1. Field of the Invention
Embodiments of the present invention generally relate to an apparatus and method for moving, aligning, and processing a substrate. In particular, embodiments of the present invention may be used to accurately deposit a patterned layer on a substrate.
2. Description of the Related Art
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.
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 solar cells by improving device yield and increasing substrate throughput in a solar cell fabrication process.
Screen and ink jet printing have been used in printing designs on objects, such as cloth or ceramics, and are used in the electronics industry for printing electrical component patterns, such as electrical contacts or interconnects on a surface of a substrate. State of the art solar cell fabrication processes also use screen and ink jet printing processes. In these processes, the production throughput is limited by the amount of time used in moving and printing a pattern on a single substrate. One method of increasing throughput is by printing a pattern on more than one substrate at a time via a single print head. However, current methods fail to provide consistent pattern alignment on each individual substrate, which can lead to poor device performance and low device efficiency.
Therefore, there is a need for an apparatus for the production of solar cells, electronic circuits, or other useful devices that has an improved method of controlling the movement and alignment of substrates within a substrate processing system.
In one embodiment of the present invention, an apparatus for processing a substrate comprises, a planar stator, a first mover positioned on the planar stator, a second mover positioned on the planar stator, a first substrate support coupled to the first mover and positionable to receive a substrate in a substrate loading position, a second substrate support coupled to the second mover and positionable to receive a substrate in the substrate loading position, and a processing head configured to process a substrate positioned on the first substrate support when the first substrate support is in a first substrate processing position. In one embodiment, the first and second movers are configured to move laterally and longitudinally over the planar stator in a horizontal plane independently of one another. In one embodiment, the processing head is further configured to process a substrate positioned on the second substrate support when the second substrate support is in a second substrate processing position.
In another embodiment of the present invention, an apparatus for processing a substrate comprises a planar stator, a first mover positioned on the planar stator, a second mover positioned on the planar stator, a first substrate support coupled to the first mover and positioned to receive a substrate in a first substrate loading position, a second substrate support coupled to the second mover and positioned to receive a substrate in a second substrate loading position, a first processing head configured to process a substrate positioned on the first substrate support when the first substrate support is in a first substrate processing position, and a second processing head configured process a substrate positioned on the second substrate support when the second substrate support is in a second substrate processing position. In one embodiment, the first and second movers are configured to move laterally and longitudinally over the planar stator in a horizontal plane independently of one another.
In yet another embodiment, a method for processing a substrate comprises orienting a first substrate support in a first substrate loading position via a planar stator and a first mover attached to the first substrate support, orienting a second substrate support in a second substrate loading position via the planar stator and a second mover attached to the second substrate support, receiving a first substrate on the first substrate support, capturing data via a first inspection system regarding the position and orientation of the first substrate on the first substrate support, receiving a second substrate on the second substrate support, capturing data via a second inspection system regarding the position and orientation of the second substrate on the second substrate support, moving the first substrate support from the first substrate loading position to a first substrate processing position at least partially based on the data captured by the first inspection system via the planar stator and the first mover, processing the first substrate via a first processing head, moving the second substrate support from the second substrate loading position to a second substrate processing position at least partially based on the data captured by the first inspection system via the planar stator and the second mover, and processing the second substrate via a second processing head.
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.
Embodiments of the present invention provide an apparatus and method for processing substrates in a processing system that has an increased system throughput, improved system uptime, and improved device yield performance, while maintaining a repeatable and accurate substrate processing. In one embodiment, the processing system is adapted to perform a screen or ink jet printing process within a portion of a crystalline silicon solar cell production line in which a substrate is patterned with a desired material, 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 Softline™ tool available from Baccini S.p.A., which is owned by Applied Materials, Inc. of Santa Clara, Calif. In another embodiment, the processing system is adapted to perform material removal processes, such as laser ablation or etching one or more regions of a substrate. In other embodiments, the processing system may be adapted to perform other material removal, deposition, thermal, and/or device testing processes.
In one embodiment, substrates 150 are microcrystalline silicon substrates used for processing solar cells thereon. In another embodiment, substrates 150 are green tape ceramic substrates or the like.
In one embodiment of the present invention, the system 100 is a screen printing processing system and the processing heads 102 include screen printing components, which are configured to screen print a patterned layer of material on a substrate 150. In another embodiment, the system 100 is an ink jet printing system and the processing heads 102 include ink jet printing components, which are configured to deposit a patterned layer of material on a substrate 150. In yet another embodiment, the system 100 is a processing system that includes material removal components in the processing head 102, such as a laser for ablating or etching one or more regions of a substrate 150. In other embodiments, the system 100 may comprise other substrate processing modules requiring precise movement and positioning of the substrates for processing.
In one embodiment, the incoming conveyor 111 and outgoing conveyor 112 include at least one belt 116 to support and transport the substrates 150 to a desired position within the system 100 by use of an actuator (not shown) that is in communication with the system controller 101. While
In one embodiment, the system 100 also includes an inspection system 200, which is adapted to locate and inspect the substrates 150 before and after processing has been performed. The inspection system 200 may include one or more cameras 120 that are positioned to inspect a substrate 150 positioned in the loading/unloading positions “1” and “3,” as shown in
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, the two processing heads 102 utilized in the system 100 may be conventional screen printing heads available from Baccini S.p.A, which are adapted to deposit material in a desired pattern on the surface of a substrate 150 disposed on a processing nest 131 in position “2” or “4” during a screen printing process. In one embodiment, the processing head 102 includes a plurality of actuators, for example, actuators 105 (e.g., stepper motors or servomotors) that are in communication with the system controller 101 and are used to adjust the position and/or angular orientation of a screen printing mask (not shown) disposed within the processing head 102 with respect to the substrate 150 being printed. In one embodiment, the screen printing mask is a metal sheet or plate with a plurality of holes, slots, or other apertures formed therethrough to define a pattern and placement of screen printed material on a surface of a substrate 150. In one embodiment, the screen printed material may comprise a conductive ink or paste, a dielectric ink or paste, a dopant gel, an etch gel, one or more mask materials, or other conductive or dielectric materials. In general, the screen printed pattern that is to be deposited on the surface of a substrate 150 is aligned to the substrate 150 in an automated fashion by orienting the screen printing mask using the actuators 105 and information received by the system controller 101 from the inspection system 200. In one embodiment, the processing heads 102 are adapted to deposit a metal containing or dielectric containing material on a solar cell substrate having a width between about 125 mm and 156 mm and a length between about 70 mm and 156 mm.
In order to transfer the mover 144 in the X-Y direction on the plane of the stator 142 by virtue of the thrust generated between the permanent magnet part 143 and the armature coil part 145, the mover 144 may be raised a predetermined height from the plane surface of the stator 142 via one or more air nozzles (not shown) provided in the lower surface of the mover 144. Thus, when the mover 144 receives an electric signal via the cables 149, air may also be delivered through the nozzles via tubing coupled to an air source and disposed in the cables 149. The delivery of air through the nozzles allows near frictionless X-Y movement and precise X-Y positioning of the mover 144 on the stator 142.
In one embodiment of the present invention, each mover 144 has a respective processing nest 131 coupled thereto. In such an embodiment, the actuator assembly 140 is capable of precise X-Y movement and positioning of each processing nest 131 via signals sent through cables 149 from the system controller 101. In one embodiment, the actuator assembly 140 allows significant improvement in accuracy and repeatability over prior art substrate processing positioning systems.
In one embodiment, each of the processing nests 131 is affixed to a rotary actuator 148, which is positioned between and coupled to the processing nest 131 and its respective mover 144. The rotary actuator 148 may include a rotary plate attached to a stepper motor, servo motor, or other rotary mechanism in communication with the system controller 101 for precisely positioning each of the processing nests 131 at an angle with respect to the respective mover 144.
In another embodiment, the conveyor 139 is configured as a continuous conveyor system comprising one or more feed rollers 133 and one or more idler rollers 134 for feeding the material 137 positioned across the platen 138 as shown in
In certain embodiments of the present invention, the processing nests 131 are always configured in the same orientation when loading and unloading substrates 150. In such embodiments, the continuous conveyor configuration (
In a substrate transferring operation 602, a first pair of substrates 150 is transferred along the paths “A1” from the input conveyors 113 to the incoming conveyors 111. In this configuration the system controller 101 is used to coordinate the motion of the belts 116 and drive actuators (not shown) in each input conveyor 113 and incoming conveyor 111 so that the substrates 150 are reliably transferred between these automated components.
Next, in a substrate loading operation 604, each of the incoming conveyors 111 load the first pair of substrates 150 onto the processing nests 131 located in loading/unloading positions “1” and “3” as shown in
In an inspection operation 606, each of the first pair of substrates 150 may be inspected by the inspection system 200 to assure that there are no broken, chipped, or cracked substrates 150 positioned on the processing nests 131. Additionally, each inspection system 200 may capture images of the substrate 150 positioned on the processing nest 131 and send the images to the system controller 101 for analysis to determine the exact position and orientation of each substrate 150 on the respective processing nest 131. The location and orientation data of each substrate 150 on each processing nest 131 is subsequently used by the system controller 101 in conjunction with the respective processing head 102 and/or mover 144 for precise positioning of the substrate 150 during a processing operation as subsequently described.
Next, in a first processing nest moving operation 608, the processing nests 131 with the unprocessed substrates 150 disposed thereon are each moved inwardly from their respective loading positions “1” and “3” along path “A3” as shown in
In a second processing nest moving operation 610, all four processing nests 131 are substantially simultaneously moved along the paths “A4” via their respective movers 144 of the actuator assembly 140 as shown in
In a third processing nest moving operation 612, the processing nests 131 positioned inwardly from the respective loading/unloading positions “1” and “3” are moved outwardly along paths “A5” into the loading/unloading positions “1” and “3” via their respective movers 144 of the actuator assembly 140 as shown in
Concurrently, in an alignment operation 614, the substrates 150 located on the processing nests 131 positioned in the processing positions “2” and “4” shown in
In the embodiment, wherein the system 100 is a screen printing system, the location and orientation data may be used to position and orient the screen print components of the processing head 102 to improve the accuracy of the screen printing process. In one embodiment, the position of a printing mask contained in each of the processing heads 102 is automatically adjusted in both the X-Y directions and the angular orientation to align the printing mask of the processing head 102 to a desired position over the substrate 150 positioned on the processing nest 131 based on the data received during the inspection step 606. In another embodiment, the location and orientation data collected by the inspection system 200 for each substrate 150 on each processing nest 131 is used by the system controller 101 to precisely position each processing nest 131 relative to the printing mask in each processing head 102 in the X-Y directions via the respective mover 144 and to angularly adjust the orientation of the print mask in the processing head 102 to a desired position and orientation relative to the substrate 150 positioned on the processing nest 131 using one or more of the actuators 105.
In one embodiment, the location and orientation data collected by the inspection system 200 for each substrate 150 on each processing nest 131 is used by the system controller 101 to precisely position each processing nest 131 in the X-Y directions via the respective mover 144 and to angularly adjust the orientation of the processing head 102 to a desired orientation relative to the substrate 150 positioned on the processing nest 131. For instance, as shown in
In another embodiment, the location and orientation data for each substrate 150 disposed on each processing nest 131 is collected and used by the system controller 101 to precisely position each processing nest 131 under each processing head 102 in the X-Y directions via the respective mover 144 and to angularly align the substrate 150 disposed on each processing nest 131 to the processing head 102 using the respective rotary actuator 148 coupled to the processing nest 131 and the mover 144. In this configuration, all adjustment for the position and orientation of the substrate 150 is compensated for by each processing nest 131, thereby allowing processing of multiple substrates 150 (each configured on an individual processing nest 131) in a single processing operation by a single screen processing head 102, as subsequently described below.
In a processing operation 616, a process, such as screen printing, ink jet printing, laser ablation, or the like, is performed on the first pair of substrates 150 precisely positioned in processing positions “2” and “4” as shown in
In a fourth processing nest moving operation 618, each of the processing nests 131, located in the processing positions “2” and “4” and supporting a processed substrate 150, is moved along the path “A4” via its respective mover 144 of the actuator assembly 140 as shown in
In an alternate fourth processing nest moving operation 618, each of the processing nests 131, located in the processing positions “2” and “4” and supporting a processed substrate 150, is moved back along the path “A6” to its previous location inboard of its respective loading/unloading position “1” or “3” via its respective mover 144 of the actuator assembly 140 as shown in
In a fifth processing nest moving operation 620, the processing nests 131 supporting the processed substrates 150 and located inwardly from the loading/unloading positions “1” and “3” are moved outwardly along paths “A5” via their respective mover 144 of the actuator assembly 140 as shown in
In an unloading operation 622, each of the first pair of processed substrates 150 supported by the processing nests 131 located in the loading/unloading positions “1” and “3” is unloaded onto the respective outgoing conveyor 112 as shown in
Finally, in a substrate transferring operation 624, the first pair of processed substrates 150 is transferred along the paths “A8” from the outgoing conveyors 112 to the output conveyors 114 as shown in
In steady state operation, the operations 602-624 of the operating sequence 600 are continually repeated for continuous processing of substrates 150 in a production line environment. The number and sequence of operations illustrated in
In addition to the above described movement of each substrate 150 between the loading/unloading positions “1” and “3” and the processing positions “2” and “4”, a number of other alternative transfer paths are embodied within the scope of the present invention. In one embodiment, the processing nests 131 that are initially located in positions “1” and “2” continually exchange positions in the loading, processing, and unloading operations. Concurrently, the processing nests 131 that are initially located in positions “3” and “4” continually exchange positions in the loading, processing, and unloading operations.
In another embodiment, the processing nest 131 that is initially located in the loading/unloading position “1,” moves to printing position “2” and then back to the loading/unloading position “1.” Concurrently, the processing nest 131 that is initially located in the loading/unloading position “3,” moves to processing position “4” and then back to the loading/unloading position “3.” These movements are continually repeated throughout the processing sequence.
In yet another embodiment, the printing nest 131 that is initially located in the loading/unloading position “1,” moves to processing position “2” and then moves to the loading/unloading position “3” as previously described. The processing nest 131 then moves back to processing position “2” and then moves back to the loading/unloading position “1”. Concurrently, the processing nest 131 that is initially located in the loading/unloading position “3,” moves to processing position “4” and then moves to the loading/unloading position “1.” The processing nest 131 then moves back to processing position “4” and then moves back to the loading/unloading position “3.” These movements are continually repeated throughout the processing sequence.
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.
Number | Date | Country | Kind |
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UD2009A000129 | Jul 2009 | IT | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/EP09/62845 | 10/2/2009 | WO | 00 | 1/20/2012 |