US20080003931A1

US20080003931A1 - System and method for in-situ head rinse

Info

Publication number: US20080003931A1
Application number: US11/562,811
Authority: US
Inventors: Antoine Manens; Alain Duboust; Paul Butterfield; Yan Wang; Shi-Ping Wang; Zhihong Wang; Andrew Nagengast; Wei-Yung Hsu; Liang-Yuh Chen
Original assignee: Individual
Current assignee: Applied Materials Inc
Priority date: 2005-11-22
Filing date: 2006-11-22
Publication date: 2008-01-03

Abstract

A carrier head and a method of cleaning the carrier head are disclosed. The carrier head may have one or more openings through a sidewall that extend into a cavity within the carrier head using a fluid passage. The openings may each have a lip. The lip may have a chamfered edge. Additionally, a fluid passage may slope generally downward from the openings to the cavity. The chamfered lips and the sloped fluid passage reduce back splashing and help ensure that sufficient rinsing fluid reaches the cavity to rinse polishing fluid and particles from the carrier head. The present invention relates to carrier heads for polishing or planarizing semiconductor substrates by chemical mechanical polishing (CMP) or electrochemical mechanical polishing (ECMP). The cavities in the carrier head are cleaned by rinsing fluid (i.e., liquid or gas) from inside the cavity towards a substrate receiving side of the carrier head.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Patent Application Ser. No. 60/738,775, filed Nov. 22, 2005, and U.S. Provisional Patent Application Ser. No. 60/759,142, filed Jan. 13, 2006, which are both herein incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention
Embodiments of the present invention generally relate to a carrier head for a chemical mechanical polishing system and a method of cleaning a carrier head.
2. Description of the Related Art
Chemical mechanical planarization, or chemical mechanical polishing (CMP), is a common technique used to planarize substrates. In conventional CMP techniques, a substrate carrier or polishing head is mounted on a carrier assembly and positioned in contact with the polishing article in a CMP apparatus. The polishing article and the substrate are moved relative to each other resulting in polishing or rubbing movement between the surface of the substrate and the polishing article.
As part of the manufacturing process of semiconductor devices, semiconductor substrates are increasingly being polished by CMP. Generally, the substrate to be polished is mounted on a substrate carrier which holds the substrate using a combination of vacuum suction or other means and, most often, the substrate backing pad to contact the rear side of the substrate. The retaining lip or ring is generally provided around the edge of the substrate to keep the substrate contained under the substrate carrier.
In a typical operation, the substrates may be sequentially polished at two, three or more polishing stations. Thereby, a multi-step polishing process in which, for example, a rough polish is followed by two successively finer polishes is applied. One method of achieving increasingly fine polishing is to use slurries having different characteristics or particle sizes at the different polishing stations. Cross-contamination of slurries between different platens is a concern. Therefore, it would be beneficial to ensure that intermixing of polishing slurries of different chemistries is kept to a minimum.
For ease of description and understanding, the following description will refer to substrates, which include but are not limited to semiconductor wafers, semiconductor workpieces, optical planks, memory disks and the like. The present invention may be applied to any generally disc shaped workpiece.

SUMMARY OF THE INVENTION

A carrier head and a method of cleaning the carrier head are disclosed. The carrier head may have one or more openings through a sidewall that extend into a cavity within the carrier head using a fluid passage. The openings may each have a lip. The lip may have a chamfered edge. Additionally, a fluid passage may slope generally downward from the openings to the cavity. The chamfered lips and the sloped fluid passage reduce back splashing and help ensure that sufficient rinsing fluid reaches the cavity to rinse polishing fluid and particles from the carrier head. The present invention relates to carrier heads for polishing or planarizing semiconductor substrates by CMP or electrochemical mechanical polishing (ECMP). The cavities in the carrier head are cleaned by rinsing fluid (i.e., liquid or gas) from inside the cavity towards a substrate receiving side of the carrier head.
In one embodiment, a carrier head is described comprising a backing assembly, a retaining ring, wherein a cavity is present between the retaining ring and the backing assembly, and a fluid rinsing system for rinsing the cavity.
In another embodiment, a carrier head is described comprising a top surface, a side surface substantially perpendicular to the top surface, and a fluid passage extending into the carrier head through the side surface to a cavity.
In yet another embodiment, a carrier head cleaning method is described comprising flowing a cleaning fluid through at least one opening in the carrier head, wherein the cleaning fluid flows to a cavity within the carrier head, the opening and the cavity are coupled together by a fluid passageway having sidewalls, and at least one sidewall of the fluid passageway is sloped from the opening toward the cavity.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.
FIG. 1 is a plan view of an ECMP system.
FIG. 2 is a sectional view of one embodiment of a first ECMP station of the system of FIG. 1.
FIG. 3 is a side view of the carrier head according to one embodiment of the invention.
FIG. 4A is a cross sectional view of the carrier head shown in FIG. 3.
FIG. 4B is another embodiment of a fluid passage for a carrier head.
FIG. 4C is yet another embodiment of a fluid passage for a carrier head.
FIG. 5A is a schematic side view of a portion of a carrier head including a fluid rinsing system for cleaning a cavity formed in the carrier head according to the present invention.
FIG. 5B is a schematic side view of a fluid passage in a system according to another embodiment of the present invention.
FIG. 6 is a schematic side view of a portion of a carrier head of another embodiment of a rinsing system according to the present invention.
To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements disclosed in one embodiment may be beneficially utilized on other embodiments without specific recitation.

DETAILED DESCRIPTION

A carrier head and a method of cleaning the carrier head are disclosed. The carrier head may have one or more openings through a sidewall that extend into a cavity within the carrier head using a fluid passage. The openings may each have a lip. The lip may have a chamfered edge. Additionally, a fluid passage may slope generally downward from the openings to the cavity. The chamfered lips and the sloped fluid passage reduce back splashing and help ensure that sufficient rinsing fluid reaches the cavity to rinse polishing fluid and particles from the carrier head. The present invention relates to carrier heads for polishing or planarizing semiconductor substrates by CMP or ECMP. The cavities in the carrier head are cleaned by rinsing fluid (i.e., liquid or gas) from inside the cavity towards a substrate receiving side of the carrier head.
FIG. 1 is a plan view of one embodiment of a planarization system 100 having an apparatus for electrochemically processing a substrate. The exemplary system 100 may include a factory interface 102, a loading robot 104, and a planarizing module 106. The loading robot 104 may be disposed proximate the factory interface 102 and the planarizing module 106 to facilitate the transfer of substrates 122 therebetween.
A controller 108 may be provided to facilitate control and integration of the modules of the system 100. The controller 108 may include a central processing unit (CPU) 110, a memory 112, and support circuits 114. The controller 108 may be coupled to the various components of the system 100 to facilitate control of, for example, the planarizing, cleaning, and transfer processes.
The factory interface 102 may include a metrology module 190, a cleaning module 116 and one or more wafer cassettes 118. An interface robot 120 may be employed to transfer substrates 122 between the wafer cassettes 118, the cleaning module 116 and an input module 124. The input module 124 may be positioned to facilitate transfer of substrates 122 between the planarizing module 106 and the factory interface 102 by grippers. In one embodiment, the grippers may be vacuum grippers. In another embodiment, the grippers may be mechanical clamps.
The metrology module 190 may be a non-destructive measuring device suitable for providing a metric indicative of the thickness profile of a substrate. The metrology module 190 may include eddy sensors, an interferometer, a capacitance sensor and other suitable devices. Examples of suitable metrology modules include iScan™ and iMap™ substrate metrology modules, available from Applied Materials, Inc. The metrology module 190 provides the metric to the controller 108 wherein a target removal profile is determined for the specific thickness profile measured from the substrate.
The planarizing module 106 may include at least a first ECMP station 128, disposed in an environmentally controlled enclosure 188. Examples of planarizing modules 106 that can be adapted to benefit from the invention include MIRRA®, MIRRA MESA™, REFLEXION®, REFLEXION® LK, and REFLEXION LK Ecmp™ CMP Systems, all available from Applied Materials, Inc. of Santa Clara, Calif. Other planarizing modules, including those that use processing pads, planarizing webs, or a combination thereof, and those that move a substrate relative to a planarizing surface in a rotational, linear or other planar motion may also be adapted to benefit from the invention.
In the embodiment depicted in FIG. 1, the planarizing module 106 includes the ECMP station 128, a CMP or ECMP station 130, and a CMP station 132. According to a further embodiment, the embodiment of FIG. 1 may also be equipped with three CMP polishing stations.
The exemplary planarizing module 106 may also include a transfer station 136 and a carousel 134 that are disposed on an upper or first side 138 of a machine base 140. In one embodiment, the transfer station 136 includes an input buffer station 142, an output buffer station 144, a transfer robot 146, and a load cup assembly 148. The input buffer station 142 receives substrates from the factory interface 102 by means of the loading robot 104. The loading robot 104 may also be utilized to return polished substrates from the output buffer station 144 to the factory interface 102. The transfer robot 146 is utilized to move substrates 122 between the buffer stations 142, 144 and the load cup assembly 148.
In one embodiment, the transfer robot 146 includes two gripper assemblies, each having pneumatic gripper fingers that hold the substrate 122 by the substrate's edge. The transfer robot 146 may simultaneously transfer a substrate to be processed from the input buffer station 142 to the load cup assembly 148 while transferring a processed substrate from the load cup assembly 148 to the output buffer station 144. An example of a transfer station that may be used to advantage is described in U.S. Pat. No. 6,156,124, which is herein incorporated by reference in its entirety.
The carousel 134 may be centrally disposed on the base 140. The carousel 134 may include a plurality of arms 150, each supporting a carrier head assembly 152. Two of the arms 150 depicted in FIG. 1 are shown in phantom such that the transfer station 136 and a planarizing surface 126 of the first ECMP station 128 may be seen. The carousel may be indexable such that the carrier head assemblies 152 may be moved between the planarizing stations 128, 130, 132 and the transfer station 136. One carousel that may be utilized to advantage is described in U.S. Pat. No. 5,804,507, which is hereby incorporated by reference in its entirety. Each of the polishing stations has a platen and a polishing pad. An electrolyte or a slurry is provided to the polishing pads through slurry arms 170, respectively. Generally, the methods described below may be conducted with a system as described above.
FIG. 2 depicts a sectional view of one of the planarizing head assemblies 152 positioned over the first ECMP station 128. The second and third ECMP stations 130, 132 may be similarly configured. The planarizing head assembly 152 generally comprises a drive system 202 coupled to a planarizing head 204. The drive system 202 generally provides at least rotational motion to the planarizing head 204. The planarizing head 204 additionally may be actuated toward the first ECMP station 128 such that the substrate 122 retained in the planarizing head 204 may be disposed against the planarizing surface 126 of the first ECMP station 128 during processing. The drive system 202 is coupled to the controller 108 that provides a signal to the drive system 202 for controlling the rotational speed and direction of the planarizing head 204.
In one embodiment, the planarizing head may be a TITAN HEAD™ or TITAN PROFILER™ wafer carrier manufactured by Applied Materials, Inc. The planarizing head 204 may comprise a housing 214 and retaining ring 224 that defines a center recess in which the substrate 122 is retained. The retaining ring 224 circumscribes the substrate 122 disposed within the planarizing head 204 to prevent the substrate from slipping out from under the planarizing head 204 while processing. The retaining ring 224 may be made of plastic materials such as polyphenylene sulfide (PPS), polyetheretherketone (PEEK), and the like, or conductive materials such as stainless steel, Cu, Au, Pd, and the like, or some combination thereof. It is further contemplated that a conductive retaining ring 224 may be electrically biased to control the electric field during ECMP. Conductive or biased retaining rings tend to slow the polishing rate proximate the edge of the substrate. It is contemplated that other planarizing heads may be utilized.
The first ECMP station 128 may include a platen assembly 230 that is rotationally disposed on the base 140. The platen assembly 230 may be supported above the base 140 by a bearing 238 so that the platen assembly 230 may be rotated relative to the base 140. An area of the base 140 circumscribed by the bearing 238 is open and provides a conduit for the electrical, mechanical, pneumatic, control signals and connections communicating with the platen assembly 230.
Conventional bearings, rotary unions and slip rings, collectively referred to as rotary coupler 276, are provided such that electrical, mechanical, fluid, pneumatic, control signals and connections may be coupled between the base 140 and the rotating platen assembly 230. The platen assembly 230 may be coupled to a motor 232 that provides the rotational motion to the platen assembly 230. The motor 232 is coupled to the controller 108 that provides a signal for controlling for the rotational speed and direction of the platen assembly 230.
A top surface 260 of the platen assembly 230 supports a processing pad assembly 222 thereon. The processing pad assembly may be retained to the platen assembly 230 by magnetic attraction, vacuum, clamps, adhesives and the like.
A plenum 206 is defined in the platen assembly 230 to facilitate uniform distribution of electrolyte to the planarizing surface 126. A plurality of passages, described in greater detail below, may be formed in the platen assembly 230 to allow electrolyte, provided to the plenum 206 from an electrolyte source 248, to flow uniformly though the platen assembly 230 and into contact with the substrate 122 during processing. It is contemplated that different electrolyte compositions may be provided during different stages of processing.
The processing pad assembly 222 may include an electrode 292 and at least a planarizing portion 290. The electrode 292 may be comprised of a conductive material, such as stainless steel, copper, aluminum, gold, silver and tungsten, among others. The electrode 292 may be solid, impermeable to electrolyte, permeable to electrolyte or perforated. At least one contact assembly 250 extends above the processing pad assembly 222 and is adapted to electrically couple the substrate being processed on the processing pad assembly 222 to the power source 242. The electrode 292 may also be coupled to the power source 242 so that an electrical potential may be established between the substrate and electrode 292.
A meter 240 may be provided to detect a metric indicative of the electrochemical process. The meter may be coupled or positioned between the power source 242 and at least one of the electrode 292 or contact assembly 250. The meter may also be integral to the power source 242. In one embodiment, the meter is configured to provide the controller 108 with a metric indicative of processing, such as charge, current and/or voltage. This metric may be utilized by the controller 108 to adjust the processing parameters in-situ or to facilitate endpoint or other process stage detection.
A window 246 may be provided through the pad assembly 222 and/or platen assembly 230, and is configured to allow a sensor 254, positioned below the pad assembly 222, to sense a metric indicative of polishing performance. In one embodiment, the sensor 254 may be an eddy current sensor. The metric, provided by the sensor 254 to the controller 108, provides information that may be utilized for processing profile adjustment in-situ, endpoint detection or detection of another point in the electrochemical process. In one embodiment, the sensor 254 may be an interferometer capable of generating a collimated light beam, which during processing, is directed at and impinges on a side of the substrate 122 that is being polished. The interference between reflected signals is indicative of the thickness of the conductive layer of material being processed. One sensor that may be utilized to advantage is described in U.S. Pat. No. 5,893,796, which is hereby incorporated by reference in its entirety.
Embodiments of the processing pad assembly 222 suitable for removal of conductive material from the substrate 122 may generally include a planarizing surface 126 that is substantially dielectric. Other embodiments of the processing pad assembly 222 suitable for removal of conductive material from the substrate 122 may include a planarizing surface 126 that is substantially conductive. At least one contact assembly 250 may be provided to couple the substrate to the power source 242 so that the substrate may be biased relative to the electrode 292 during processing. Apertures 210, formed through the planarizing layer 290 and the electrode 292 and any elements disposed below the electrode, allow the electrolyte to establish a conductive path between the substrate 112 and electrode 292.
In one embodiment, the planarizing portion 290 of the processing pad assembly 222 is a dielectric, such as polyurethane. Examples of processing pad assemblies that may be adapted to benefit from the invention are described in United States Patent Publication No. 2004/0023610 A1 and United States Patent Publication No. 2004/0020789 A1, both of which are hereby incorporated by reference in their entireties.
During polishing of the substrate on one polishing pad using slurry, the chemistries of the slurry may contaminate the carrier head. In the event that chemistries of the slurry are not compatible to a second slurry provided on a second platen, cross-contamination may occur when a substrate is sequentially polished on the first platen and then on a second platen. Cross-contamination should particularly be avoided if the chemistries of the first slurry are incompatible with the chemistries of the second slurry. Incompatibility can be characterized as a large difference in polarization voltage, or by precipitation when mixed. Independent of the specific example given above, any cross-contamination of a second slurry with chemistry of the first slurry should, in general, be avoided. Therefore, a rinsing system according to the present invention is provided.
The cleaning of the carrier head to avoid cross-contamination due to transfer of a substrate from a first to a second platen may be conducted while the carrier head with the substrate is still positioned above the first polishing station. Alternatively, rinsing may be conducted while the carrier head with the substrate positioned therein is transferred from the first polishing station to the second polishing station. Even though cross-contamination may occur if the rinsing is conducted while the carrier head and the substrate are positioned over the second polishing station, an appropriate method can be conducted over the second polishing station. For example, rinsing may be conducted with appropriate chemistry or with a sufficient amount of fluid such that detrimental effects on the slurry of the further polishing station can be prevented. According to a further alternative, as described below, the head rinse of any of the embodiments described herein may be conducted in parallel to the pad cleaning during which the pad is rinsed. Thereby, any cross contamination by rinsing over the platen of the second polishing station is removed from the platen of the second polishing station.
According to another embodiment, the head rinse of any of the embodiments described herein may be conducted in parallel with the wafer rinse, during which the head presses down on the wafer, while water or cleaning chemical is delivered on the pad.
Before a substrate is received by any of the carrier heads, the head may be rinsed. The rinsing may be performed before the substrate enters the load cup and the system. The cavities in the carrier head may be cleaned by rinsing fluid from inside the cavity towards a substrate receiving side of the carrier head. It may be possible that the head is additionally washed with a gap wash from below when the carrier head is located in the load cup.
After the substrate enters the system and is carried by the carrier head, the substrate is moved to the first platen. In one embodiment, the first polishing step may be an ECMP process. Thereby, an electrolyte, such as EP3.1 commercially available from Applied Materials Inc., may be used for the ECMP process. However, ECMP processes with other electrolytes or CMP processes may also be used. The carrier head may then be rinsed.
After the first polishing, the substrate may be moved by the carousel 134 to the second platen. A rinsing of the carrier head may take place over the second platen in addition to or in place of the rinsing at the first platen. The cavities inside the carrier head, especially the gap between the membrane and the retaining ring, may be rinsed from the side or from above. The cavities in the carrier head may be cleaned by rinsing fluid from inside the cavity towards a substrate receiving side of the carrier head.
The head rinse over the second platen may be conducted together with the pad wash of the second platen before polishing. The pad rinse or pad clean may be conducted by provided rinsing fluid on the platen and rotating the platen at high speed. In one embodiment, the platen may be rotated from about 60 to about 150 rpm. In another embodiment, the rinsing fluid for the pad rinse may be provided from about 8 to about 12 l/min. In another embodiment, the rinsing fluid may be provided at about 10 l/min.
After the pad clean and the head rinse have been conducted, the substrate may be polished on the second platen. The head rinse reduces the cross-contamination of, for example, electrolyte from the first platen to the slurry on the second platen.
After the polishing step on the second platen, the pad and the substrate may be rinsed over the second platen. In one embodiment, a head rinse may be conducted over the second platen before the substrate is moved to the next platen. Thereby, a cross-contamination of the slurry of the second platen to the slurry of the third platen may be reduced.
According to a further alternative, the substrate may first be moved to the third platen and a pad clean, a substrate rinse, and/or a head rinse may be conducted over the third platen. After the polishing step on the third platen, a post rinse in form of a head rinse according to any of the above described embodiments on the third platen may be conducted. In one embodiment, slurry 66XX from Cabot may be used on the third platen. Additionally or alternatively to the post rinse, a rinsing in the load cup before transfer of the substrate to the factory interface may be conducted.
The rinsing steps described above may be conducted through a fluid passage in the side or a top of the carrier head body and/or the cover of the carrier head. Since the slurry is intended to be removed from the cavity and the fluid passage, an opening from the substrate receiving side of the carrier head is less effective. The fluid passage may be adapted to deliver the rinsing fluid, such as DI water, in the cavity at a top side of the membrane unit which is opposite to the wafer receiving side or a side surface. The rinsing fluid should typically not be provided from the substrate receiving side of the membrane unit as the only rinse because undesirable contaminants may remain.
FIG. 3 is a side view of a carrier head 300 according to one embodiment of the invention. The carrier head 300 comprises a cover 302 and a retaining ring 304. Through the sidewall of the cover 302, an opening having lip portions 306, 308, 310, and 312 are present. The opening extends to a cavity 322 within the carrier head 300. The opening extends from the lip portions 306, 308, 310, and 312 to the cavity 322 by a fluid passage bound by sidewalls 314, 316, 318, and 320. The lip portions 306, 308, 310, and 312 may be chamfered to slope generally into the opening. The chamfering may help rinsing fluid sprayed at the opening to flow through the opening and into the cavity 322 rather than splash back out of the opening. Additionally, the sidewalls 314, 316, 318, and 320 slope generally downward from the lip portions 306, 308, 310, and 312 of the opening to the cavity 322 to minimize the amount of rinsing fluid splashed back out of the opening.
It is to be understood that while only one opening has been shown in FIG. 3, multiple openings may be present. In one embodiment, eight openings may be present. In another embodiment, sixteen openings may be present. In yet another embodiment, thirty-two openings may be present. The number of openings is limited only by the structural integrity of the carrier head. The number of openings should be large enough to ensure adequate cleaning of the carrier head, but not so large as to weaken the structure of the carrier head and cause the carrier head to bow due to the inability to support the weight of itself and a substrate.
FIG. 4A is a cross sectional view of the carrier head shown in FIG. 3 taken along line 4-4. FIG. 3 shows a substrate 324 coupled with a membrane unit 326. A carrier 328 couples the membrane unit 326 to the carrier head 300. The carrier 328 may be coupled to the cover 302 by an interface 330. The interface 330 may be a gap having flexures or other conventional coupling mechanisms known in the art.
As may be seen from FIG. 4A, the sidewalls 314, 316, and 320 shown slope downward from the opening to the cavity 322. The cavity 322 is coupled with a fluid passage 332 so that cleaning fluid enters the opening, travels to the cavity 322, and out the fluid passage 332. The lip portions 306, 310, and 312 are shown as chamfered surfaces.
FIG. 4B is another embodiment of a fluid passage for a carrier head. In the embodiment shown in FIG. 4B, the fluid passage has an hourglass shape. The fluid passage penetrates the cover 302 from the side surface, and extends through the carrier 328 from side surface into the cavity. The hourglass cross-section may permit the rinsing fluid to spray into the cavity.
A further embodiment of the fluid passage is shown in FIG. 4C. Therein, the fluid passage is reduced in cross-section from the outer side surface to the cavity in order to provide a jet into the cavity. Fluid passages, as shown in FIGS. 4B and 4C, respectively, may be used for all carrier heads described in the present application. They may, however, particularly be used if the fluid is pressurized. If the fluid for rinsing the cavity is pressurized, a jet nozzle or other forms of the passage may be used to improve the cleaning mechanism for contaminating chemistry.
FIG. 5A shows another embodiment according to the present invention. The carrier head 500 includes a cover 540, a carrier 520, and a substrate backing assembly or membrane unit 530. Each of these components has a surface 540 a, 520 a, and 530 a, respectively, facing the substrate 502. Further, these components have a surface 540 b, 520 b, and 530 b, respectively, opposing the corresponding one of surfaces 540 a, 520 a, and 530 a. Further, there are side surfaces towards the side 500 c of the carrier head 500. The cover 540, the carrier 520, and the membrane unit 530 may be disc-shaped units adapted to hold a circular substrate. The carrier head 500 further includes a retaining ring 535 that surrounds the membrane and the workpiece. The retaining ring 535 has an internal diameter only slightly larger than the diameter of the workpiece. The retaining ring serves, on the one hand, to constrain the workpiece properly positioned under the carrier head. On the other hand, it might flatten a polishing pad in the vicinity of the wafer's edge during polishing.
For constructional purposes, generally, there is a small space 510 between the membrane unit 530 and the retaining ring 535. Further, space 512 may be present at least behind a part of the membrane unit 530. These cavity-forming spaces or gaps may be required to vertically move the substrate 502 with respect to the retaining ring 535. A vertical movement of the membrane unit 530 and, thereby the substrate 510 with respect to the retaining ring 535 is desired, for example, to adjust the polishing pressure.
FIG. 5A shows a fluid passage for rinsing a fluid, such as deionized water, or other chemistry from the top of the carrier head 500 through the cavity formed by gap 510 and space 512. Thus, chemistry stemming from the first slurry, which entered the cavity, can be removed. Independent of a specific embodiment, the cavity to be rinsed includes at least a gap 510. It may further include a space 512.
The rinsing system in FIG. 5A includes the fluid passage 522. The fluid passage 522 penetrates cover 540 from surface 540 b. The passage extends from top to bottom in FIG. 5A. The cavity formed of gap 510 and space 512 is defined around the entire perimeter of the carrier head. Therefore, a plurality of fluid passages 522 may be provided along the perimeter of the carrier head to rinse the cavity extending around the perimeter. In the event the rinsing fluid is a liquid, the liquid may be sprayed over the cover of the carrier head with a spray arm included in the polishing station. The liquid may then flow through the cavity by flowing through the fluid passage 522 and then through the cavity 510, 512 due to the force of gravity. Alternatively, if an external nozzle is provided to the passage 522, the rinsing system can be pressurized as well. A pressure of up to 1000 psi or more may be used. In one embodiment, a pressure of about 30 psi may be used. FIG. 5A further shows a flexure 524 between cover 540 and carrier 520 to guide the fluid passage 522 between these components. The flexure can be adapted to allow any desired movements between the cover and the carrier. In one embodiment, a flow rate through the entire cavity of the carrier head may be between about 1 l/min and about 10 l/min. In another embodiment, a flow rate between 1 l/min and about 4 l/min may be used.
A detailed side view of an embodiment of a fluid passage 522 is shown in FIG. 5B. Fluid passage 522 may particularly be used with the carrier head 500 shown in FIG. 5A. However, it may also be used for other carrier heads of other embodiments. Fluid passage 522 provides, for example, a liquid from top to bottom into the contaminated space 512. FIG. 5B shows that the junction between the fluid passage and the space 512 is smoothly shaped to have a gentle flow into the cavity to be rinsed. A flow along the surface of the cavity improves the removal of any contamination located on the surface of the cavity.
Alternatively, a sparger or any other means appropriate to improve the removal of chemistry on the interior walls of the cavity can be applied. For example, the fluid passage 522 can be shaped to provide a helix type flow of the liquid rinsing into cavity 510, 512.
A further embodiment of a carrier head 600 will now be described with respect to FIG. 6. In addition to cover 640, carrier 620, surfaces 640 a, 640 b, 630 a, 630 b, 620 a, 620 b, substrate 602, retaining ring 635, and membrane unit/backing assembly 630, FIG. 6 shows spindle 650. During polishing, the carrier head 600 is rotated with spindle 650. FIG. 6 shows a fluid passage 622, which is provided from an upper portion of spindle 650 into cover 640 and extending to cavity 610, 612. The spindle contains not only the pneumatic port required to inflate the polishing head, but also an additional port for rinsing fluid. According to another embodiment (not shown), fluid passage 622 may also extend through carrier 620.
In the event the fluid is provided through the spindle 650, no external spray arm is required. The fluid providing system is part of the carrier head itself. Thus, generally four variations may be employed. An external fluid providing system (spray arm) may provide the fluid in the cavity from top, an external fluid providing system (spray arm) may provide the fluid in the cavity from the side, an internal fluid providing system (through spindle) may provide the fluid in the cavity from top, and an internal fluid providing system (though spindle) may provide the fluid in the cavity from the side of the cavity.
As already discussed with respect to the previous embodiments, gap 610 and space 612 extend mainly around the entire perimeter of the carrier head. Thus, a plurality of fluid passages 622 may be provided. The fluid passages 622 may be equally spaced around the perimeter.
The system shown in FIG. 1 includes the slurry arms 170. The different embodiments of the polishing head include fluid passages. For systems according to the present invention, the slurry arms 170 may include, besides the spray unit for spraying the slurry or the electrolyte on the pad, a further nozzle to spray the rinsing fluid for the head rinse in the fluid passages of the carrier head. Thus, the spray arm for providing the rinsing fluid to the carrier head is stationarily mounted with respect to the carried head. A jet of rinsing fluid, such as DI water, is oriented towards the openings of the fluid passages. During rotation of the carrier head, the openings of the fluid passages pass sequentially by the spray arm spraying the rinsing fluid towards the carrier head. While the opening of the fluid passages provided around the carrier head pass by the spraying nozzle, the rinsing fluid is inserted in the fluid passages on top or at the side of the carrier head and is thereby delivered in the carrier head to rinse the cavity from the side opposing the substrate receiving side.
Generally, the rinsing of the gap and the space by inserting the rinsing fluid through a fluid passage with an opening at the top or the side of the carrier head can be conducted over a platen, in-between a platen or in the load cup. Thereby, repeating rinsing at the various locations between the polishing steps may be conducted. Nevertheless, throughput has to be considered. The head rinse through the fluid passages from the side downward or from the top downward, can be used to keep the carrier head clean in general. This may, for example, be done as an alternative to or in addition to the gap wash from the bottom in the load cup. Whenever, a cleaning of the carried head is required with or without a substrate being attached to the carrier head, this additional rinsing of the carrier head may be conducted in the load cup, over a platen or in-between two platens. If the head rinse according to any of the embodiments should be combined with the gap wash from below, the carrier head would be required to be in the load cup where the gap wash from below is located.
Some of the detailed embodiments above refer to systems with ECMP and CMP platens. However, the carrier heads for rinsing the cavities from top down and the methods described above can also be used similarly for systems having only CMP processes. Any cross-contamination between slurries or between electrolytes and slurries or vice versa may be efficiently reduced by the carrier heads according to the invention and the methods according to the invention described herein.
While the foregoing is directed to embodiments of the invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof in the scope thereof is determined by the claims that follow.

Claims

1. A carrier head, comprising:

a backing assembly;

a retaining ring, wherein a cavity is present between the retaining ring and the backing assembly; and

a fluid rinsing system for rinsing the cavity.

2. The carrier head of claim 1, wherein the fluid rinsing system supplies fluid to at least one opening in the head extending to the cavity.

3. The carrier head of claim 2, wherein the at least one opening is positioned substantially perpendicular to a substrate receiving surface of the carrier head.

4. The carrier head of claim 2, wherein the at least one opening has a top wall that has a higher elevation on the carrier head than a top wall of the cavity.

5. The carrier head of claim 2, wherein the at least one opening comprises a lip portion having at least one chamfered edge.

6. The carrier head of claim 1, wherein the cavity is coupled with a plurality of openings.

7. A carrier head, comprising:

a top surface; and

a side surface substantially perpendicular to the top surface, wherein a fluid passage extends through the carrier head from the side surface to a cavity.

8. The carrier head of claim 7, wherein the fluid passage has a lip portion coupled with the side surface, the lip portion having at least one surface positioned at an angle relative to the side surface such that the lip portion slopes into the fluid passage.

9. The carrier head of claim 8, wherein the fluid passage comprises an upper surface and a lower surface, wherein the upper surface and the lower surface each slope downward from the lip portion to a cavity positioned opposite the lip portion.

10. The carrier head of claim 8, wherein the fluid passage comprises side surfaces, wherein the side surfaces converge toward the cavity positioned opposite the lip portion.

11. The carrier head of claim 10, wherein the cavity is coupled with a plurality of fluid passages.

12. The carrier head of claim 10, wherein an upper edge of the lip portion is at a higher elevation than a top wall of the cavity.

13. The carrier head of claim 7, further comprising:

a retaining ring; and

a backing assembly, wherein the cavity is present between the retaining ring and the backing assembly.

14. A carrier head cleaning method, comprising:

flowing a cleaning fluid through at least one opening in a carrier head, the cleaning fluid flowing to a cavity within the carrier head, wherein the opening and the cavity are coupled together by a fluid passageway having sidewalls, and at least one sidewall of the fluid passageway is sloped from the opening toward the cavity.

15. The method of claim 14, wherein the flowing is performed in a load cup.

16. The method of claim 14, wherein the flowing is performed over a platen.

17. The method of claim 14, further comprising:

rotating the carrier head during the flowing.

18. The method of claim 17, further comprising:

polishing a substrate at a first platen, wherein said flowing is performed over the first platen.

19. The method of claim 17, further comprising:

polishing a substrate at a first platen, wherein said flowing is performed over a platen different from said first platen.

20. The method of claim 14, wherein the at least one opening is substantially perpendicular to a substrate receiving surface of the carrier head.