Substrate transport method and substrate processing system

Abstract

To provide a technique that can easily and accurately estimate substrate warpage.SOLUTION: A substrate transfer method comprises the processes of: (A) carrying a substrate into a positioning module by holding the substrate by a transfer robot and placing the substrate on a stage of the positioning module based on the passage of the transfer robot through the stage of the positioning module; (B) measuring an eccentricity of the substrate by the positioning module and estimating a warpage amount of the substrate based on the measured eccentricity amount of the substrate; and (C) carrying the substrate removed from the positioning module into another module based on the estimated warpage amount of the substrate, in this order. In the process (A), the substrate is moved diagonally downward relative to the stage of the positioning module.SELECTED DRAWING: Figure 1

Description

Technical Field

[0006] , , , ,

[0001] The present disclosure relates to a substrate transfer method and a substrate processing system.

Background Art

[0002] A substrate processing system transfers a substrate from an atmospheric transfer module to a vacuum transfer module and processes the substrate in one or more processing modules connected to the vacuum transfer module. The atmospheric transfer module is provided with an alignment module (alignment device) that measures the amount of eccentricity of the substrate before processing and aligns the position of the substrate.

[0003] By the way, the substrate processed by the substrate processing system may be warped in the plane. Patent Document 1 discloses a technique for obtaining a luminance distribution pattern in the radial direction of a substrate by an imaging unit and predicting the warping state of the substrate based on the relative lifting amount of the imaging unit and the substrate.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The present disclosure provides a technique for easily and accurately estimating the warp of a substrate.

Means for Solving the Problems

[0006] According to one aspect of the present disclosure, a substrate transport method is provided, which involves the steps of (A) holding the substrate with a transport robot and transporting the substrate into an alignment module, and placing the substrate on the stage of the alignment module based on the transport robot passing over the stage of the alignment module; (B) measuring the eccentricity of the substrate with the alignment module and estimating the amount of warping of the substrate based on the measured eccentricity of the substrate; and (C) transporting the substrate that has been transported out of the alignment module into another module based on the estimated amount of warping of the substrate, wherein in step (A), the substrate is moved diagonally downward relative to the stage of the alignment module. [Effects of the Invention]

[0007] According to one embodiment, the warping of the substrate can be estimated easily and accurately. [Brief explanation of the drawing]

[0008] [Figure 1] This is a plan view showing the configuration of the substrate processing system according to the first embodiment. [Figure 2] This is a magnified perspective view of the end effector of a transport robot. [Figure 3] This is a flowchart showing the processing flow for the substrate transport method. [Figure 4] This diagram shows the substrate placement operation in a positioning device. [Figure 5] This figure shows the placement operation of a substrate W with convex warping in a positioning device. [Figure 6] Figure 6(A) is a graph illustrating the results of measuring the position of the outer edge of a substrate without warping using an alignment device. Figure 6(B) is a graph illustrating the results of measuring the position of the outer edge of a substrate with convex warping using an alignment device. [Figure 7] This is a side view illustrating the principle of estimating the amount of warping from the eccentricity of the substrate. [Figure 8] This diagram shows the substrate mounting operation in a load lock module. [Figure 9] This figure shows the mounting operation of the end effector of the substrate processing system according to the second embodiment. [Figure 10] Figure 10(A) shows an example of placing a convex-curved substrate using the placement operation of the second embodiment. Figure 10(B) shows an example of placing a concave-curved substrate using the placement operation of the second embodiment. [Figure 11] This graph illustrates the results of measuring the position of the outer edge of a concave, warped substrate using an alignment device. [Figure 12] This is an explanatory diagram showing a modified substrate processing system. [Modes for carrying out the invention]

[0009] The following describes embodiments for implementing this disclosure with reference to the drawings. In each drawing, the same reference numerals are used for identical components, and redundant explanations may be omitted.

[0010] Figure 1 is a plan view showing the configuration of the substrate processing system 1 according to the first embodiment. For convenience, some internal components of the device are shown transparently in Figure 1. The substrate processing system 1 is a system that transports substrates W and performs various substrate processing on these substrates W. Examples of substrates W processed in the substrate processing system 1 include silicon wafers such as single-crystal silicon, silicon carbide, and SOI wafers, and compound semiconductor wafers such as GaAs wafers, SiC wafers, GaN wafers, and InP wafers.

[0011] The substrate processing system 1 comprises a plurality of processing modules 10, a vacuum transport module 20, an atmospheric transport module 30, and a plurality of load lock modules 40. The substrate processing system 1 also has a control device 90 that controls each module.

[0012] The plurality of processing modules 10 includes a processing vessel 11 that can be depressurized to a vacuum atmosphere, and a stage 12 on which a substrate W is placed inside the processing vessel 11. Each processing module 10 performs various substrate processes (etching, film formation, ashing, etc.) on the substrate W accommodated inside the processing vessel 11. Note that, in this specification, "vacuum" means a pressure lower than atmospheric pressure. The processing module 10 may be a plasma processing module that performs plasma processing on the substrate W. In FIG. 1, four processing modules 10 are shown, which are also referred to as processing modules 10A, 10B, 10C, and 10D in clockwise order from the side close to the load lock module 40. Each of the processing modules 10A, 10B, 10C, and 10D may perform the same type of substrate process, or may perform mutually different types of substrate processes. Of course, the number of processing modules 10 is not limited to this.

[0013] The vacuum transfer module 20 has a vacuum transfer container 21 in which a vacuum transfer robot 22 for transferring the substrate W is installed inside. A plurality of processing modules 10 and a plurality of load lock modules 40 are connected to the vacuum transfer container 21. The vacuum transfer module 20 depressurizes the inside of this vacuum transfer container 21 to a vacuum atmosphere, and transfers the substrate W between the processing module 10 and each load lock module 40, or between the plurality of processing modules 10 by the vacuum transfer robot 22. A gate valve 10G is provided between the vacuum transfer module 20 and each processing module 10.

[0014] The plurality of load lock modules 40 include a load lock container 41 into and out of which the substrate W can be carried. Each load lock module 40 is connected to the vacuum transfer module 20 via a gate valve 40G1, and is also connected to the atmospheric transfer module 30 via a gate valve 40G2. In FIG. 1, the substrate processing system 1 has three load lock modules 40 arranged side by side between the vacuum transfer module 20 and the atmospheric transfer module 30. Of course, the number of load lock modules 40 is not particularly limited either.

[0015] Each load lock container 41 has an internally adjustable pressure chamber that can be switched between a vacuum atmosphere and an atmospheric atmosphere. The internally adjustable pressure chamber is provided with a stage 42 on which a substrate W can be placed. When the load lock module 40 transports a substrate W from the atmospheric transport module 30 to the vacuum transport module 20, it maintains the internally adjustable pressure chamber at atmospheric pressure to receive the substrate W from the atmospheric transport module 30, and then reduces the pressure in the internally adjustable pressure chamber to transfer the substrate W to the vacuum transport module 20. When the load lock module 40 transports a substrate W from the vacuum transport module 20 to the atmospheric transport module 30, it maintains the internally adjustable pressure chamber in a vacuum to receive the substrate W from the vacuum transport module 20, and then increases the pressure in the internally adjustable pressure chamber to transfer the substrate W to the atmospheric transport module 30.

[0016] The atmospheric transport module 30 constitutes a substrate transport system for transporting substrates W in an atmospheric environment, relative to the vacuum transport module 20. The atmospheric transport module 30 has an atmospheric transport container 31 in which an atmospheric transport robot (hereinafter simply referred to as the transport robot 33) is installed. The atmospheric transport container 31 is formed in a rectangular shape in plan view. Multiple (three) load ports 32 and one alignment module (aligner module) 50 are connected to the atmospheric transport container 31. Each load port 32 is provided along the long side of the atmospheric transport container 31 opposite to the long side to which each load lock module 40 is connected. The alignment module 50 is provided on one of the short sides of the atmospheric transport container 31. The atmospheric transport module 30 may be, for example, an EFEM (Equipment Front End Module). The atmospheric transport module 30 may also have an FFU (Fan Filter Unit) that supplies clean air from the top of the atmospheric transport container 31, and an exhaust device that exhausts air.

[0017] A substrate storage case (substrate storage section) 39 such as a FOUP (Front Opening Unified Pod) capable of accommodating a plurality of substrates W is set in each of the plurality of load ports 32. An openable and closable gate 32G is provided between the atmospheric transport container 31 and each load port 32. In FIG. 1, three load ports 32 are installed, but of course, the number of load ports 32 is not particularly limited.

[0018] The transfer robot 33 transfers the substrate W in the atmospheric transport container 31. The transfer robot 33 has, for example, an end effector 34 that directly holds the substrate W, a plurality of arms 35 that support the position of the end effector 34 so as to be displaceable, and a base 36 that supports the arms 35. The transfer robot 33 may be configured to be reciprocally movable along the longitudinal direction of the atmospheric transport container 31 by a slide mechanism (not shown) provided on the base 36. Further, an elevating mechanism (not shown) that can integrally move the end effector 34 and the arms 35 along the vertical direction is provided on the base 36. The plurality of arms 35 rotate relative to each other about a joint portion connecting the respective arms 35 to move the end effector 34 of the transfer robot 33 to a predetermined horizontal position. The transfer robot 33 shown in FIG. 1 is configured to transfer the substrate W by one end effector 34, but the transfer robot 33 may be configured to transfer the substrate W by operating a plurality of end effectors 34 independently.

[0019] FIG. 2 is a perspective view showing an enlarged end effector 34 of the transfer robot 33. The end effector 34 has a base plate portion 341 and a pair (two) of fork plate portions 342. The base plate portion 341 and the pair of fork plate portions 342 are integrally formed with each other, and the upper and lower surfaces of each portion are continuously flat along the horizontal direction. The inner edges facing each other in the pair of fork plate portions 342 are continuous while curving through the arc-shaped edge at the tip of the base plate portion 341.

[0020] The base plate portion 341 is attached to the end arm 35 of the multiple arms 35. The pair of fork plate portions 342 extend in a substantially straight line from the base plate portion 341 toward the tip (opposite direction from the end arm 35). In addition, multiple (four) contact pads 343 that the circuit board W contacts are attached to the upper surface of the end effector 34.

[0021] The four contact pads 343 are provided one at each of the extended ends (tips) of each fork plate portion 342, and two at the center of the base plate portion 341 in the width direction. Hereinafter, the contact pads provided at the extended ends of each fork plate portion 342 will also be referred to as contact pads 343a, and the contact pads provided on the base plate portion 341 will also be referred to as contact pads 343b.

[0022] The upper surface of each contact pad 343 is composed of a low-profile section 343L and a high-profile section 343H, with a guide step at the boundary between the low-profile section 343L and the high-profile section 343H. Each contact pad 343 has a guide step, which is a mutually cooperating arc-shaped boundary, and this guide step can form a virtual circle with a diameter slightly larger than the outer diameter (diameter) of the substrate W. The end effector 34 supports the substrate inside the guide step by each contact pad 343. Specifically, the lower surface of the substrate W is in contact with the low-profile section 343L, while the boundary wall with the high-profile section 343H guides the outer edge of the substrate W.

[0023] Furthermore, the end effector 34 is equipped with a clamping mechanism 344 that clamps the substrate W between the contact pads 343 of each fork plate portion 342. The clamping mechanism 344 includes a reciprocating drive unit 345 attached to the end effector 34 (or arm 35), a frame body 346 that moves back and forth by the reciprocating drive unit 345, and a pair (two) rollers 347 fixed to the frame body 346. The reciprocating drive unit 345 has a drive source (not shown), such as a cylinder mechanism, and moves the frame body 346 back and forth under the drive of the drive source. The frame body 346 has a pair of vertical frames that extend parallel to the longitudinal direction of the end effector 34 (the extending direction of the pair of fork plate portions 342), and a horizontal frame that bridges the pair of vertical frames. The pair of rollers 347 are provided at the extended ends (one end) of the pair of vertical frames, respectively. The pair of rollers 347 are arranged to roll freely at the same height as the substrate W located on the low-profile portion 343L of each contact pad 343.

[0024] With the clamp mechanism 344 configured in this way, the frame body 346 is advanced by the forward / backward drive unit 345 while the substrate W is placed on each contact pad 343. When the pair of rollers 347 come into contact with the outer edge of the substrate W as the frame body 346 advances, the substrate W is pushed towards the front. The end effector 34 then clamps the outer edge of the substrate W between the guide steps provided on the contact pads 343a of the pair of fork plate portions 342 and the pair of rollers 347. As a result, the holding position of the substrate W is defined as the position in contact with the pair of contact pads 343a. The transport robot 33 can hold and stably transport the substrate W by keeping the holding form (attitude, position, etc.) of the substrate W in the end effector 34 constant at all times using the clamp mechanism 344.

[0025] Returning to Figure 1, the alignment module 50 connected to the air transport module 30 aligns the substrate W transported by the transport robot 33. The alignment module 50 includes, for example, a housing 51 capable of housing the substrate W, a rotating stage 52 provided inside the housing 51 on which the substrate W can be placed, a rotational drive mechanism 53 for rotating the rotating stage 52, and an optical sensor 54 for optically detecting the outer edge of the substrate W.

[0026] The housing 51 is formed in the shape of a rectangular box, with its internal space open to the air transport container 31. This allows the transport robot 33 to freely access (move in and out of) the internal space of the housing 51.

[0027] The rotating stage 52 is formed in the shape of a disc with a diameter smaller than the diameter of the substrate W and the distance between the pair of fork plate portions 342 of the end effector 34. The rotation axis of the rotation drive mechanism 53 is connected to the center of the lower surface of the rotating stage 52. Multiple retaining pads 521 (see Figure 4) that hold the lower surface of the substrate W are formed to protrude from the upper surface of the rotating stage 52. In this case, the upper surface of each retaining pad 521 constitutes a mounting surface on which the substrate W is placed. Each retaining pad 521 may be connected to a suction mechanism (not shown) and the substrate W may be attracted by the suction mechanism by applying suction pressure. Alternatively, the rotating stage 52 may be configured to fix the substrate W by other holding means (such as an electrostatic chuck). Furthermore, the rotating stage 52 may have a flat mounting surface without each retaining pad 521.

[0028] The central portion of the substrate W is placed on the rotating stage 52 by the transport robot 33. The rotating stage 52 rotates as the rotation drive mechanism 53 rotates under the command of the control device 90, thereby rotating the substrate W placed on the mounting surface of the rotating stage 52.

[0029] The optical sensor 54 is provided on the outer circumference of the rotating stage 52 and optically detects the outer edge of the substrate W during rotation, as well as the position of a notch (or orientation flat) formed on the substrate W. For example, the optical sensor 54 has a light-emitting unit that emits measurement light and a light-receiving unit that receives the measurement light from the light-emitting unit, and detects the outer edge of the substrate W based on the amount of light of the measurement light that is blocked by the outer edge of the substrate W. As a result, when the substrate W rotates, the control device 90 calculates the circumferential orientation and eccentricity of the substrate W based on the position of the outer edge of the substrate W.

[0030] The control device 90 of the substrate processing system 1 is a computer that controls the entire system and has one or more processors 91, memory 92, input / output interfaces (not shown), and communication interfaces. In the following description, an example will be given in which the control device 90 controls the operation of each module in the substrate processing system 1. Therefore, the control device 90 also functions as a control unit for the air transport module 30 and the alignment module 50, which are part of the substrate transport system. However, the substrate processing system 1 may also be configured to have a dedicated control unit (not shown) for each module, and each control unit operates each module based on control commands from the control device 90.

[0031] One or more processors 91 are a combination of one or more of the following: a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), a circuit consisting of multiple discrete semiconductors, etc., and execute programs stored in memory 92. Memory 92 includes non-volatile memory and volatile memory (e.g., compact discs, DVDs (Digital Versatile Discs), hard disks, flash memory, etc.) and forms the storage unit of the control device 90.

[0032] The processor 91 controls the operation of the transport robot 33 and each module by reading and executing a program stored in the memory 92. The operation control of the control device 90 when transporting the substrate W from the atmospheric transport module 30 to the vacuum transport module 20 will be explained below with reference to Figure 3. Figure 3 is a flowchart showing the processing flow for transporting the substrate W.

[0033] When the control device 90 transports the substrate W from the air transport module 30 to the target processing module 10, it performs steps S1 to S7 in order to transport and align the substrate W in the air transport module 30. First, the control device 90 uses the transport robot 33 to unload the substrate W from the substrate storage case 39 set in a predetermined load port 32 (step S1).

[0034] Next, the control device 90 transports the substrate W using the transport robot 33 and loads the substrate W into the alignment module 50 (step S2). At this time, the transport robot 33 performs a loading operation within the housing 51 to place the substrate W on the upper surface of the rotating stage 52.

[0035] Figure 4 shows the placement operation of the substrate W in the alignment module 50. During the placement operation, the control device 90 controls the movement direction and position of the transport robot 33 according to the operation sequence shown in Figure 4.

[0036] Specifically, as shown in the upper left of Figure 4, the control device 90 first moves the end effector 34 of the transport robot 33 horizontally within the alignment module 50. That is, the substrate W of the end effector 34 enters parallel to the mounting surface of the rotating stage 52. At this time, the end effector 34 extends the frame body 346 and each roller 347 of the clamping mechanism 344, and transports the substrate W by clamping its outer edge between each contact pad 343 and each roller 347. As a result, the end effector 34 can transport the substrate W stably.

[0037] As shown in the upper right of Figure 4, the control device 90 stops the horizontal movement of the transport robot 33 when the center of the substrate W coincides with the rotation center of the rotary stage 52. The control device 90 has prior coordinate information of the rotation center of the rotary stage 52 and recognizes the center information of the substrate W held by the end effector 34 of the transport robot 33. Furthermore, as described above, the end effector 34 holds the substrate W, so the center of the substrate W relative to the end effector 34 can always be kept constant. Therefore, when the substrate W is loaded, the control device 90 can move the end effector 34 horizontally using feedforward control, thereby completing the horizontal movement of the substrate W at a position where the center of the substrate W coincides with the rotation center of the rotary stage 52.

[0038] Furthermore, when the substrate W moves to a position directly above the rotating stage 52, the end effector 34 should retract the frame 346 and each roller 347 of the clamping mechanism 344 to release the clamping of the substrate W by the clamping mechanism 344. This allows the substrate W to be detached from the end effector 34.

[0039] Next, the control device 90 lowers the end effector 34 of the transport robot 33 vertically downward. At this time, the transport robot 33 lowers the end effector 34 so that the rotating stage 52 passes between a pair of fork plate sections 342. The control device 90 has in advance coordinate information of the height of the mounting surface of the rotating stage 52 (holding pad 521). Therefore, the control device 90 lowers the end effector 34 vertically until the position of the lower surface of the substrate W held by the end effector 34 matches the coordinate position of the mounting surface of the rotating stage 52.

[0040] When the control device 90 recognizes that the position of the lower surface of the substrate W coincides with the coordinate position of the mounting surface of the rotating stage 52, it switches to moving the end effector 34 diagonally downwards, inclined with respect to the vertical, as shown in the lower left diagram of Figure 4. In other words, if the end effector 34 continues to descend in the vertical downward direction, there is a possibility that each contact pad 343a of the end effector 34 will interfere with the outer edge of the substrate W and rub against the outer edge of the substrate W. This rubbing increases the risk of misalignment of the substrate W and generation of particles.

[0041] In contrast, by moving the end effector 34 diagonally downward, it is possible to immediately separate the end effector 34 (each contact pad 343a) from the outer edge of the substrate W, thereby avoiding mutual interference. Specifically, the end effector 34 moves in the direction of its advance relative to the alignment module 50 and vertically downward. This is because, in the released state of the clamping mechanism 344, the leading edge of the outer edge of the substrate W is in contact with each contact pad 343a of each fork plate portion 342.

[0042] The angle θ of the direction of movement of the end effector 34 relative to the horizontal direction (see Figure 7) is not particularly limited as long as interference between the end effector 34 and the substrate W can be reliably avoided, and can be set in a range of approximately 30° to 85°, for example. In this embodiment, the angle θ of the direction of movement is set to 45°.

[0043] The substrate W is placed on the rotating stage 52 when the end effector 34 is lower than the mounting surface of the rotating stage 52. The control device 90 moves the end effector 34 diagonally downward over a predetermined distance. Then, as shown in the lower right diagram of Figure 4, the control device 90 retracts the end effector 34 horizontally to a height lower than the rotating stage 52. This allows the end effector 34 to exit with the substrate W loaded into the alignment module 50.

[0044] Returning to Figure 3, after loading the substrate into the alignment module 50, the control device 90 rotates the rotary stage 52 to measure the eccentricity and notch position of the substrate W (step S3). Based on this, the control device 90 calculates the circumferential orientation and positional deviation of the substrate W and appropriately controls the movement of the transport robot 33 or the operation of the rotary stage 52 to transport the substrate W with improved circumferential orientation and positional deviation.

[0045] The control device 90 causes the transport robot 33 to enter the alignment module 50, receive the substrate W from the rotating stage 52, and unload the substrate W from the alignment module 50 (step S4). When receiving the substrate W, the control device 90 corrects the movement of the transport robot 33 according to the circumferential orientation and positional deviation calculated by the alignment module 50, so that the substrate W can be received.

[0046] Then, the control device 90 loads the substrate W, which has been unloaded from the alignment module 50 by the transport robot 33, into the load lock module 40 (step S5). When the substrate W is placed on the stage 42 of the load lock module 40, the control device 90 may correct the movement of the transport robot 33 according to the circumferential orientation and positional misalignment calculated by the alignment module 50 to transfer the substrate W.

[0047] Subsequently, the control device 90 reduces the pressure inside the load lock module 40 into a vacuum atmosphere, and then the vacuum transfer robot 22 removes the substrate W from the load lock module 40 (step S6). Furthermore, the control device 90 uses the vacuum transfer robot 22 to load the substrate W into the target processing module 10 (step S7). Even when placing the substrate W on the stage 12 of the processing module 10, the movement of the vacuum transfer robot 22 may be corrected according to the circumferential orientation and positional deviation calculated by the alignment module 50 to transfer the substrate W.

[0048] As described above, the substrate processing system 1 can transport the substrate W aligned to the load lock module 40 by measuring the eccentricity of the substrate W and the position of the notch in the alignment module 50. This enables the substrate processing system 1 to accurately place the substrate W on the stage 12 of the processing module 10, and to stably perform substrate processing by the processing module 10.

[0049] Incidentally, the substrate W that undergoes substrate processing in the substrate processing system 1 may have warping. For example, multiple films are laminated on the substrate W, and the difference in thermal expansion during the deposition of each film puts stress on the substrate W, causing it to warp. As an example, as shown in Figure 5, the warping of the substrate W is such that the area near the center of the substrate W is higher than the outer edge of the substrate W, in other words, the area near the center of the substrate W is formed to be convex upward in the vertical direction (hereinafter, this form will be called convex warping). Figure 5 is a diagram showing the placement operation of a substrate W with convex warping in the alignment module 50.

[0050] The substrate processing system 1 also performs the above-described placement operation when transporting the convexly warped substrate W by the transport robot 33 and loading the alignment module 50. In this placement operation, when the substrate processing system 1 moves the end effector 34 diagonally downward, the substrate W is placed with a misalignment relative to the mounting surface of the rotating stage 52.

[0051] Specifically, as shown in the upper left and upper right diagrams of Figure 5, the control device 90 performs an operation to slide the end effector 34 horizontally, and then performs an operation to lower the end effector 34 vertically downward. When the end effector 34 is lowered, the control device 90 moves the end effector 34 by a distance (downward movement distance) such that the height position of the lower surface of the substrate W, based on the position information of the end effector 34, coincides with the height position of the mounting surface of the rotating stage 52.

[0052] However, the convex curve of the substrate W is curved away from the retaining pad 521. Therefore, even if the position of the substrate W and the coordinate position of the mounting surface of the rotary stage 52 match in the position information of the end effector 34 in the control device 90, the actual substrate W does not come into contact with the mounting surface of the rotary stage 52, as shown in the lower left of Figure 5.

[0053] Therefore, when the end effector 34 moves diagonally downward, the convex-curved substrate W also moves diagonally downward together with the end effector 34. Then, as the convex-curved substrate W moves diagonally downward, it comes into contact with the mounting surface of the rotating stage 52 and is held in place by the rotating stage 52. Meanwhile, the end effector 34 continues to move diagonally downward.

[0054] As shown in the lower right diagram of Figure 5, the convex-curved substrate W is placed on the mounting surface of the rotating stage 52 with a misalignment in the direction of the end effector 34's advance (towards the back of the alignment module 50). The amount of misalignment ΔP that occurs when the convex-curved substrate W is placed corresponds to the eccentricity, which is the difference between the center of the substrate W and the center of the rotating stage 52.

[0055] The amount of convex warping (warping amount) that occurs in the substrate W can be expressed as the difference between the center of the bottom (or top) surface of the substrate W and the outer edge of the bottom (or top) surface of the substrate W. The amount of warping of the substrate W is small, for example, about 10 μm to 1 mm, and it is difficult to recognize the amount of warping of the substrate W in advance by visual inspection or other means without using a device to measure the shape of the substrate W. If the substrate W is misaligned due to the effect of warping, the substrate W will be transported in a misaligned state even after being transferred from the atmospheric transport module 30 to the vacuum transport module 20. Therefore, the substrate processing system 1 according to this embodiment is configured to measure the eccentricity of the substrate W using the alignment module 50, estimate the amount of warping of the substrate W using that eccentricity, and eliminate the misalignment corresponding to the amount of warping of the substrate W.

[0056] The following describes how to estimate the amount of warpage of the substrate W, with reference to Figures 6 and 7. Figure 6(A) is a graph illustrating the results of measuring the position of the outer edge of a substrate W without warpage using the alignment module 50. Figure 6(B) is a graph illustrating the results of measuring the position of the outer edge of a substrate W with convex warpage using the alignment module 50. Figure 7 is a side view illustrating the principle of estimating the amount of warpage from the eccentricity of the substrate W.

[0057] The alignment module 50 rotates the rotary stage 52 and measures the position of the outer edge of the substrate W, which is not warped, using the optical sensor 54. In this case, as shown in Figure 6(A), the position of the outer edge of the substrate W will have a sufficiently small amplitude (or zero amplitude). The sharply protruding peaks 100 in Figure 6(A) and the sharply protruding peaks 101 in Figure 6(B) are the locations where notches formed on the outer edge of the substrate W were detected.

[0058] As described above, the end effector 34 of the transport robot 33 according to this embodiment transports the substrate W while gripping it. Therefore, even when transporting multiple different substrates W, the end effector 34 can always carry the substrate W, which is held in the same position, into the alignment module 50 and place it on the rotating stage 52. Even if the position of the outer edge of the substrate W placed on the rotating stage 52 changes slightly in the circumferential direction due to distortion of the outer edge of the substrate W itself, the amplitude of the outer edge position in the measurement results of the alignment module 50 becomes sufficiently small.

[0059] In contrast, when the position of the outer edge of the convexly warped substrate W is measured by the alignment module 50, the amplitude of the outer edge of the substrate W increases, as shown in Figure 6(B). That is, the end effector 34 always loads the substrate W, which is held in the same position, into the alignment module 50, but the convexly warped substrate W becomes eccentric with respect to the rotating stage 52 due to the above-mentioned mounting operation. Therefore, there is a large difference in the amount of amplitude of the outer edge position when measuring the position of the outer edge of a substrate W that is not warped compared to when measuring the position of the outer edge of a substrate W that is convexly warped.

[0060] The amount of eccentricity ΔP (shift in position of the center of the substrate W relative to the rotation center of the rotating stage 52) changes according to the amount of convex warping. The control device 90 calculates the amount of displacement ΔP of the substrate W using the measurement results of the position of the outer edge of the convex warped substrate W shown in Figure 6(B), and further estimates (calculates) the amount of warping of the substrate W based on this displacement ΔP.

[0061] Specifically, as shown in Figure 7, the end effector 34 places the convexly curved substrate W onto the rotating stage 52 when it moves diagonally downward from the intended placement position of the substrate W during the placement operation. Therefore, the amount of displacement ΔP of the convexly curved substrate W varies depending on the angle θ of the direction of movement of the end effector 34. For example, when the angle θ of the direction of movement is large, the end effector 34 moves along a path close to the vertical, and the amount of displacement ΔP becomes small. Conversely, when the angle θ of the direction of movement is small, the end effector 34 moves away from the vertical, and the amount of displacement ΔP becomes large.

[0062] The angle θ of the diagonally downward movement of the end effector 34 is a preset value (45° in this embodiment). When the angle θ of the movement direction is 45°, the displacement amount ΔP of the substrate W matches the distance ΔD (i.e., the amount of warping) from the bottom surface of the substrate W to be placed to the actual bottom surface of the substrate W that has risen due to warping. In other words, displacement amount ΔP = distance ΔD. In this way, the control device 90 can estimate the amount of warping of the substrate W based on the calculation of the eccentricity of the substrate W by the alignment module 50. Note that even if the angle θ of the movement direction of the end effector 34 is not 45°, the amount of warping of the substrate W can be estimated by calculating the displacement amount ΔP × tanθ.

[0063] The control device 90 can then use the estimated amount of warping of the substrate W to correct the movement of the substrate W using the transport robot 33, thereby eliminating any misalignment of the substrate W. For example, the control device 90 measures the eccentricity of the substrate W using the alignment module 50, and then transports the substrate from the alignment module 50 to the load lock module 40 (see step S5 in Figure 3). When the transport robot 33 places the substrate W on the stage 42 of the load lock module 40, it performs movement correction according to the amount of warping of the substrate W.

[0064] Figure 8 shows the loading operation of the substrate W in the load lock module 40. As shown in the upper part of Figure 8, the control device 90 performs the same operation in the loading operation of the load lock module 40 as in the loading operation of the alignment module 50. This makes it possible to avoid misalignment and particle generation caused by friction between the end effector 34 and the outer edge of the substrate W.

[0065] Specifically, the control device 90 performs an operation to slide the end effector 34 horizontally within the load lock module 40, and then performs an operation to lower the end effector 34 vertically downward. When the end effector 34 is lowered, the control device 90 moves the end effector 34 by a distance (downward movement distance) such that the height position of the lower surface of the substrate W, based on the position information of the end effector 34, coincides with the height position of the mounting surface of the stage 42.

[0066] The control device 90 performs movement correction according to the amount of warping of the convex-warped substrate W when the end effector 34 is lowered. The two figures on the left of Figure 8 show the placement operation of the convex-warped substrate W with movement correction applied, and the two figures on the right of Figure 8 show the placement operation of the convex-warped substrate W without movement correction as a comparative example.

[0067] If no movement correction is performed, the end effector 34 begins to move diagonally downward while the underside of the convex-curved substrate W is not in contact with the mounting surface of the stage 42. As a result, the convex-curved substrate W is mounted in a misaligned position relative to the stage 42.

[0068] In response to this, the control device 90 adds the estimated amount of warping of the substrate W to the preset travel distance of the end effector 34 when the end effector 34 descends. As a result, when movement correction is performed, the travel distance of the end effector 34 becomes longer by the amount of warping compared to when movement correction is not performed. Consequently, the descent of the end effector 34 can be stopped at a position where the lower surface of the substrate W and the mounting surface of the stage 42 are in contact. After that, even if the end effector 34 moves diagonally downward, the substrate W is maintained in the mounting position on the stage 42.

[0069] In other words, the substrate processing system 1 can place the substrate W in the load lock module 40 with the center of the convex-curved substrate W aligned with the center of the stage 42 by performing movement correction. Therefore, the vacuum transport robot 22 of the vacuum transport module 20 can take out the substrate W that has been accurately placed in the load lock module 40 and transport the substrate W to any of the processing modules 10A to 10D. The substrate processing system 1 may also perform movement correction according to the amount of curvature of the substrate W when the convex-curved substrate W is being transported to the processing modules 10A to 10D by the vacuum transport robot 22. This allows the substrate processing system 1 to place the convex-curved substrate W on the stage 12 with even greater accuracy.

[0070] The substrate processing system 1 according to this embodiment is not limited to the above embodiment and can be modified in various ways. For example, the control device 90 according to the above embodiment converts the measurement result of the alignment module 50 (eccentricity of the substrate W) directly into the amount of warping of the substrate W and performs movement correction according to the amount of warping. However, the control device 90 may also have a threshold value for comparing the eccentricity of the substrate W and be configured to compare the eccentricity measured by the alignment module 50 with the threshold value. The control device 90 does not perform movement correction when the eccentricity is less than the threshold value, but performs movement correction when the eccentricity is greater than or equal to the threshold value. By comparing the eccentricity and the threshold value in this way, it becomes possible to exclude changes in the eccentricity due to distortion of the outer edge of the substrate W itself, and only the substrate W that is warped can be effectively moved.

[0071] [Second Embodiment] The warp of the substrate W may be such that the area near the center of the substrate W is lower than the outer edge of the substrate W, in other words, the area near the center of the substrate W is concave downwards in the vertical direction (hereinafter, this form will be referred to as concave warp). Therefore, the substrate processing system 1 according to the second embodiment is configured to distinguish between a substrate W with convex warp and a substrate W with concave warp and estimate the amount of warp. Figure 9 is a diagram showing the mounting operation of the end effector 34 of the substrate processing system 1 according to the second embodiment. Specifically, the substrate processing system 1 according to the second embodiment performs the diagonal downward movement of the end effector 34 during the mounting operation for a longer period than the mounting operation according to the first embodiment.

[0072] As shown in the upper left of Figure 9, the control device 90 first moves the end effector 34 of the transport robot 33 horizontally within the alignment module 50. Then, as shown in the upper right of Figure 9, the control device 90 stops the horizontal movement of the transport robot 33 at a slide stop position before the center of the substrate W coincides with the rotation center of the rotating stage 52.

[0073] The slide stop position is set so that when the end effector 34 is moved diagonally downward, the position of the lower surface of the substrate W (coordinate position in the Z-axis direction) coincides with the coordinate position of the mounting surface of the rotating stage 52, and the center of the substrate W coincides with the rotation center of the rotating stage 52. Since the control device 90 pre-defines the angle θ in the diagonal downward movement direction, the slide stop position can also be calculated in advance, and the end effector 34 can be continuously moved diagonally downward based on this slide stop position.

[0074] The control device 90 moves the end effector 34 of the transport robot 33 diagonally downward from the slide stop position. The control device 90 has prior information on the coordinate position of the mounting surface of the rotating stage 52, and can recognize the position where the position of the lower surface of the substrate W held by the end effector 34 coincides with the coordinate position of the mounting surface of the rotating stage 52 when moving diagonally downward (see the lower left diagram of Figure 9). However, even when the lower surface of the substrate W is in contact with the mounting surface of the rotating stage 52 and the control device recognizes that the substrate W is placed on the rotating stage 52, the diagonal downward movement is continued to ensure that the substrate W is reliably released from the end effector 34.

[0075] In other words, the control device 90 moves the end effector 34 diagonally downward over a long distance from the slide stop position. Then, as shown in the lower right diagram of Figure 9, the control device 90 retracts the end effector 34 horizontally at a height lower than the rotating stage 52. This allows the end effector 34 to exit with the substrate W loaded into the alignment module 50.

[0076] Figure 10(A) shows an example of placing a convexly warped substrate W using the placement operation of the second embodiment. Figure 10(B) shows an example of placing a concavely warped substrate W using the placement operation of the second embodiment. In the placement operation of the second embodiment as well, the substrate W with convex warping is placed with a position shifted toward the rear in the direction of travel of the end effector 34 relative to the rotation center of the rotating stage 52. As described above, this is because the diagonal downward movement by the end effector 34 continues at a position where the position of the lower surface of the substrate W and the coordinate position of the placement surface of the rotating stage 52 coincide.

[0077] On the other hand, in the placement operation of the second embodiment, the concave-curved substrate W is placed on the mounting surface before the position of the lower surface of the substrate W recognized by the control device 90 coincides with the coordinate position of the mounting surface of the rotating stage 52, because the lower surface of the substrate W protrudes from the outer edge. As a result, the concave-curved substrate W is placed in a position offset to the front of the direction of travel of the end effector 34 relative to the rotation center of the rotating stage 52.

[0078] Figure 11 is a graph illustrating the results of measuring the position of the outer edge of a concave-warped substrate W using the alignment module 50. In Figure 11, the dashed line represents the result of measuring the position of the outer edge of a convex-warped substrate W. When the position of the outer edge of a concave-warped substrate W is measured, the alignment module 50 detects the position of the outer edge as shown by the solid line in Figure 11. For example, if the amount of warping is the same, the convex-warped substrate W and the concave-warped substrate W will exhibit amplitudes such that the phase at the position of the outer edge of the substrate W is shifted by exactly 180°.

[0079] Therefore, the control device 90 can determine whether the substrate W is convex or concave by capturing the circumferential phase of the position of the outer edge of the substrate W. The control device 90 can then calculate the eccentricity (positional displacement ΔP) of the substrate W from the amplitude of the position of the outer edge of the substrate W. In this case, the positional displacement ΔP of the substrate W with concave warping should be calculated as a negative number compared to the positional displacement ΔP of the substrate W with convex warping. Furthermore, the control device 90 can estimate the amount of warping of the substrate W with convex warping or the amount of warping of the substrate W with concave warping (negative value) based on the eccentricity. In other words, after performing the above-described mounting operation of the end effector 34, the control device 90 can easily and accurately estimate the direction of the warping of the substrate W (convex or concave warping) and the amount of warping by measuring the position of the outer edge of the substrate W with the alignment module 50.

[0080] Furthermore, if the substrate processing system 1 is aware in advance of the presence of a concave or warped substrate W, it may move the end effector 34 diagonally downward before placing the substrate W on the mounting surface of the rotating stage 52. After recognizing the agreement between the position of the lower surface of the substrate W and the coordinate position of the mounting surface on the rotating stage 52, the end effector 34 may then be moved vertically downward. Even in this case, the control device 90 can accurately calculate the amount of warping of the concave or warped substrate W.

[0081] [Variation] Figure 12 is an explanatory diagram showing a modified substrate processing system 1A. The substrate processing system 1A may include stages 13 and 14 for processing modules 10A to 10D according to the direction of warping of the substrate W (convex warp, concave warp). For example, in Figure 12, processing module 10B includes a convex stage 13 whose mounting surface is raised vertically above the outer periphery, while processing module 10C includes a concave stage 14 whose mounting surface is recessed vertically below the outer periphery.

[0082] Then, when the control device 90 of the substrate processing system 1A recognizes the direction of warping of the substrate W using the alignment module 50, it transports the substrate W to the appropriate processing module 10A to 10D according to the state of warping of the substrate W. For example, substrates W without warping are transported to processing module 10A or processing module 10D, substrates W with convex warping are transported to processing module 10B, and substrates with concave warping are transported to processing module 10C. As a result, processing modules 10A to 10D can stably and accurately place the substrate W transported by the vacuum transport robot 22 on stages 12, 13, and 14 and perform substrate processing.

[0083] Furthermore, the substrate processing system 1A may be configured such that the mounting surfaces of stages 12, 13, and 14 themselves are deformable, and the direction and amount of deformation of the mounting surfaces are adjusted according to the estimated direction (convex or concave) and amount of warping of the substrate W.

[0084] The technical concept and effects of this disclosure, as described in the embodiments above, are described below.

[0085] A substrate transport method according to a first aspect of this disclosure includes the steps of (A) placing the substrate W on the stage of the alignment module 50 based on the transport robot 33 holding the substrate W with a transport robot 33 and transporting the substrate W into the alignment module 50, and the transport robot 33 passing over the stage (rotating stage 52) of the alignment module 50; (B) measuring the eccentricity of the substrate W with the alignment module 50 and estimating the amount of warping of the substrate W based on the measured eccentricity of the substrate W; and (C) transporting the substrate W discharged from the alignment module 50 into another module (load lock module 40) based on the estimated amount of warping of the substrate W. These steps are performed in this order, and in step (A), the substrate W is moved diagonally downward relative to the stage of the alignment module 50.

[0086] According to the above, the substrate transport method can easily and accurately estimate the warp of the substrate W based on the eccentricity of the substrate W placed on the stage (rotating stage 52) of the alignment module 50. As a result, the substrate transport method can transport the substrate W appropriately according to the estimated amount of warp of the substrate W, thereby stabilizing transport and improving the accuracy of substrate processing.

[0087] Furthermore, in step (A), the substrate W is moved diagonally downward before the control device 90 recognizes that the substrate W has been placed on the stage (rotating stage 52) of the alignment module 50, and the substrate W is also moved diagonally downward after the control device 90 recognizes that the substrate W has been placed on the stage of the alignment module 50. In this way, the substrate transport method makes it possible to recognize various types of substrate warping by moving the substrate W diagonally downward from before it is placed on the stage to after it is placed.

[0088] Furthermore, the warp of the substrate W exhibits either a convex warp, where the center protrudes vertically upward from the outer edge, or a concave warp, where the center protrudes vertically downward from the outer edge. In step (B), the convex or concave warp of the substrate W is determined based on the phase of the outer edge of the substrate W when the eccentricity of the substrate W is measured by the alignment module 50. As a result, the substrate transport method can accurately determine whether the substrate W is convex or concave based on the measurement results of the alignment module 50.

[0089] Another module includes a load lock module 40 that can switch between an atmospheric and a vacuum atmosphere, a vacuum transport module 20 connected to the load lock module 40, and a plurality of processing modules 10 connected to the vacuum transport module 20. In step (C), the substrate W is transported to the plurality of processing modules 10 via the load lock module 40 and the vacuum transport module 20. This allows the substrate transport method to accurately transport the substrate W to the target processing module 10 based on the amount of warpage of the substrate W.

[0090] Furthermore, at least one of the multiple processing modules 10 has a convex mounting surface for the substrate W, and if a substrate W with convex warping is detected in step (B), the substrate W with convex warping is transported to the processing module 10B having a convex mounting surface in step (C). This allows the substrate transport method to stably place the substrate W with convex warping onto the stage 13 of the processing module 10B.

[0091] Furthermore, at least one of the multiple processing modules 10 has a concave mounting surface for the substrate W. If a concave-warped substrate W is detected in step (B), the convex-warped substrate W is transported to the processing module 10C having a concave mounting surface in step (C). This allows the substrate transport method to stably place the concave-warped substrate W on the stage 14 of the processing module 10C.

[0092] Furthermore, in step (A), the substrate W is moved vertically downward before the control device 90 recognizes that the substrate W has been placed on the stage (rotating stage 52) of the alignment module 50, and then moved diagonally downward after the control device 90 recognizes that the substrate W has been placed on the stage of the alignment module 50. In this way, the substrate transport method also makes it possible to accurately recognize the amount of warping of a convexly warped substrate W by moving it vertically downward before placing it on the stage and then moving it diagonally downward after placing it.

[0093] Furthermore, in step (B), the amount of warping of the substrate W is calculated based on the eccentricity of the substrate W due to the alignment module 50 and the angle θ in the direction of diagonal downward movement of the substrate W. This allows the substrate transport method to calculate the amount of warping of the substrate W more easily and accurately.

[0094] Furthermore, in step (C), the movement of the transport robot 33 is corrected within another module (load lock module 40) based on the estimated amount of warping of the substrate W, and the substrate W is placed on the stage 42 of the other module. This allows the substrate transport method to avoid misalignment of the substrate W when placing a warped substrate W onto another module.

[0095] Furthermore, in step (C), when the substrate W is moved to be placed on the stage 42 of another module (load lock module 40), the amount of warping of the substrate W is added to align the mounting surface of the stage 42 of the other module with the bottom surface of the substrate W. As a result, the substrate transport method can accurately place the warped substrate W onto the stage 42 of the other module.

[0096] Furthermore, in step (A), before placing the substrate W on the stage 42 of the alignment module 50, the transport robot 33 clamps the outer edge of the substrate W with a clamping mechanism 344 on the end effector 34 that supports the substrate W, thereby maintaining a constant position of the substrate W relative to the end effector 34 during transport. In this way, the end effector 34 can transport the substrate W while maintaining a constant position of the substrate W, making it possible to accurately place the substrate W on the rotating stage 52 of the alignment module 50, etc.

[0097] Furthermore, a second aspect of this disclosure is a substrate processing system 1 comprising a transport robot 33 for holding and transporting a substrate W, an alignment module 50 for measuring the eccentricity of the substrate W, another module (load lock module 40) to which the substrate W discharged from the alignment module is transported, and a control device 90, wherein the control device 90 controls in this order: (A) the transport robot 33 loads the substrate W into the alignment module 50 and the transport robot 33 passes over the stage (rotating stage 52) of the alignment module 50, thereby placing the substrate W on the stage of the alignment module 50; (B) the alignment module 50 measures the eccentricity of the substrate W and estimates the amount of warping of the substrate W based on the measured eccentricity of the substrate W; and (C) the substrate W discharged from the alignment module 50 is loaded into another module based on the estimated amount of warping of the substrate W, and in step (A), the substrate W is moved diagonally downward relative to the stage of the alignment module 50. Even in this case, the substrate processing system 1 can easily and accurately estimate the warpage of the substrate W.

[0098] The substrate transport method and substrate processing system 1 according to the embodiments disclosed herein are illustrative and not restrictive in all respects. The embodiments can be modified and improved in various ways without departing from the scope and spirit of the appended claims. The matters described in the above embodiments can be otherwise configured and combined in a non-consistent manner. [Explanation of Symbols]

[0099] 1. Substrate Processing System 10 Processing Modules 33 Transport robots 40 Load Lock Module 50 Alignment Modules 52-rotation stage 90 Control device W board

Claims

1. (A) A process in which the substrate is held by a transport robot and transported into the alignment module, and the substrate is placed on the stage of the alignment module based on the transport robot passing over the stage of the alignment module, (B) A step of measuring the eccentricity of the substrate using the alignment module and estimating the amount of warping of the substrate based on the measured eccentricity of the substrate, (C) The process of loading the substrate removed from the alignment module into another module based on the estimated amount of warping of the substrate is carried out in this order. In step (A) above, the substrate is moved diagonally downward relative to the stage of the alignment module. A method for transporting circuit boards.

2. In step (A) above, the substrate is moved diagonally downward before the control device recognizes that the substrate has been placed on the stage of the alignment module, and the substrate is moved diagonally downward even after the control device recognizes that the substrate has been placed on the stage of the alignment module. The substrate transport method according to claim 1.

3. The warp of the substrate exhibits one of two states: a convex warp where the center protrudes vertically upward from the outer edge, or a concave warp where the center protrudes vertically downward from the outer edge. In step (B) above, a convex or concave warp of the substrate is determined based on the phase of the outer edge of the substrate when the eccentricity of the substrate is measured by the alignment module. The substrate transport method according to claim 2.

4. The aforementioned other module is, A load lock module that can switch between atmospheric and vacuum environments, A vacuum transfer module connected to the load lock module, The vacuum transport module includes a plurality of processing modules connected to the vacuum transport module, In step (C) above, the substrate is transported to the plurality of processing modules via the load lock module and the vacuum transport module. The substrate transport method according to claim 3.

5. At least one of the plurality of processing modules has a mounting surface on the substrate formed in a convex shape, If the substrate is determined to be convex in step (B), then in step (C), the convex substrate is transported to the processing module having the convex mounting surface. The substrate transport method according to claim 4.

6. At least one of the plurality of processing modules has a mounting surface on the substrate that is formed in a concave shape. If the substrate is found to be concave in step (B), then in step (C), the substrate is transported to the processing module having the concave mounting surface. The substrate transport method according to claim 4.

7. In step (A) above, the substrate is moved vertically downward before the control device recognizes that the substrate has been placed on the stage of the alignment module, and the substrate is moved diagonally downward after the control device recognizes that the substrate has been placed on the stage of the alignment module. The substrate transport method according to claim 1.

8. In step (B) above, the amount of warping of the substrate is calculated based on the eccentricity of the substrate by the alignment module and the angle of the diagonally downward movement of the substrate. A substrate transport method according to any one of claims 1 to 7.

9. In step (C) above, the movement of the transport robot is corrected within the other module based on the estimated amount of warping of the substrate, and the substrate is placed on the stage of the other module. A substrate transport method according to any one of claims 1 to 7.

10. In step (C) above, when the substrate is moved to be placed on the stage of the other module, the amount of warping of the substrate is added to bring the mounting surface of the stage of the other module and the lower surface of the substrate to match. The substrate transport method according to claim 9.

11. In step (A) above, before placing the substrate on the stage of the alignment module, the transport robot clamps the outer edge of the substrate with a clamping mechanism on the end effector that supports the substrate, thereby maintaining a constant position of the substrate relative to the end effector during transport. A substrate transport method according to any one of claims 1 to 7.

12. A transport robot that holds and transports a circuit board, A positioning module for measuring the eccentricity of the aforementioned substrate, Another module to which the substrate discharged from the alignment module is transported, A substrate processing system comprising a control device, The control device is (A) A step of loading the substrate into the alignment module using the transport robot and placing the substrate on the stage of the alignment module based on the transport robot passing over the stage of the alignment module, (B) A step of measuring the eccentricity of the substrate using the alignment module and estimating the amount of warping of the substrate based on the measured eccentricity of the substrate, (C) The process of loading the substrate removed from the alignment module into another module based on the estimated amount of warping of the substrate is controlled in this order. In step (A) above, the substrate is moved diagonally downward relative to the stage of the alignment module. PCB processing system.

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