reciprocation operation, while preventing or at least restricting variations in the distance between the agitator 640 and the workpiece W across the surface of the workpiece W. This in turn is expected to produce more consistent agitation over the surface of the workpiece W, which is expected to produce more consistent process results (e.g., more consistent deposition results) across the surface of the workpiece W. [00112] The agitator 640 may be actively driven at one end by the motor 650 and linear drive device 651 , and supported (but not driven) at its opposite end by the linear guide 653. Put another way, the driving force that reciprocates the agitator 640 is directed through only one end of the agitator and only one end of the agitator elements 642. However, the agitator 640 is not cantilevered. Because the agitator 640 is not cantilevered, the agitator elements 642 are expected to have a more uniform separation from the workpiece W all across the workpiece W, thereby increasing the uniformity of the agitation produced at the process location P. In addition, as discussed above, the linear guide 653 is constructed to inhibit motion of the agitator 640 toward and away from the process location P, while allowing at least enough motion along the transverse axis L to prevent the agitator 640 from binding.

[00113] The agitator 640 may optionally be used a process chamber 630 that includes a thief or other electrode 633d that may perform a thieving function. The electrode 633d is positioned close to and above the edge of the workpiece W when the workpiece W is at the process location P. The location of the electrode 633d above the process location P and outside the weir 635 is expected to reduce the likelihood for particulates to enter and contaminate the agitator chamber 629. Furthermore, the radial direction of the flow through and out of the process chamber 629 is further expected to carry particulates away from the agitator chamber 629 rather than into the agitator chamber 629. Accordingly, while the local flow adjacent to the workpiece W changes direction as a result of the agitator 640 reciprocating within the agitator chamber 629, the bulk flow is radially outwardly over the weir 635.

[00114] The linear guide may have arrangements other than the particular roller arrangement described above, while still inhibiting motion of the agitator toward and away from the process location and at the same time allowing reciprocal motion of the agitator and preventing the agitator from binding.

DETAILED DESCRIPTION: WAFER ORIENTATION

[00115] Figure 16 illustrates a representative transfer device 605 shown in Figure 11. The transfer device 605 has a base 606 that moves along the guidepath 603 in Figure 11 and supports the first carrier 607. The first carrier 607 includes one or more articulatable links 724. The links 724 may include an arm 726 supported on a column 725 for rotation about an arm rotation axis 727, and one or more end- effectors 728 (two are shown in Figure 16) that are rotatable relative to the arm 726 about an end-effector rotation axis 729. The end-effector rotation axis 729 is offset from the arm rotation axis 727, and eccentric relative to the center of the workpiece W. In the illustrated design, each end-effector 728 is configured to carry a single workpiece W. Each end-effector 728 includes multiple ghppers 130 that grip the edges of a workpiece W at a corresponding gripping region 731.

[00116] In the arrangement shown in Figure 16, each end-effector 728 includes three ghppers 730, two of which are visible in Figure 16 and one of which is hidden by the position sensor 732. Accordingly, the workpieces W remain gripped by their edges while being carried by the transfer device 605. The workpieces W can be moved to a wide variety of positions and orientations via rotation of the arm 726 and/or the end-effectors 728. In a particular arrangement, one of the three ghppers 730 is fixed (e.g., the one hidden by the position sensor 732) and the other two (e.g., those visible in Figure 16) move toward and away from the fixed gripper 730. [00117] The transfer device 605 includes a position sensor 732, located to identify a rotational orientation of the workpiece W. The position sensor 732 is mounted on the arm 726, but the position sensor can also be on other parts of the transfer device 720, or other parts of the system (e.g., the deck). The position sensor 732 includes a slot into which the workpiece W is inserted via rotation of the end-effector 728 about the end-effector rotation axis 729. With the workpiece W in the slot, a detector (e.g., an IR detector, laser-based detector, or other detector) housed in the sensor 732 is used to identify a rotational orientation of the workpiece W by detecting a particular feature of the workpiece W. The detected feature may be the flat or notch in the edge of the wafer, or a feature can having other characteristics. Suitable sensors 732 include an LX2-V series micrometer, available from Keyence Corporation of Osaka, Japan.

[00118] Figure 17 is a flow chart outlining a process 700 for determining the rotational orientation of a workpiece (e.g., via the position sensor 732 shown in Figure 16) and, if necessary, updating or correcting the rotational orientation. Process portion 701 includes retrieving a workpiece from an load/unload area with a transfer device, for example, retrieving a workpiece from the load/unload unit 601 with the transfer device 605 shown in Figure 11. In process portion 702, the workpiece is pre-aligned at a pre-aligner station. The pre-aligner station can carry the workpiece by its edges or centrally via a vacuum chuck or vacuum paddle. In process portion 703, the workpiece is transferred from the pre-aligner station and processed at one or more process chambers. As described above, the processes conducted at the process chambers may include a pre-wet process, a plating process, a spin/rinse/dry sequence, and/or others. [00119] The workpiece may be repeatedly gripped and released as it is moved back and forth between process chambers and the transfer device. As a result, the rotational orientation of the workpiece initially established in process 702 may change. Accordingly, process portion 704 includes identifying a rotational orientation of the workpiece while it is carried by the transfer device, for example, while the workpiece is on its way to a target process chamber at which an orientation-sensitive process is to be performed. In process portion 705, it is determined whether the rotational orientation is within acceptable limits. If so, the workpiece is placed on a workpiece support (process portion 706) and an additional process (e.g., an orientation-sensitive process) is performed on the workpiece while it is carried by the support at its proper rotational orientation (process portion 713). Accordingly, the workpiece is not rotated during some or all of this process. The orientation-sensitive process includes depositing magnetic materials in a representative process flow, but can include other processes in other cases.

[00120] If, in process portion 705, it is determined that the rotational orientation of the workpiece is not within acceptable limits, then the method proceeds to process portion 707, which includes rotationally re-orienting the workpiece without using a pre-aligner station. In process portion 708, the correction required to reorient the workpiece is established, for example, by comparing the sensed or measured orientation with a target orientation. This comparison can be performed by any suitable computer, controller or other device, e.g., by the controller 602 shown in Figure 11 , or by a device carried on-board the transfer device. The device performing the comparison may include appropriate instructions resident on an appropriate software, hardware, or other computer-readable medium. The instructions for carrying out the comparison and/or other associated tasks are generally programmable instructions, but may be "hardwired" or otherwise made permanent or semi-permanent in particular applications. These functions may be performed by a single device, or by multiple, distributed devices that are networked or otherwise linked in communication with each other.

[00121] After process portion 708, the workpiece can be re-oriented using any one (or more) of several different methodologies. One methodology includes placing the workpiece on a support (process portion 709) that is adjacent to the target process chamber. In process portion 710, the support is rotated to correct the rotational orientation of the workpiece. The workpiece is then processed while at the proper rotation and while being carried by the support (process portion 713). The support can include a lift-rotate unit 620, as shown in Figure 11 , or another suitable device.

[00122] Another re-orientation process includes determining the location of the transfer device and the required articulation of its links that will result in the proper orientation of the workpiece as it is handed off to the support (process portion 711 ). These location parameters can be determined by any suitable computer or controller, including those described above. Once the location parameters are identified, the workpiece is placed on the support (process portion 712) and processed while being carried by the support (process portion 713).

[00123] A difference between the two processes described above is that the first process (identified by process portions 709 and 710) uses the support to rotate the workpiece to its correct orientation, while the second process (identified by process portions 711 and 712) uses the relative positions of the transfer device and the articulatable links to provide the correct orientation. Further details of each of these processes are described below with reference to Figures 18 and 19, respectively.

[00124] Figure 18 illustrates a representative process in which the workpiece W is re-oriented by the support 620. In this embodiment, the transfer device 605 moves to a predetermined position proximate to a target process chamber 630 and its associated support 620. The sensor 732 identifies the rotational orientation of the workpiece W, e.g., while the transfer device 605 is in transit to the support 620, and the workpiece W is then transferred to the support 620. If the rotational orientation of the workpiece W requires a correction, the correction information is determined by and/or transmitted to the controller 602 (Figure 11 ). The head 623 of the second carrier 621 includes a rotor for rotating the workpiece W. The controller 602 directs the second carrier 621 to rotate the rotor holding the workpiece about axis A by an amount sufficient to correct the rotational orientation of the workpiece W. The second carrier 621 is then inverted, so that the workpiece W rests on a ring contact assembly 740 and the workpiece W is processed at the target process chamber 630. As discussed above, the process conducted at the target process chamber 630 will typically require a specific rotational orientation of the workpiece W. For example, the process may include magnetically orienting conductive particles deposited on the surface of the workpiece W, using a magnetic field provided by one or more magnets. In this type of process, the rotor in the head 623 holding the workpiece is generally kept stationary.

[00125] Figure 19 illustrates the transfer device 005 in the process of adjusting the rotational orientation of the workpiece W as the workpiece is transferred to the second carrier 621. Accordingly, the second carrier 621 need not rotate to achieve the corrected orientation. Instead, the controller 602 (Figure 11 ) determines the necessary location of the transfer device 605 along the guidepath 603, and the necessary angular orientations of the arm 726 and the end-effector 728 that will result in the workpiece W arriving at the second carrier 621 in the proper rotational orientation. The controller 602 performs this calculation using the known geometric and kinematic relationships between the second carrier 621 , the transfer device 605, the arm 726, and the end-effector 728 to position these components properly. The proper position is obtained by translating the transfer device 605 along the guidepath 603 (as indicated by arrow T), rotating the arm 726 about the arm rotation axis 727 (as indicated by arrow R1 ), and/or rotating the end effector 728 about the end effector axis 729 (as indicated by arrow R2). Once the workpiece W is properly positioned at the second carrier 621 , the second carrier 621 inverts and lowers the workpiece W into the target process chamber 630 for processing.

[00126] The workpiece W need not necessarily be rotated by the second carrier 621 when the method described with reference to Figure 19 is used. In other methods, the orientation process performed by the transfer device 605 as shown in

Figure 19 can be supplemented by additionally rotating the workpiece W at the second carrier 621 , as discussed above with reference to Figure 18. This arrangement may be used if, for example, the required correction for the rotational orientation of the workpiece W is beyond the kinematic limits of the transfer device components.

[00127] One feature of the illustrated system described above with reference to Figures 16-19 is that the workpiece W is rotationally re-oriented without requiring the workpiece to first be delivered to and aligned at a separate pre-aligner station. Instead, a rotational misalignment of the workpiece is identified while the workpiece W is carried by the robot or transfer device 605, and the workpiece W is rotationally re-oriented by the transfer device 605 and/or the support 620 to which the workpiece W is delivered. An advantage of this arrangement is reducing the amount of time required to re-orient the workpiece W, as compared with a process that requires the workpiece W to be re-oriented at a separate pre-aligner station.

[00128] Another feature of the illustrated systems and methods described above is that the workpiece W is carried by the same end-effector 728, both when it is being transported between locations at the system 600, and when its rotational orientation is being assessed. An advantage of this arrangement is that the transfer device 605 need not be outfitted with a separate carrier or support (e.g., a vacuum chuck), just for the purpose of determining the rotational orientation of the workpiece W.

[00129] The end-effector 728 illustrated in the Figure 16 is an edge-grip end- effector, but other types may of course be used. For example, the end-effector 728 can have a vacuum paddle configuration in which it carriers the workpiece W at or toward its center, and holds the workpiece W by drawing a vacuum through one or more vacuum parts. Alternatively, the end-effector 728 can include multiple pegs, between and/or on which the workpiece W rests.

[00130] The end-effector 728 grips the workpiece W at its edges while the workpiece is transferred to the process chamber 630 and while the sensor 732 detects the rotational orientation of the workpiece W. An advantage of this arrangement, in addition to protecting the front and back surfaces of the workpiece

W, is that the workpiece W can be wet when its orientation is determined and when its orientation is changed. Conversely, a typical vacuum chuck-based pre-aligner requires that the workpiece be dry. By eliminating the requirement for a dry workpiece W, the time necessary to identify and change (if necessary) the rotational orientation of the workpiece W is reduced.

[00131] The design shown in Figures 16-19 is relatively simple to implement. For example, the sensor 732 can be installed on an existing type of transfer device 605, thereby adding the ability to detect the rotational orientation of the workpiece W without affecting many of the existing features of the transfer device 605. Furthermore, if the rotational orientation of the workpiece W is to be updated using the second carrier 621 and the support 620, these components are typically already equipped to rotate the workpiece W, and need only receive information identifying how far to rotate the workpiece W to achieve the proper orientation. If, on the other hand, the transfer device 605 and its articulatable links 724 are used to re-orient the workpiece W, the transfer device 605 typically already includes the articulatable links 724 and accordingly need only receive position information to properly orient the workpieces W.

[00132] The transfer device may have configurations other than those specifically shown in the Figures and described in the text, and may move along guidepaths other than linear guidepaths (e.g., rotary guidepaths). The end-effectors may have rollers (as is specifically shown in the Figures) or other gripping features, including vacuum ports carried by a paddle-type end-effector. The sequence of steps described above with reference to Figure 18 may in some cases be combined with the sequence of steps described above with reference to Figure 19. Process steps described above with reference to Figure 17 (e.g., process portions 702 and/or 703) may be eliminated or performed in a different order in alternate embodiments.

DETAILED DESCRIPTION: MAGNET DESIGNS

[00133] Figure 20 is a partially exploded, isometric view of a portion of an underlying structure 800 that may be used in the system 600 shown in Figure 11. The deck 604 of the system 600 includes a first portion 811 a having a first deck surface 813a, and a second portion 811 b having a second deck surface 813b. The deck portions 811 a, 811 b are positioned on opposite sides of a transfer device trough 812. The transfer device trough 812 supports the robot or transfer device 606 (Figure 11 ) for motion along the guide path 603 so that the transfer device 605 can access processing stations mounted on either the first deck surface 813a or the second deck surface 813b. The deck surfaces 813a, 813b may be at different elevations (e.g., with the second deck surface 813b higher than the first deck surface 813a). The transfer device 642 (Figure 11 ) is then designed to access processing stations at both elevations.

[00134] The first and second deck surfaces 813a, 813b include chamber mounts 827 for carrying processing chamber components, and support mounts 826 for carrying workpiece support components. Each deck surface 813a, 813b also includes a chamber opening 825 that accommodates a chamber 630 (Figure 11 ) or a portion of the chamber 630 that extends below the corresponding deck surface. The deck surfaces 813a, 813b and the trough 812 have registration features 816, including first registration features 816a, second registration features 816b, and third registration features 816c. The registration features 816 include precision mating elements (e.g., fixed alignment pins and corresponding holes) that provide for precise alignment between the components of the system 600. Accordingly, transfer device components engaged with the third registration features 816c (in the trough 812) will be in precise alignment with processing station components engaged with the first registration features 816a (at the first deck surface 813a), and with processing station components engaged with the second registration features 816b (at the second deck surface 813b). This arrangement reduces or eliminates misalignments between the transfer device 605 and the processing stations 630 (Figure 11 ).

[00135] The second portion 811 b of the deck 810 includes an enclosure 820 carried by a subdeck surface 814. Accordingly, the enclosure 820 includes fourth registration features 816d that engage with fifth registration features 816e carried by the subdeck surface 814. This arrangement preserves the precise alignment between transfer device components in the trough 812, and processing station components carried at the second deck surface 813b.

[00136] In addition to maintaining the registration between transfer device components and processing station components, the enclosure 820 protects components housed within it from the chemical environment present in the system 600. These components include relatively large, powerful (and therefore heavy) magnets described in further detail below with reference to Figure 21. In the design shown, the enclosure 820 includes a base 822, a top 821 (the external surface of which also corresponds to the second deck surface 813b), opposing end walls 823, and opposing side walls 824 (shown partially cut-away). The enclosure 820 is also defined by chamber opening walls 828 that surround the chamber opening 825. This box-type arrangement forms a structurally stiff enclosure 820, suitable for carrying heavy components, including the large magnets. In particular, the sidewalls

824, end walls 823, and/or chamber opening walls 828 provide a load path between the base 822 and the top 821 , allowing the top 821 to supplement the support provided by the base 822. Furthermore, the base 822, side walls 824, end walls 823, chamber opening walls 828, and top 821 are connected to each other to form a chemical-tight (or at least chemically resistant) boundary around the magnets. The components of the enclosure 820 may be welded together and coated with a gas- and/or liquid-tight sealant. Suitable sealants include powder-coat polymer paints. This arrangement protects components within the enclosure 820 from the chemical environment outside the enclosure 820. In particular, this arrangement protects the magnets, which are typically formed from magnetite or other materials that are otherwise very susceptible to corrosion, from chemicals outside the enclosure 820.

[00137] Figure 21 is a top isometric view of the deck arrangement shown in Figure 20, with the enclosure 820 mounted to the subdeck surface 814, and with a portion of the second deck surface 813b cut away to expose components within the enclosure 820. These components include a magnet assembly 850, that in turn includes a first magnet 851 a positioned on one side of the chamber opening 825, and a second magnet 851 b positioned on the opposite side of the chamber opening

825. Corresponding magnet supports 853a and 853b secure the first and second magnets 851 a, 851 b in position.

[00138] The magnetic flux lines between the two magnets 851 a, 851 b tend to bulge outwardly and/or stray from the region between the two magnets, in the absence of measures taken to direct the flux lines. This can produce adverse effects, including (a) a skewed magnetic field in any process chamber located between the magnets 851 a, 851 b, and/or (b) interference with motors and/or other electronic equipment carried by the tool. In at least some cases, the skewed magnetic field adversely affects the uniformity of the material deposited on a workpiece in the process chamber, and the interference adversely affects the rate and/or accuracy with which components in the tool operate. Aside from the magnets 851 a, 851 b and possibly the magnet supports 853a, 853b, most, if not all of the components making up the deck 810 are generally non-magnetic. For example, the deck surfaces 813a, 813b, the subdeck 814, and the enclosure 820 are typically formed from stainless steel (e.g., a 300-series stainless steel, such as 304 stainless steel) or another corrosion-resistant non-magnetic material, and are generally relatively thin. Accordingly, they have little or no effect on the magnetic flux lines between the magnets 851 a, 851 b.

[00139] In the design shown in Figure 21 , the magnet assembly 850 includes a first magnetic return path 852a positioned between the first and second magnets 851 a, 851 b on one side of the chamber opening 825, and a second magnetic return path 852b positioned on the opposite side of the chamber opening 825. The first and second magnetic return paths 852a, 852b align the magnetic flux lines between the first magnet 851 a and the second magnet 851 b to be generally parallel to the return paths 852a, 852b and generally transverse (e.g., perpendicular) to the first and second magnets 851 a, 851 b, as indicated by magnetic flux lines B. One advantage of this arrangement is that the magnetic flux lines B will have a known and generally consistent orientation across the chamber opening 125 and accordingly throughout a process chamber 831 installed in the chamber opening 825. As a result, more uniform electroplating may be achieved. [00140] The second magnetic return path 852b, in addition to aligning the magnetic flux lines as described above, acts as a shield between the magnets 851 a, 851 b and the trough 812. The shield can form part of an overall shielding arrangement that reduces the effects of the magnetic fields created by the magnets 851 a, 851 b on other components within the system 600.

[00141] The magnet assembly 850 can be arranged to provide for long component life spans, ease of manufacturability, and ease of maintenance. For example, the first magnetic return path 852a is housed in the enclosure 820. This component is typically formed from a ferromagnetic material and accordingly may be susceptible to corrosion without the protection of the enclosure 820. In some embodiments, the second magnetic return path 852b is also placed in the enclosure 820 to provide similar protection. In the design in Figure 21 , however, the second magnetic return path 852b is positioned exterior to the enclosure 820, and out of contact with the first and second magnets 851 a, 851 b. In this position, the second magnetic return path 852b can still direct the magnetic flux lines B in the desired manner, and can also enhance manufacturing and maintenance operations. For example, by not attaching the second magnetic return path 852b to the other components of the magnet assembly 850, the magnet assembly 850 has an open- ended shape, formed by the two magnets 851 a, 851 b, the magnet supports 853a, 853b, and the first magnetic return path 852a. This configuration can be easily installed into the enclosure 820 by sliding it toward the trough 812, without disturbing the second deck surface 813b. If necessary, this portion of the magnetic assembly 850 can be removed by sliding it away from the trough 812 and out of the enclosure 820. The second magnetic return path 852b can be separately protected from the chemical environment within the system 600 by coating it with an appropriate sealant/coating, as described above relative to an enclosure 820. If it becomes necessary to replace the second magnetic return path 852b, the replacement operation is completed without disturbing the enclosure 120.

[00142] Figure 18 illustrates the system 600 with a process chamber 630 positioned at one of the chamber mounts 827 so as to extend into a corresponding chamber opening. The support 620 is positioned at a corresponding support mount

826. The support 620 includes a second carrier 621 that carries a workpiece W into contact with processing liquid in the chamber 630. To protect these motors from the potentially interfering effects of the magnet assembly 150, the agitator drive motor 650 includes a magnetically conductive agitator motor shield 862, and the carrier drive motor 836 includes a magnetically conductive carrier motor shield 837.

[00143] The system 600 also includes a transfer device shield 861 positioned between the magnet assembly 850 and the trough 812. This shields the motors of the transfer device 606 from the effects of the magnet assembly 850. The shield 861 functions as both the transfer device shield 861 and the second magnetic return path 852b. This preserves the compact configuration of the system 600 (by combining multiple functions in a single structure), thus reducing the amount of clean-room floor space required for the system 600. The transfer device shield 861 and the second magnetic return path 852b may alternatively be separate structures.

[00144] The transfer device shield 861 which can double as the second magnetic return path 852b can be located inside the enclosure 820, rather than outside the enclosure as is shown in Figures 20 and 21. Or, the second magnetic return path 852b can be located within the enclosure 820, and the transfer device shield 861 can be located outside the enclosure 820. The enclosure 820 and/or other deck components may include plastics or other non-conductive, chemically resistant materials. The shields positioned around the support motor and/or the agitator motor can be located remote from the motors while still providing a shielding function. Shielding may be provided around components other than the motors identified above, for example, around a spin motor carried by the support to spin the workpiece during processing.

[00145] Each of the designs above may be used alone, or in combination with one or more other designs. For example, a system as shown in Figure 11 may have one or more electrochemical process chambers having the virtual supplemental electrode shown in Figures 1 -10, with, or without the process chambers having any of the paddle designs shown in Figures 12-15 or 22-24, and with or without the transfer device shown in Figures 16-19, or the magnet/shield designs shown in Figures 20-21.

Claims

1. An apparatus for electrochemically processing a wafer, comprising: a vessel having a processing zone in which a wafer is positioned for electrochemical processing; at least one counter electrode in the vessel; a supplementary electrode configured to operate independently from the counter electrode; and a supplementary virtual electrode in the processing zone, wherein the supplementary virtual electrode is configured to counteract an electric field offset relative to the wafer associated with an offset between the wafer and the counter electrode when the wafer is in the processing zone.

2. The apparatus of claim 1 wherein the supplementary electrode is located above the counter electrode.

3. The apparatus of claim 1 wherein the supplementary electrode is located above the processing zone.

4. The apparatus of claim 1 wherein the vessel includes a member having an inner edge, a rim above the inner edge, and a perimeter, and wherein the supplementary electrode is located above the member at a radial position between the inner edge and the perimeter.

5. The apparatus of claim 4 wherein the supplementary virtual electrode has an aperture for shaping an electric field component from the supplementary electrode, and wherein the aperture is formed, at least in part, by the inner edge of the member.

6. The apparatus of claim 1 wherein: the vessel includes a member having an inner edge, a rim above the inner edge, and a perimeter; the apparatus further includes a mount above the member, wherein the mount and the member form a compartment having a first flow outlet between the mount and the member through which a portion of the processing fluid can exit the processing zone and flow over the perimeter of the member, and wherein the mount includes a brim defining a second flow outlet for the processing fluid; and the supplementary electrode is in the compartment at a radial position between the inner edge and the perimeter.

7. The apparatus of claim 1 with the supplementary virtual electrode comprising an annular space in the processing zone.

8. The apparatus of claim 1 , further comprising a plurality of counter electrodes, and wherein the counter electrodes are configured to be operated independently from each other and the supplementary electrode.

9. The apparatus of claim 8, further comprising a plurality of virtual counter electrodes corresponding to the counter electrodes, wherein the virtual counter electrodes have apertures located below the virtual supplementary electrode.

10. The apparatus of claim 1 , further comprising a wafer holder having a wafer support configured to hold a wafer and an electrical contact, and wherein the virtual supplementary electrode has an aperture defined, at least in part, by the vessel and the wafer holder.

11. The apparatus of claim 1 wherein: the vessel includes a member having an inner edge, a rim above the inner edge, and a perimeter; and the apparatus further comprises a wafer holder having a wafer support configured to hold a wafer and an electrical contact configured to contact a plating surface of the wafer, and wherein the virtual supplementary electrode has an aperture defined, at least in part, by the inner edge of the member and the wafer support of the wafer holder.

12. The apparatus of claim 11 wherein the aperture of the supplementary virtual electrode has an outer diameter defined by the inner edge of the member and an inner diameter defined by an outer diameter of a portion of the wafer support.

13. The apparatus of claim 12 wherein the aperture of the supplementary virtual electrode has a first width at one side of the wafer holder and a second width different than the first width at an opposing side of the wafer holder.

14. The apparatus of claim 1 wherein the virtual supplementary electrode has an aperture with a first width at one side of the processing zone and a second width different than the first width at an opposing side of the processing zone when a central axis of the wafer is offset relative to a central axis of an electric field of the counter electrode.

15. An apparatus for electrochemically processing a wafer, comprising: a vessel having a processing zone through which a processing fluid can flow upward, a rim over which the processing fluid can flow out of the processing zone, and a perimeter radially outward from the rim over which the processing fluid can flow downwardly; a wafer holder having a support configured to hold a microfeature wafer in the processing zone and at least one electrical contact configured to provide an electrical current to the wafer; at least one counter electrode in the vessel; a supplementary electrode spaced apart from the wafer holder; and a virtual supplementary electrode having an aperture configured to shape an electric field component from the supplementary electrode, wherein the aperture is shaped, at least in part, by alignment between the wafer holder and the vessel to counteract non-uniformities associated with an offset between the wafer holder and the vessel when the wafer holder holds a wafer in the processing zone.

16. The apparatus of claim 15 wherein the aperture of the supplementary virtual electrode has an outer diameter defined by a portion of the vessel and an inner diameter defined by an outer diameter of a portion of the support of the wafer holder.

17. The apparatus of claim 16 wherein the aperture of the supplementary virtual electrode has a first width at one side of the wafer holder and a second width different than the first width at an opposing side of the wafer holder.

18. The apparatus of claim 15 wherein the virtual supplementary electrode has an aperture with a first width at one side of the processing zone and a second width different than the first width at an opposing side of the processing zone when a central axis of the wafer is offset relative to a central axis of an electric field of the counter electrode.

19. An apparatus for electrochemically processing a wafer, comprising: a vessel configured to direct a flow of processing fluid upward, wherein the vessel includes a processing zone through which the upward flow of processing fluid can pass; a wafer holder having a wafer support configured to hold a microfeature wafer at the processing zone in a position transverse to the upward flow of processing fluid and at least one electrical contact configured to contact a plating surface of the wafer; at least one counter electrode in the vessel; a stationary supplementary electrode; and a supplementary virtual electrode associated with the supplementary electrode, wherein the supplementary virtual electrode has an aperture with an outer edge define at least in part by the vessel and an inner edge defined at least in part by the wafer holder when the wafer holder holds a wafer in the processing zone.

20. The apparatus of claim 19, further comprising a plurality of counter electrodes, and wherein the counter electrodes are configured to be operated independently from each other and the supplementary electrode.

21. The apparatus of claim 20, further comprising a plurality of virtual counter electrodes corresponding to the counter electrodes, wherein the virtual counter electrodes have apertures located below the virtual supplementary electrode.

22. The apparatus of claim 21 wherein an outermost virtual counter electrode has an outer diameter greater than an outer diameter of the wafer.

23. The apparatus of claim 19, further comprising an agitator between the virtual counter electrodes and the wafer holder.

24. A method for electrochemically processing a wafer, comprising: positioning a wafer holder such that a wafer in the wafer holder is at a processing zone of the vessel; establishing an electric field in a processing fluid in the vessel using the wafer, a counter electrode in the vessel, and a supplementary electrode that is spaced apart from the wafer holder; and counteracting an offset of the electric field relative to the wafer associated with an offset between the wafer holder and the vessel when the wafer holder holds a wafer in the processing zone.

25. The method of claim 24 wherein the supplementary electrode affects the electric field via a supplementary virtual electrode in the processing zone, and wherein counteracting for the offset of the electric field relative to the wafer comprises shaping the supplementary virtual electrode to have a first width at a first side of the wafer holder and a second width different than the first width at a second side of the wafer holder.

26. The method of 24 wherein the supplementary electrode affects the electric field via a supplementary virtual electrode defined, at least in part, by a portion of the vessel at the processing zone and a portion of the wafer holder.

27. The method of claim 24, further comprising flowing the processing fluid upwardly through the processing zone and over a rim.

28. The method of claim 27 wherein the supplementary electrode affects the electric field via a supplementary virtual electrode in the processing zone, and wherein counteracting for the offset of the electric field relative to the wafer comprises shaping the supplementary virtual electrode to have a first width at a first side of the wafer holder and a second width different than the first width at a second side of the wafer holder.

29. The method of 27 wherein the supplementary electrode affects the electric field via a supplementary virtual electrode defined, at least in part, by a portion of the vessel at the processing zone and a portion of the wafer holder.

30. The method of 24 wherein the supplementary electrode is located above the counter electrode, and the method further comprises plating onto the supplementary electrode to thieve material relative to a perimeter of the wafer.

31. The method of claim 24 wherein the supplementary electrode is located above the processing zone, and the method further comprises plating onto the supplementary electrode to thieve material relative to a perimeter of the wafer.

32. The method of claim 24 wherein the supplementary electrode is located above the counter electrode, and the method further comprises de-plating material using the supplementary electrode.

33. The method of claim 24 wherein the vessel includes a member having an inner edge, a rim above the inner edge, and a perimeter, and wherein the supplementary electrode is located above the member at a radial position between the inner edge and the perimeter, and wherein the method further comprises plating onto the supplementary electrode to thieve material relative to a perimeter of the wafer.

34. The method of claim 33 wherein the supplementary virtual electrode has an aperture for shaping an electric field component from the supplementary electrode, and wherein the aperture is formed, at least in part, by the inner edge of the member, and wherein the method further comprises plating onto the supplementary electrode to thieve material relative to a perimeter of the wafer.

35. The method of claim 24 wherein: the vessel includes a member having an inner edge defining, a rim above the inner edge, and a perimeter; the apparatus further includes a mount above the member, wherein the mount and the member form a compartment having a first flow outlet between the mount and the member through which a portion of the processing fluid can exit the processing zone and flow over the perimeter of the member, and wherein the mount includes a brim defining a second flow outlet for the processing fluid; the supplementary electrode is in the compartment at a radial position between the inner edge and the perimeter; and the method further comprises plating onto the supplementary electrode to thieve material relative to a perimeter of the wafer.

36. The method of claim 35 wherein the supplementary virtual electrode has an aperture for shaping an electric field component from the supplementary electrode, and wherein the aperture is formed, at least in part, by the inner edge of the member, and wherein the method further comprises plating onto the supplementary electrode to thieve material relative to a perimeter of the wafer.

37. The method of claim 24, wherein the method further comprises establishing the electric field using a plurality of counter electrodes and operating the counter electrodes independently from each other and the supplementary electrode.

38. The method of claim 24 wherein counteracting the offset comprises configuring at least one of an inner edge of the vessel and an outer surface of the wafer holder to have a shape that defines a supplementary virtual electrode that compensates for the offset.

39. The method of claim 38, further comprising changing a shape of at least one of the inner edge of the vessel or the outer surface of the wafer holder.

40. The method of claim 38, further comprising replacing the inner edge or the wafer holder with a different inner edge or wafer holder.

41. A system for processing workpieces, comprising: a vessel configured to receive a processing fluid at a process location; a fluid inlet positioned to direct the processing fluid into the vessel; a weir positioned above the process location and outwardly from the fluid inlet to receive the processing fluid moving radially outwardly from the fluid inlet; a workpiece support positioned to carry a workpiece at the process location; an agitator having an elongated agitator element proximate to the process location; a first support carrying the agitator proximate to a first end of the agitator element, and a second support carrying the agitator proximate to a second end of the agitator element opposite the first end; a motor operatively coupled to the first support and not the second support to drive the agitator along a linear path relative to the process location; and a linear guide engaged with the second support.

42. The system of claim 41 wherein the agitator element is one of a plurality of elongated, spaced-apart agitator elements, with fluid-transmissible openings between neighboring agitator elements.

43. The system of claim 41 wherein the linear guide is positioned to (a) restrict movement of the agitator toward and away from the process location along a first axis, (b) allow linear translation of the agitator along the linear path aligned with a second axis generally perpendicular to the first axis, and (c) allow for movement of the agitator along a third axis generally perpendicular to the first and second axes to at least reduce the tendency for the agitator to bind with the linear guide.

44. The system of claim 43 wherein the linear guide includes a generally U-shaped channel having an upwardly facing opening, and wherein the channel carries rollers connected to the second support.

45. The system of claim 44 wherein at least one of the rollers is in contact with a first sidewall of the channel, and wherein none of the remaining rollers contacts a second sidewall facing toward the first sidewall.

46. The method of claim 45 wherein the channel includes lips extending inwardly toward each other from the upper ends of each of the sidewalls to restrict motion of the agitator toward and away from the process location.

47. The system of claim 44 wherein at least one of the rollers has a fixed position relative to the agitator and wherein another of the rollers has an adjustable position relative to the agitator.

48. The system of claim 41 , further comprising first and second magnets positioned on opposite sides of the vessel to orient material applied to a workpiece at the process location.

49. The system of claim 41 wherein the first and second supports extend upwardly away from the process location, and wherein the vessel includes first and second splash chambers, each extending upwardly from the process location and positioned around one of the first and second supports to contain fluid splashing.

50. The system of claim 41 , further comprising an electrode support positioned below the process location to carry multiple, independently controllable electrodes in fluid communication with the process location.

51. The system of claim 41 wherein the agitator element has a generally pointed upper extremity and a generally pointed lower extremity.

52. The system of claim 41 , further comprising an electrode positioned apart from the workpiece support and above the process location.

53. The system of claim 52 wherein the electrode is one of a plurality of electrodes, the one electrode being coupled to a potential at a first polarity, and wherein a subset of the electrodes are positioned in fluid communication with the process location and are coupled to a potential at a second polarity opposite the first, and wherein the workpiece support carries a contact coupled to a potential at the first polarity and positioned to contact a workpiece at the process location.

54. The system of claim 41 wherein the weir is a first weir, and wherein the system further comprises a second weir positioned radially outwardly from the first weir, the electrode being positioned between the first weir and the second weir.

55. A method for processing workpieces, comprising: directing processing fluid upwardly into a vessel toward a workpiece positioned at a process location of the vessel; directing the processing fluid radially outwardly adjacent to the workpiece and over a weir; and agitating the processing fluid adjacent to the workpiece with an agitator having an agitator element by: driving a first support positioned toward a first end of the agitator element; and guiding a second support along a linear guide path, without driving the second support, the second support being positioned toward a second end of the agitator element opposite the first end.

56. The method of claim 55 wherein guiding the second support includes: at least restricting movement of the agitator toward and away from the process location along a first axis; allowing linear translation of the agitator along the linear path in a direction aligned with a second axis generally perpendicular to the first axis; and allowing for movement of the agitator along a third axis generally perpendicular to the first and second axes to at least reduce the tendency for the second support to bind.

57. The method of claim 56 wherein allowing linear translation of the agitator along the linear path includes allowing a roller carried by the agitator to roll within a guide channel aligned along the linear path.

58. The method of claim 57 wherein the roller is a first roller that rolls along a first sidewall of a U-shaped channel having an upwardly facing opening, and wherein allowing for movement of the agitator along the third axis includes allowing a second roller carried by the agitator to be out of contact with the first sidewall and a second sidewall of the channel facing toward the first sidewall of the channel.

59. The method of claim 57 wherein the roller rolls along a first sidewall of a U-shaped channel having an upwardly facing opening and a lip extending at least partially across the opening, and wherein at least restricting movement of the agitator toward and away from the process location includes at least restricting motion of the roller via contact with the lip.

60. The method of claim 55 wherein agitating the processing fluid includes agitating the processing fluid with a plurality of elongated, spaced-apart agitator elements having fluid-transmissible openings between neighboring agitator elements.

61. The method of claim 55, further comprising containing processing fluid agitated by the agitator with a first splash chamber extending upwardly away from the process location around the first support, and with a second splash chamber extending upwardly from the process location around the second support.

62. The method of claim 55, further comprising orienting material applied to the workpiece via a magnetic field in the vessel formed between first and second magnets positioned on opposite sides of the vessel.

63. The method of claim 55, further comprising: depositing material on the workpiece from a plurality of anodes positioned in fluid communication with the workpiece; and attracting at least some of the material that would otherwise deposit on the workpiece to a cathode positioned apart from the workpiece and above the process location.

64. A transfer device for workpieces, comprising: a base unit movable along a guide path; a carrier movable relative to the base unit and having an end-effector positioned to engage a workpiece and move the workpiece toward and away from the base; and a position sensor located to identify a rotational orientation of the workpiece while the workpiece is carried by the end-effector.

65. The device of claim 64 wherein the end-effector is rotatable relative to the base about one or more axes eccentric to the workpiece.

66. The device of claim 64 wherein the carrier includes an arm carried by the base unit and movable relative to the base unit, and wherein the end-effector is carried by the arm and is rotatable relative to the arm.

67. The device of claim 64 wherein the end-effector includes first and second edge grippers positioned at a gripping region that receives a workpiece, the first edge gripper being movable toward and away from the second edge gripper between a grip position and a release position.

68. The device of claim 64, further comprising: a wireless communication device operatively coupled to the position sensor and movable with the position sensor along the guide path; and a controller operatively coupled to the position sensor via a wireless communication link provided by the wireless communication device to receive signals corresponding to the rotational orientation of the workpiece.

69. The device of claim 64, further comprising a controller operatively coupled to the sensor, the controller being programmed with instructions for: comparing the rotational orientation of the workpiece with a target value; determining a rotational orientation correction value; and directing a signal corresponding to the correction value.

70. The device of claim 64 wherein the base unit does not carry a device that supports the workpiece at its center and rotates the workpiece about its central axis.

71. A system for handling workpieces, comprising: a transfer device that is movable along a guide path, the transfer device having a first carrier positioned to releasably carry a workpiece; a processing chamber positioned along the guide path; a support positioned proximate to the processing chamber, the support having a second carrier positioned to carry a workpiece as it is processed at the processing chamber, the second carrier being rotatable relative to the processing chamber; a position sensor located to identify a rotational orientation of the workpiece; and a controller operatively coupled to the position sensor to receive a signal corresponding to the rotational orientation of the workpiece, the controller being operatively coupled to the support and programmed with instructions directing the second carrier to rotationally re-orient the workpiece based at least in part on the signal received from the position sensor.

72. The system of claim 71 wherein the position sensor is carried by the transfer device.

73. The system of claim 71 wherein the controller is programmed with instructions directing the second carrier to: rotationally re-orient the workpiece from a first rotational orientation to a second rotational orientation, based at least in part on the signal received from the position sensor; and maintain the workpiece in the second rotational orientation while the workpiece is processed at the process chamber.

74. The system of claim 71 wherein the transfer device includes: a base unit movable along the guide path; and an arm carried by the base unit and movable relative to the base unit to rotate a workpiece about an axis eccentric to the workpiece.

75. The device of claim 71 wherein the first carrier includes: an arm carried by the base unit and movable relative to the base unit; and an end-effector carried by the arm and rotatable relative to the arm.

76. The device of claim 75 wherein the end-effector includes first and second edge grippers positioned at a gripping region that receives a workpiece, the first edge gripper being movable toward and away from the second edge gripper between a grip position and a release position.

77. The system of claim 71 wherein the first carrier includes multiple end- effectors, with individual end-effectors having first and second edge ghppers positioned at an individual gripping region that receives a workpiece.

78. The system of claim 71 wherein the processing chamber includes a magnet positioned to orient material applied to a workpiece carried by the second carrier.

79. The system of claim 71 , further comprising a wireless communication link between the robot and the controller.

80. The system of claim 71 , further comprising a wireless communication device operatively coupled to the position sensor and movable with the position sensor along the guide path, the wireless communication device being coupled to the controller via a wireless communication link to transmit signals corresponding to the rotational orientation of the workpiece.

81. The system of claim 71 wherein the controller is programmed with instructions for: comparing the rotational orientation of the workpiece with a target value; determining a rotational orientation correction value; and directing a signal corresponding to the correction value.

82. A method for handling workpieces, comprising: identifying a first rotational orientation of a workpiece while the workpiece is carried by a transfer device; transferring the workpiece from the transfer device to a support positioned proximate to a processing chamber; rotating the workpiece from the first rotational orientation to a second rotational orientation by rotating the support, based at least in part on the identified first rotational orientation; and processing the workpiece at the processing chamber while the workpiece is carried by the support in the second rotational orientation.

83. The method of claim 82, further comprising: comparing the first rotational orientation of the workpiece with a target value; determining a rotational orientation correction value; and rotating the workpiece by the rotational orientation correction value from the first rotational orientation to the second rotational orientation.

84. The method of claim 82 wherein processing the workpiece includes applying conductive material to the workpiece and controlling an orientation of the conductive material with a magnet positioned proximate to the processing chamber.

85. The method of claim 82 wherein processing the workpiece includes depositing material on the workpiece without rotating the workpiece.

86. The method of claim 85 wherein processing the workpiece includes processing the workpiece while the workpiece is in a magnetic field and wherein depositing material includes depositing material on the workpiece in an orientation influenced by the magnetic field.

87. The method of claim 82, further comprising rotationally misaligning the workpiece by repeatedly gripping and releasing wafer prior to identifying the first rotational orientation of the workpiece.

88. The method of claim 82 wherein identifying the first rotational orientation includes identifying the first rotational orientation while the workpiece is carried at its edges.

89. A method for handling workpieces, comprising: identifying a first rotational orientation of a workpiece while the workpiece is carried by an end-effector of a transfer device; rotating the workpiece from the first rotational orientation to a second rotational orientation, based at least in part on the identified first rotational orientation; and processing the workpiece at the processing chamber while the workpiece is carried in the second rotational orientation.

90. The method of claim 89 wherein rotating the workpiece includes transferring the workpiece from the transfer device to a support positioned proximate to a processing chamber, and then rotating the support, and wherein processing the workpiece includes processing the workpiece while the workpiece is carried by the support in the second rotational orientation.

91. The method of claim 89 wherein the transfer device includes a base and links that are articulatable relative to the base, and wherein rotating the workpiece includes moving the links relative to the base, and moving the base relative to the process chamber until the workpiece has the second rotational orientation.

92. The method of claim 89, further comprising: comparing the first rotational orientation of the workpiece with a target value; determining a rotational orientation correction value; and rotating the workpiece by the rotational orientation correction value from the first rotational orientation to the second rotational orientation.

93. The method of claim 89 wherein processing the workpiece includes applying conductive material to the workpiece and controlling an orientation of the conductive material with a magnet positioned proximate to the processing chamber.

94. The method of claim 89 wherein processing the workpiece includes depositing material on the workpiece without rotating the workpiece.

95. The method of claim 94 wherein processing the workpiece includes processing the workpiece while the workpiece is in a magnetic field and wherein depositing material includes depositing material on the workpiece in an orientation influenced by the magnetic field.

96. The method of claim 89, further comprising rotationally misaligning the workpiece by repeatedly gripping and releasing wafer prior to identifying the first rotational orientation of the workpiece.

97. The method of claim 89, further comprising gripping the workpiece at its edges while identifying the first rotational orientation.

98. A processing system, comprising: a process chamber having a process location for processing workpieces; a support positioned to carry a workpiece at the process location; a transfer device movable relative to the support to move workpieces to and from the support; a magnet positioned adjacent to the process chamber to magnetically orient materials applied to the workpieces; and an enclosure positioned around the magnet to chemically isolate the magnet from chemicals delivered to and carried in the process chamber.

99. The tool of claim 98 wherein the enclosure includes a base below the magnet, walls connected to the base, and a top connected to the walls above the magnet, and wherein the walls and the top form a structural load path with the base.

100. The tool of claim 99 wherein the support and the process chamber are carried by the top.

101. The tool of claim 100 wherein the base has a fixed registration with a transport guide along which the transfer device moves, and wherein the top has a fixed registration with the base.

102. The tool of claim 99 wherein the base, walls and top are welded together and coated with a gas- and liquid-tight sealant.

103. The tool of claim 98 wherein the magnet includes first and second magnets positioned on opposing sides of the process chamber.

104. The tool of claim 103, further comprising a first magnetically conductive return path positioned between the first and second magnets within the enclosure, and a second magnetically conductive return path positioned between the first and second magnets external to the enclosure.

105. The tool of claim 104 wherein the second magnetically conductive return path is positioned between the transfer device and the first and second magnets to shield the transfer device from a magnetic field created by the magnets..

106. The tool of claim 98 wherein the transfer device is movable along a generally linear guide path, and wherein the tool further comprises a deck having a first portion on one side of the guide path that carries the process chamber, and a second portion on the other side of the guide path that carries an additional process chamber.

107. The tool of claim 106 wherein the first portion is at a first elevation and wherein the second portion is at a second elevation below the first elevation.

108. The tool of claim 98 further comprising a deck that carries the process chamber and the support, and wherein the deck is formed from a non-magnetic material.

109. A system for processing workpieces, comprising: a process chamber having a process location for processing workpieces; a support positioned to carry a workpiece at the process location; a transfer device movable relative to the support along a motion path to move workpieces to and from the support; a magnet positioned adjacent to the process chamber to magnetically orient materials applied to the workpieces; and a magnetically conductive shield positioned between the magnet and the motion path to shield the transfer device from the magnetic field of the magnet.

110. The tool of claim 109 wherein the magnet includes two spaced-apart magnets, and wherein the shield is positioned transverse to the two magnets.

111. The tool of claim 110 wherein the shield is spaced apart from the two magnets.

112. The tool of claim 110, further comprising a deck carrying the process chamber, the support and the transfer device, and wherein the deck includes a wall positioned between the process chamber and the motion path, with the magnets positioned on one side of the wall and the shield spaced apart from the magnets and positioned on an opposite side of the wall.

113. The tool of claim 112 wherein the wall and the shield are formed from different materials, and wherein the material forming the wall is generally nonmagnetic.

114. The tool of claim 112 wherein the wall forms at least a portion of a gas- and fluid-tight enclosure around the magnet.

115. The tool of claim 109 wherein the support includes a base, a workpiece carrier movable relative to the base, and a support motor coupled to the workpiece carrier to move the workpiece carrier relative to the base, and wherein the shield is a first shield, and wherein the tool further comprises a second shield positioned around the motor, between the motor and the magnet.

116. A system for processing workpieces, comprising: a process chamber having a process location for processing workpieces; a support positioned to carry a workpiece at the process location; a transfer device movable relative to the support along a motion path to move workpieces to and from the support; first and second magnets positioned on first and second opposing sides of the process chamber to magnetically orient materials applied to the workpieces; and first and second magnetically conductive return paths positioned on opposing third and fourth sides of the process chamber to orient the magnetic field of the magnets generally parallel to the return paths.

117. The tool of claim 116 wherein the first return path includes a first magnetically conductive member in contact with the first and second magnets, and wherein the second return path includes a second magnetically conductive member spaced apart from the first and second magnets and spaced apart from the first magnetically conductive member.

118. The tool of claim 116, further comprising a deck carrying the process chamber, the support and the transfer device, and wherein the deck includes a wall positioned between the process chamber and the motion path, with the first and second magnets positioned on one side of the wall and the second return path spaced apart from the magnets and positioned on an opposite side of the wall.

119. The tool of claim 118 wherein the wall and the shield are formed from different materials, and wherein the material forming the wall is generally nonmagnetic.

120. A method for processing workpieces, comprising: moving a workpiece from a transfer device to a support; carrying the workpiece with the support at a process location of a process vessel; processing the workpiece at the process location while orienting material in the process chamber with a magnet positioned proximate to the process chamber; and shielding the transfer device from a magnetic field emanating from the magnet with a magnetically conductive shield positioned between the magnet and the transfer device.

121. The method of claim 120 wherein the magnet includes two magnets positioned on opposing sides of the process chamber, and wherein the method further comprises orienting magnetic field lines at the process location with the magnetically conductive shield.

122. The method of claim 120, further comprising sealing the magnet from chemicals delivered to and carried in the process chamber.

123. A method for processing workpieces, comprising: moving a workpiece from a transfer device to a support; carrying the workpiece with the support at a process location of a process chamber, the process location being between first and second magnets; processing the workpiece at the process location while orienting material in the process chamber with the first and second magnets; and orienting a magnetic field between the first and second magnets with first and second magnetically conductive return paths positioned between the first and second magnets, and with the process location being between the first and second return paths.

124. The method of claim 123 wherein processing the workpiece includes depositing magnetically-sensitive material on the workpiece.

125. The method of claim 124, further comprising agitating processing liquid in the process chamber proximate to the process location by activating an agitator with an agitator motor that is shielded from the magnetic field.

126. The method of claim 123 wherein orienting the magnetic field includes orienting the magnetic field with a first magnetically conductive return path located within a sealed enclosure that also contains the magnet, and with a second magnetically conductive return path located external to the sealed enclosure.

127. A method for manufacturing a tool for processing workpieces, comprising: positioning a processing chamber along a transfer device guide path; locating a transfer device for movement along the guide path, the transfer device having a first carrier; positioning a workpiece support proximate to the processing chamber, the support having a second carrier accessible to the first carrier of the transfer device; positioning a magnet at the processing chamber to orient magnetic materials carried in the processing chamber; and positioning a magnetically conductive shield between the magnet and the guide path to direct magnetic field lines away from the transfer device.

128. The method of claim 127 wherein positioning the processing chamber includes carrying the processing chamber at a deck of the tool, and wherein positioning the workpiece support includes carrying the workpiece support at the deck of the tool.

129. The method of claim 127 wherein positioning a workpiece support includes positioning a workpiece support having a magnetically shielded motor coupled to the second carrier.

130. The method of claim 127, further comprising positioning the magnet in a sealed enclosure proximate to the processing chamber.

131. The method of claim 130, further comprising positioning the magnetically conductive shield external to the enclosure.