WO2010094343A1

WO2010094343A1 - Bernoulli gripper

Info

Publication number: WO2010094343A1
Application number: PCT/EP2009/056322
Authority: WO
Inventors: Marco Galiazzo; Andrea Baccini
Original assignee: Applied Materials, Inc.
Priority date: 2009-02-23
Filing date: 2009-05-25
Publication date: 2010-08-26
Also published as: TW201110264A; ITUD20090042A1

Abstract

Embodiments of the present invention generally provide a device for handling substrates. The device includes a body having a substrate receiving surface surrounding a gas injection port and a gas exhaust port. A gas source is connected to the gas injection port. The gas exhaust port is one or more passages positioned near the substrate receiving surface and the gas injection port is one or more passages positioned away from the substrate receiving surface.

Description

BERNOULLI GRIPPER

BACKGROUND OF THE INVENTION Field of the Invention [0001] Embodiments of the present invention generally relate to a device for handling substrates during manufacturing processes. In particular, embodiments of the present invention relate to handling substrates in a system and process for screen printing a multiple layer pattern on a surface of the substrate. Description of the Related Art [0002] Solar cells are photovoltaic (PV) devices that convert sunlight directly into electrical power. Solar cells typically have one or more p-n junctions. Each p-n junction comprises two different regions within a semiconductor material where one side is denoted as the p-type region and the other as the n-type region. When the p-n junction of a solar cell is exposed to sunlight (consisting of energy from photons), the sunlight is directly converted to electricity through the PV effect. Solar cells generate a specific amount of electric power and are tiled into modules sized to deliver the desired amount of system power. Solar modules are joined into panels with specific frames and connectors. Solar cells are commonly formed on silicon substrates, which may be single or multicrystalline silicon substrates. A typical solar cell includes a silicon wafer, substrate, or sheet typically less than about 0.3 mm thick with a thin layer of n-type silicon on top of a p-type region formed on the substrate.

[0003] The PV market has experienced growth at annual rates exceeding 30% for the last ten years. Some articles suggest that solar cell power production world-wide may exceed 10 GWp in the near future. It is estimated that more than 95% of all solar modules are silicon wafer based. The high market growth rate in combination with the need to substantially reduce solar electricity costs has resulted in a number of serious challenges for inexpensively forming high quality solar cells. Therefore, one major component in making commercially viable solar cells lies in reducing the manufacturing costs required to form the solar cells by improving the device yield and increasing the substrate throughput. [0004] Screen printing has long been used in printing designs on objects, such as cloth or ceramics, and is used in the electronics industry for printing electrical component designs, such as electrical contacts or interconnects on the surface of a substrate. State of the art solar cell fabrication processes also use screen printing processes. In some applications, it is desirable to print contact lines on solar cell substrates having higher aspect ratios (i.e. ratio of line height to line width) than is possible with printing a single layer pattern to increase the current carrying capacity of the contacts. In order to meet this need, screen printing a double layered pattern has been attempted to increase the aspect ratio of the printed lines. However, the misalignment of a second layer of a screen printing pattern on an existing layer of the screen printing pattern due to errors in the positioning of the substrate on an automated transferring device, defects in the edge of the substrate, or shifting of the substrate on the automated transferring device can lead to poor device performance and low device efficiency. [0005] Solar cell substrates are typically fragile and vulnerable to breakage even from minimal mechanical shocks and torsional loads. Additionally, as manufacturing costs increase, there is a demand for thinner and thinner wafers (<150 microns) to maximize yield. However, thinner wafers crack more easily, and cracked wafers are not usable for solar cells. Although the wafers are protected in the completed cell, they are very fragile during manufacturing and therefore must be handled carefully. [0006] Therefore, there is a need for a screen printing apparatus for the production of solar cells, electronic circuits, or other useful devices that has an improved method of handling a substrate within the system.

SUMMARY OF THE INVENTION [0007] Embodiments of the present invention generally provide a device for handling substrates. The device includes a body having a substrate receiving surface surrounding a gas injection port and a gas exhaust port. A gas source is connected to the gas injection port. The gas exhaust port is one or more passages positioned near the substrate receiving surface and the gas injection port is one or more passages positioned away from the substrate receiving surface. [0008] In another embodiment of the invention, a method of handling a substrate is provided. The method includes placing a handling device over the substrate. The handling device includes a body having a substrate receiving surface surrounding a gas injection port and a gas exhaust port. A gas source is connected to the gas injection port. The gas exhaust port is one or more passages positioned near the substrate receiving surface and the gas injection port is one or more passages positioned away from the substrate receiving surface. The method includes creating a vacuum region above the substrate by flowing gas out of the gas injection port, over the substrate, towards the substrate receiving surface, and through the gas exhaust port. The method also includes sealing a portion surrounding the vacuum region by causing the substrate to contact the substrate receiving surface and moving the substrate. [0009] In yet another embodiment of the present invention, a screen printing system is provided. The screen printing system includes a rotary actuator having a printing nest disposed thereon and movable between a first position, a second position, and a third position, an input conveyor positioned to load a substrate onto the printing nest in the first position, and a pre-centering unit having a non- contact substrate handling device positioned to center a substrate on the input conveyor. The non-contact handling device includes a body having a substrate receiving surface surrounding a gas injection port and a gas exhaust port. A gas source is connected to the gas injection port. The gas exhaust port is one or more passages positioned near the substrate receiving surface and the gas injection port is one or more passages positioned away from the substrate receiving surface. The screen printing system also includes a screen printing chamber having an adjustable screen printing device disposed therein where the screen printing chamber is positioned to print a pattern onto the substrate when the printing nest is in the second position. The pattern comprises a conductive structure of thin lines. Additionally, an exit conveyor is positioned to unload the substrate when the printing nest is in the third position. A system controller comprising software is configured to actuate the non-contact substrate handling device for moving the substrate and for centering the substrate on the input conveyor. [0010] In yet another embodiment of the present invention, a screen printing system is provided. The screen printing system includes a rotary actuator having a printing nest disposed thereon and movable between a first position, a second position, and a third position, an input conveyor positioned to load a substrate onto the printing nest in the first position, and a centering conveyor positioned to load a substrate on the input conveyor. The centering conveyor has a non-contact substrate handling device to center a substrate on the centering conveyor. The non-contact handling device includes a body having a substrate receiving surface surrounding a gas injection port and a gas exhaust port. A gas source is connected to the gas injection port. The gas exhaust port is one or more passages positioned near the substrate receiving surface and the gas injection port is one or more passages positioned away from the substrate receiving surface. The screen printing system also includes a screen printing chamber having an adjustable screen printing device disposed therein where the screen printing chamber is positioned to print a pattern onto the substrate when the printing nest is in the second position. The pattern comprises a conductive structure of thin lines. Additionally, an exit conveyor is positioned to unload the substrate when the printing nest is in the third position. A system controller comprising software is configured to actuate the non-contact substrate handling device for moving the substrate and for centering the substrate on the input conveyor. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] 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. [0012] Figure IA is a schematic isometric view of a system that may be used in conjunction with embodiments of the present invention to form multiple layers of a desired pattern.

[0013] Figure IB is a schematic top plan view of the system in Figure IA. [0014] Figure 2 A is a plan view of a front surface, or light receiving surface, of a solar cell substrate. [0015] Figure 2B is a schematic cross-sectional view of a portion of a solar cell substrate having a properly aligned second layer printed atop a first layer.

[0016] Figure 2C is a schematic isometric view of a solar cell substrate illustrating misalignment of screen printing layers.

[0017] Figure 3 is a schematic isometric view of the front side of a non-contact substrate handling device according to one embodiment of the present invention. [0018] Figure 4 is a schematic isometric view of the back side of a non-contact substrate handling device according to one embodiment of the present invention. [0019] Figure 5 A illustrates a schematic cross-sectional view of a substrate and one embodiment of the non-contact substrate handling device before the device handles the substrate.

[0020] Figure 5B is a schematic cross-sectional view of a substrate and one embodiment of the non-contact substrate handling device during non-contact handling of the substrate. [0021] Figure 6 is a schematic diagram of an operational sequence for non- contact handling of a substrate according to one embodiment of the present invention.

[0022] Figure 7 is a top plan view of a system that may be used in conjunction with embodiments of the present invention to form multiple layers of a desired pattern on a substrate.

DETAILED DESCRIPTION

[0023] Embodiments of the present invention provide an device and method for handling substrates during processing, such as in a screen printing system, that utilize an improved substrate handling device that may be used for transferring, aligning, and screen printing processes that can improve the device yield performance and cost-of-ownership (CoO) of a substrate processing line. In one embodiment, the screen printing system, hereafter system, is adapted to perform a screen printing process within a portion of a crystalline silicon solar cell production line in which a substrate is patterned with a desired material in two or more layers and is then processed in one or more subsequent processing chambers. The subsequent processing chambers may be adapted to perform one or more bake steps and one or more cleaning steps. In one embodiment, the system is a module positioned within the SoftlineTM tool available from Baccini S.p.A., which is owned by Applied Materials, Inc. of Santa Clara, California. While the discussion below primarily discusses the processes of screen printing a pattern, such as an interconnect or contact structure, on a surface of a solar cell device this configuration is not intended to be limiting as to the scope of the invention described herein. [0024] It should be noted that although contact between the substrate and the handling device is used to keep the substrate stable and prevent spinning of the substrate, the term "non-contact" is often used to describe the handling device because the actual gripping force is not by mechanical contact. [0025] Figure IA is a schematic isometric view and Figure IB is a schematic top plan view illustrating one embodiment of a screen printing system, or system 100, that may be used in conjunction with embodiments of the present invention to form multiple layers of a desired pattern on a surface of a solar cell substrate 150. In one embodiment, the system 100 comprises an incoming conveyor 111, a rotary actuator assembly 130, a screen print chamber 102, an outgoing conveyor 112, and a drying chamber 200. The incoming conveyor 111 may be configured to receive a substrate 150 from an input device, such as an input conveyor 113, and transfer the substrate 150 to a printing nest 131 coupled to the rotary actuator assembly 130. In one embodiment of the invention, a non-contact substrate handling unit 175 on centering conveyor 170 may be used to pre-center a substrate as it passes between input conveyor 113 and incoming conveyor 111. In another embodiment, incoming conveyor 111 may pass through a pre- centering unit 160 having a non-contact substrate handling device to pre-center a substrate 150 as it is transferred from the incoming conveyor 111 to the printing nest 131.

[0026] The outgoing conveyor 112 may be configured to receive a processed substrate 150 from a printing nest 131 coupled to the rotary actuator assembly 130 and transfer the substrate 150 to the drying chamber 200. The input conveyor 113 and the drier conveyor 114, which is contained in the drying chamber 200, may be automated substrate handling devices that are part of a larger production line. For example, the input conveyor 113 and the exit conveyor 114 may be part of the SoftlineTM tool available from Baccini S.p.A. of Treviso, Italy, of which the system 100 may be a module. [0027] While the drier conveyor 114, the incoming conveyors 111, the outgoing conveyors 112, and the input conveyors 113 are generally described below as a belt type conveyor, other types of conveyors, robotic devices, or other similar substrate transferring mechanisms could be used without varying from the basic scope of the invention described herein. One will note that Figures IA- IB are only intended to illustrate one possible processing system configuration that could benefit from the various embodiments described herein, and thus other conveyor configurations and other types of material deposition chambers could be used without deviating from the basic scope of the invention described herein. [0028] As shown in Figure IA, the rotary actuator assembly 130 may be rotated and angularly positioned about the "B" axis by a rotary actuator (not shown) and a system controller 101, such that the printing nests 131 may be selectively angularly positioned within the system 100. The rotary actuator assembly 130 may also have one or more supporting components to facilitate the control of the print nests 131 or other automated devices used to perform a substrate processing sequence in the system 100.

[0029] In one embodiment, the rotary actuator assembly 130 includes four printing nests 131, or substrate supports, that are each adapted to support a substrate 150 during the screen printing process performed within the screen printing chamber 102. Figure IB schematically illustrates the position of the rotary actuator assembly 130 in which one printing nest 131 is in position "1" to receive a substrate 150 from the input conveyor 113, another printing nest 131 is in position "2" within the screen printing chamber 102 so that another substrate 150 can receive a screen printed pattern on a surface thereof, another printing nest 131 is in position "3" for transferring a processed substrate 150 to the output conveyor 112, and another printing nest 131 is in position "4", which is an intermediate stage between position "1" and position "3".

[0030] In one embodiment, the screen printing chamber 102 in system 100 uses a conventional screen printing device available from Baccini S.p.A., which is adapted to deposit material in a desired pattern on the surface of the substrate 150 positioned on the printing nest 131 in position "2" during the screen printing process. In one embodiment, the screen printing chamber 102 contains a plurality of actuators, for example, actuators 102A (e.g., stepper motors, servomotors) that are in communication with the system controller 101 and are used to adjust the position and/or angular orientation of the screen printing device with respect to the substrate via commands sent from the system controller 101. In one embodiment, the screen printing chamber 102 is adapted to deposit a metal containing or dielectric containing material on the solar cell substrate 150. In one embodiment, the solar cell substrate 150 has a width between about 125 mm and about 156 mm and a length between about 70 mm and about 156 mm. [0031] In one embodiment, the system 100 includes an inspection assembly 200 adapted to inspect a substrate 150 located on the printing nest 131 in position "1". The inspection assembly 200 may include one or more cameras 121 positioned to inspect an incoming, or processed substrate 150, located on the printing nest 131 in position "1". In one embodiment, the inspection assembly 200 includes at least one camera 121 (e.g., CCD camera) and other electronic components capable of inspecting and communicating the inspection results to the system controller 101 used to analyze the orientation and position of the substrate 150 on the printing nest 131.

[0032] The system controller 101 facilitates the control and automation of the overall system 100 and may include a central processing unit (CPU) (not shown), memory (not shown), and support circuits (or I/O) (not shown). The CPU may be one of any form of computer processors that are used in industrial settings for controlling various chamber processes and hardware (e.g., conveyors, detectors, motors, fluid delivery hardware, etc.) and monitor the system and chamber processes (e.g., substrate position, process time, detector signal, etc.). The memory is connected to the CPU, and may be one or more of a readily available memory, such as random access memory (RAM), read only memory (ROM), floppy disk, hard disk, or any other form of digital storage, local or remote. Software instructions and data can be coded and stored within the memory for instructing the CPU. The support circuits are also connected to the CPU for supporting the processor in a conventional manner. The support circuits may include cache, power supplies, clock circuits, input/output circuitry, subsystems, and the like. A program (or computer instructions) readable by the system controller 101 determines which tasks are performable on a substrate. Preferably, the program is software readable by the system controller 101, which includes code to generate and store at least substrate positional information, the sequence of movement of the various controlled components, substrate inspection system information, and any combination thereof. In one embodiment of the present invention, the system controller 101 includes software to actuate the non-contact substrate handling device for moving the substrate as necessary, such as pre- centering the substrate, as the substrate travels through processing system 100. [0033] Figures IA- IB generally illustrate a system configuration that contains a drying chamber 200 that is positioned to receive a substrate 150 from an outgoing conveyor 112, after the substrate 150 has been processed in a screen printing chamber 102. In general, the drying chamber 200 contains a processing region 202 in which energy is delivered from a thermal system 201 to one or more substrates positioned therein, so that the material deposited on a surface of the one or more substrates can be dried. In one example, the deposited material is an aluminum (Al) containing paste, such as a lead free aluminum cermet paste (e.g., Al Cermet 6214) that is commonly used in solar cell production processes to form the backside contacts on a crystalline solar cell substrate. The processing region 202 has a drier conveyor 114 that is adapted to receive a substrate from another transferring device (e.g., outgoing conveyor 112), and move and/or position the substrate 150 within the processing region 202. [0034] After drying of the substrates another system 100 may be placed in-line to process the second side of the substrate 150. A flipping device or unit (not shown) is positioned to receive and transfer substrates from automatic production system conveyors such as conveyors 113 and 114, which are used to transfer substrates between various processing stages. A pre-centering unit, such as units 170 or 160 employing the non-contact handling device as above may also be placed in the production line between the drier 200 and a flipping unit (not shown) to pre-center the substrate 150 to properly align the substrate with the flipping unit. Additionally, embodiments of the invention may include other units besides pre-centering units that are used to pick and place substrates along the production process or move them in any manner as necessary.

[0035] Figure 2A is a plan view of a front surface 155, or light receiving surface, of a solar cell substrate 150. Solar cell substrates may be 300 microns thick but are becoming increasingly thinner such as between 100-150 microns thick. As the solar cell substrates become thinner, greater care must be taken when handling the substrates during their manufacture so as not to chip, break, crack, or otherwise mar the substrate, particularly when the solar cell has been partially processed to form some features of a photovoltaic cell. For example, solar cells are regularly repositioned and centered during their manufacture to properly deposit the various layers that from the photovoltaic cell and enable current production. With increased handling, the likelihood of damaging substrates increases. Some examples of photovoltaic cell manufacture and handling issues are discussed in more detail below. [0036] Electrical current generated by the junction formed in a solar cell when illuminated flows through a front contact structure 156 disposed on the front surface 155 of the solar cell substrate 150 and a back contact structure (not shown) disposed on the back surface (not shown) of the solar cell substrate 150. The front contact structure 156, as shown in Figure 2A, may be configured as widely-spaced thin metal lines, or fingers 152, that supply current to larger bus bars 151. Typically, the front surface 155 is coated with a thin layer of dielectric material, such as silicon nitride (SiN), which acts as an antireflection coating (ARC) to minimize light reflection. The back contact structure (not shown) is generally not constrained to thin metal lines since the back surface of the solar cell substrate 150 is not a light receiving surface.

[0037] In one embodiment, the placement of the buss bars 151 and the fingers 152 on the front surface 155 of the substrate 150 depends on the alignment of a screen printing device used in the screen printing chamber 102 (Figure IA) with respect to the positioning of the substrate 150 on the printing nest 131. The screen printing device is generally a sheet or plate contained in the screen printing chamber 102. The sheet or plate has a plurality of holes, slots, or other features formed therein to define the pattern and placement of screen printed ink or paste on the front surface 155 of the substrate 150. Typically, the alignment of the screen printed pattern of fingers 152 and buss bars 151 on the surface of the substrate 150 is dependent on the alignment of the screen printing device to an edge of the substrate 150. For instance, the placement of a single layer screen printed pattern of buss bars 151 and fingers 152 may have an expected position X and an expected angle orientation R with respect to an edge 150A and an expected position Y with respect to an edge 150B of the substrate 150 as shown in Figure 2 A. The positional error of the single layer of the screen printed pattern of fingers 152 and buss bars 151 on the front surface 155 of the substrate 150 from the expected position (X, Y) and the expected angular orientation R on the front surface 155 of the substrate 150 may be described as a positional offset (ΔX, ΔY) and an angular offset ΔR. Thus, the positional offset (ΔX, ΔY) is the error in the placement of the pattern of buss bars 151 and fingers 152 relative to the edges 150A and 150B, and the angular offset ΔR is the error in the angular alignment of the printed pattern of buss bars 151 and fingers 152 relative to the edge 150B of the substrate 150. The misplacement of a single layer of the screen printed pattern of buss bars 151 and fingers 152 on the front surface 155 of the substrate 150 can affect the ability of the formed device to perform correctly and thus affect the device yield of the system 100. However, minimizing positional errors becomes even more critical in applications having multiple layers of the screen printing pattern printed atop one another.

[0038] In an effort to increase the current carrying capacity of the front contact structure 156 without reducing the efficiency of a completed solar cell, the height of the buss bars 151 and fingers 152 may be increased without increasing their thickness by screen printing the pattern of buss bars 151 and fingers 152 in two or more successive layers. Figure 2B is a schematic side cross-sectional view of a portion of the substrate 150 having a properly aligned second layer of buss bars 15 IB and fingers 152B printed atop a first layer of buss bars 15 IA and fingers 152A. [0039] Figure 2C is a schematic isometric view of the solar cell substrate 150 illustrating misalignment of screen printing layers. Typically, the alignment of the screen printed pattern for the second layer onto the first layer is dependent on the alignment of the screen printing device with respect to edges 150A, 150B of the substrate 150 as shown in Figure 2A. However, misalignment of the second layer with respect to the first layer may occur due to a change in the positioning of the substrate 150 and/or the compounded effect of the measurement tolerances between the first screen printing operation and successive screen printing operations. In general, the misalignment of the second layer of fingers 152B and buss bars 15 IB with respect to the first layer of fingers 152A and buss bars 15 IA can be described as a positional misalignment (Xl, Yl) and an angular misalignment Rl . The positional and angular misalignment of the second layer of the screen printing pattern with respect to the first layer of the screen printed pattern may reduce the device performance and the device efficiency due to covering or shadowing more of the front surface 155 than would a single layer pattern, resulting in an overall reduction in the device yield of the system 100. [0040] In an effort to improve the handling of substrates during solar cell manufacture, embodiments of the invention utilize a non- contact substrate handling device as illustrated in Figures 3 and 4. The embodiments of the invention may be used as part of the pre-centering units discussed above. Indeed, embodiments of the invention not only include such processing units, but also include any handling unit necessary to move a substrate. Moreover, embodiments of the invention may include end effectors used for handling substrates during processing. [0041] Figures 3 and 4 show a schematic isometric view of the front side (Figure 3) or back side (Figure 4) of a non-contact substrate handling device 300 according to one embodiment of the present invention. The device 300 includes a body 310 having a substrate receiving surface 312 surrounding a gas injection port 314 and a gas exhaust port 316. A gas source 318 is connected to the gas injection port 314 to provide gas for actuating the non-contact substrate handling device. The gas exhaust port 316 is one or more passages 320 positioned near the substrate receiving surface 312. The gas injection port 314 is one or more passages 322 positioned away from the substrate receiving surface 312. For example, the gas injection port 314, including one or more passages 322, may be centrally located along the body 310 as shown in Figures 3 and 4.

[0042] In one embodiment of the invention, the gas injection port 314 and the gas exhaust port 316 form a Venturi flow device i.e. a flow device for generating a vacuum by means of air flow or purge-gas flow through a restricted orifice. In another embodiment of the invention, the gas injection port 314 and the gas exhaust port 316 form a Bernoulli flow device or gripper 330. The substrate receiving surface 312 may be an annular disc surrounding a central depression 306 in the body 310. For example, the annular disc may comprise a detachable ring 334 secured to the body 310, such as by screws 340. The body may generally form other non-circular shapes such as an oval, rectangle, or other polygonal shapes. In those embodiments, a closed banded shape corresponding to the perimeter of the body face may also surround and be secured to the body to form the substrate receiving surface 312. [0043] In one embodiment of the invention, the body 310 of the non-contact handling device 300 may comprise a Bernoulli gripper 330 secured within a housing 338 having one or more supporting members 344. The housing 338 has an annular face 332 that extends the surface area of the Bernoulli gripper 330. In this embodiment, the housing 338 is secured to a detachable ring 334 at one or more supporting members 344, such as by screws 340. The detachable ring 334 has a substrate receiving surface 312. A gasket 336 may be disposed on the substrate receiving surface 312 to dampen contact made with the substrate 150 during handling and to provide a sealing area. The exhaust passages 320 of exhaust port 316 may be contoured. The gas exhaust port may be two or more passages such as the three passages 320 shown in Figures 3 and 4.

[0044] The non-contact handling device 300 may be made from material comprising plastic, carbon, metal, aluminum or combinations thereof. For example portions of body 310 may comprise aluminum and plastic and a detachable ring 330 secured to the body 310 may comprise plastic and rubber. Thus, the substrate receiving surface forms a continuous contacting area that touches the substrate to provide better support and balance. Moreover, less gas pressure is required to actuate the non-contact handling device 300 to more gently handle the fragile substrates 150. [0045] Figures 5A and 5B illustrate a schematic cross-sectional view of a substrate and one embodiment of the substrate handling device along line AA — AA of Figure 4. The figures show non-contact handling of the substrate before (Figure 5A) and during (Figure 5B) handling of the substrate 150. Gas passes from a gas source 318 to the gas injection port 314 injecting gas in to the area between the substrate and the non-contact handling device. The gas may pass around a restriction 342 of the injection port 314 that forms passages 322. Initially, the gas flows without restraint over the substrate and passes through an area in between the handling device and the substrate as generally indicated by arrows "A". [0046] As the gas flows over the substrate 150 and as the non-contact handling device 300 approaches the substrate, the pressure above the substrate decreases, resulting in a pressure imbalance. As the imbalance increases, the higher gas pressure below the substrate forces the substrate to lift, as indicated by arrows "C". A vacuum region 510 generally between the substrate and the body 310 is created above the substrate surface as also indicated by arrows "B". The gas subsequently flows across the substrate surface and through the gas exhaust passages 320 of the gas exhaust port 316 as indicated by arrows "A". The rubber gasket 336 prevents the substrate from spinning and stabilizes the substrate while moving the substrate to a new position. The gasket 332 may also seal a portion 520 surrounding the vacuum region 510.

[0047] In another embodiment of the invention, the non-contact handling device 300 may have a face 332 of the body 310 that slopes from a central region of the body towards the substrate receiving surface 312. When a substrate 150 contacts the handling device 300, a gap is formed between the substrate 150 and the body 310 of the handling device 300. A declining slope may form from a central region of the body, such as a central depression 306, to an outer edge of the substrate receiving surface 312. [0048] As the slope declines towards the outer edge of the substrate receiving surface 312, the gap between the substrate 150 and the body 310 will decrease. In other words, the gap between body 310 and substrate 150 may vary from center to edge which may help maintain gas flow speed. As the gas exits the gas injection port 314 and travels along the pathway indicated by arrows "A", the gas may decrease in density and lose velocity. However, be decreasing the gap between the body 310 and the substrate 150, the density as well as velocity will not decrease as rapidly, meaning even lower gas pressures may be necessary to lift the substrate 150.

[0049] Figure 6 is a schematic diagram of an operational sequence for non- contact handling of a substrate according to one embodiment of the present invention. The method 600 of non-contact handling a substrate includes placing a handling device over the substrate, box 602. The handling device includes a body having a substrate receiving surface surrounding a gas injection port and a gas exhaust port, box 604. A gas source is connected to the gas injection port and the gas exhaust port is one or more passages positioned near the substrate receiving surface, and the gas injection port is one or more passages positioned away from the substrate receiving surface, box 606. The method also includes creating a vacuum region above the substrate by flowing gas out of the gas injection port, over the substrate, towards the substrate receiving surface, and through the gas exhaust port, box 608. A portion surrounding the vacuum region is sealed by causing the substrate to contact the substrate receiving surface, box 610, and moving the substrate 150, box 612.

[0050] Although embodiments of the present invention are depicted in Figures IA and IB with respect to a system 100 having a single input and single output, embodiments of the invention are equally applicable to a system 700 having dual inputs and dual outputs as depicted in Figure 7.

[0051] Figure 7 is a top plan view of a system 700 that may be used in conjunction with embodiments of the present invention to form multiple layers of a desired pattern, such as buss bars 151 and fingers 152, on the front surface 150 of the substrate 150. As shown, the system 700 differs from the system 100 depicted in Figures IA and IB in that the system 700 includes two input conveyors 111, two non-contact substrate handling units 175 on centering conveyors 170 used to pre-center substrates, two pre-centering units 160, and two output conveyors 112. The system 700 also differs from the system 100 in that the system 700 includes two screen printing chambers 102. The system also includes to drier conveyors 114 with two driers 200. However, the operating sequence of embodiments of the invention with respect to the system 700 is substantially the same as with respect to the system 100. For instance, the operating sequence 600 with respect to the first substrate 150 initially loaded into position "1" is the same as previously described with respect to Figure 6. However, the operating sequence 600 may run simultaneously with the second substrate 150 initially loaded into position "3". [0052] Embodiments of the present invention may provide various advantages during the handling of substrates. Continuous surface contact by the substrate handling device instead of point contact may reduce vibration and induce less mechanical stress within the substrate. The actual area for gas flow is increased resulting in lower pressures necessary to producing the lifting effect of the non- contact handling device. Additionally, less dust may contaminate the circuits formed on the substrate compared to vacuum handling system which will eventually fill with dust, creating a large source of dust within the chamber. Moreover, in vacuum handling systems, particles may clog the vacuum system, whereas in embodiments of the present invention because no gas is pulled into the handling system, no clogging occurs. Another possible advantage is that when embodiments of the invention are used to handle substrates after passing through a heated drier, the substrates will be simultaneously cooled while being handled.

[0053] While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.

Claims

1. A non-contact substrate handling device, comprising a body having a substrate receiving surface surrounding a gas injection port and a gas exhaust port; and a gas source connected to the gas injection port, wherein the gas exhaust port is one or more passages positioned near the substrate receiving surface, and the gas injection port is one or more passages positioned away from the substrate receiving surface.

2. The non-contact handling device of claim 1, wherein the gas injection port and the gas exhaust port form a Venturi flow device.

3. The non-contact handling device of claim 1, wherein the gas injection port and the gas exhaust port form a Bernoulli gripper.

4. The non-contact handling device of claim 1, wherein the substrate receiving surface is an annular disc surrounding a central depression in the body.

5. The non-contact handling device of claim 1, wherein the substrate receiving surface comprises a detachable ring secured to the body.

6. The non-contact handling device of claim 1, wherein the substrate receiving surface comprises a gasket.

7. The non-contact handling device of claim 1, wherein each exhaust passage is contoured.

8. The non-contact handling device of claim 1, wherein the gas exhaust port is two passages.

9. The non-contact handling device of claim 1, wherein the gas exhaust port is three passages.

10. The non-contact handling device of claim 1, wherein the body is made from material comprising plastic, carbon, metal, aluminum, rubber, or combinations thereof.

11. The non-contact handling device of claim 1, wherein a gap distance formed between the body and the substrate when the substrate contacts the handling device, varies from a central region of the body towards an outer edge of the substrate receiving surface.

12. The non-contact handling device of claim 11, wherein the gap distance decreases from the central region of the body towards the outer edge of the substrate receiving surface.

13. A method of non-contact handling a substrate, comprising: placing a handling device over the substrate, the handling device comprising: a body having a substrate receiving surface surrounding a gas injection port and a gas exhaust port; a gas source connected to the gas injection port, wherein the gas exhaust port is two or more passages positioned near the substrate receiving surface, and the gas injection port is one or more passages positioned away from the substrate receiving surface; creating a vacuum region above the substrate by flowing gas out of the gas injection port, over the substrate, towards the substrate receiving surface, and through the gas exhaust port; sealing a portion surrounding the vacuum region by causing the substrate to contact the substrate receiving surface; and, moving the substrate.

14. The method of claim 13, further comprising cooling the substrate while moving the substrate.

15. The method of claim 13, further comprising centering the substrate on a transport system while moving the substrate.

16. The method of claim 13, wherein the substrate receiving surface is an annular disc surrounding a central depression in the body.

17. The method of claim 13, wherein the substrate receiving surface comprises a gasket.

18. A screen printing system, comprising: a rotary actuator having a printing nest disposed thereon and movable between a first position, a second position, and a third position; an input conveyor positioned to load a substrate onto the printing nest in the first position; a pre-centering unit having a substrate handling device positioned to center a substrate on the input conveyor, the substrate handling device comprising: a body having a substrate receiving surface surrounding a gas injection port and a gas exhaust port; and a gas source connected to the gas injection port, wherein the gas exhaust port is one or more passages positioned near the substrate receiving surface, and the gas injection port is one or more passages positioned away from the substrate receiving surface; a screen printing chamber having an adjustable screen printing device disposed therein, the screen printing chamber positioned to print a pattern onto the substrate when the printing nest is in the second position, wherein the pattern comprises a conductive structure of thin lines; an exit conveyor positioned to unload the substrate when the printing nest is in the third position; and a system controller comprising software configured to actuate the substrate handling device for moving the substrate and for centering the substrate on the input conveyor.

19. The screen printing system of claim 18, further comprising: a drier conveyor positioned to receive substrates from the exit conveyor and adapted to transfer one or more substrates through a drier unit; and a substrate handling unit positioned to handle the substrates after passing through the drier unit, the substrate handling unit having a substrate handling device positioned to center a substrate on the input conveyor, the substrate handling device comprising: a body having a substrate receiving surface surrounding a gas injection port and a gas exhaust port; and a gas source connected to the gas injection port, wherein the gas exhaust port is one or more passages positioned near the substrate receiving surface, and the gas injection port is one or more passages positioned away from the substrate receiving surface.

20. A screen printing system, comprising: a rotary actuator having a printing nest disposed thereon and movable between a first position, a second position, and a third position; an input conveyor positioned to load a substrate onto the printing nest in the first position; a centering conveyor positioned to load a substrate on the input conveyor, the centering conveyor having a substrate handling device to center a substrate on the centering conveyor, the substrate handling device comprising: a body having a substrate receiving surface surrounding a gas injection port and a gas exhaust port; and a gas source connected to the gas injection port, wherein the gas exhaust port is one or more passages positioned near the substrate receiving surface, and the gas injection port is one or more passages positioned away from the substrate receiving surface;

a screen printing chamber having an adjustable screen printing device disposed therein, the screen printing chamber positioned to print a pattern onto the substrate when the printing nest is in the second position, wherein the pattern comprises a conductive structure of thin lines; an exit conveyor positioned to unload the substrate when the printing nest is in the third position; and a system controller comprising software configured to actuate the non-contact substrate handling device for moving the substrate and for centering the substrate on the input conveyor.