A photolithography machine silicon wafer stage moving mechanism

Abstract

The present invention discloses a photolithography machine silicon wafer stage moving mechanism, which relates to the field of silicon wafer processing technology, including two groups of silicon wafer carriers that can move back and forth along a rectangular path, each group is composed of two laterally distributed silicon wafer carriers, and four silicon wafer carriers are arranged in a field shape. In the initial state, the silicon wafer carrier located in the upper right corner of the four silicon wafer carriers is directly opposite to the processing station of the photolithography machine. It also includes two material changing units. In the initial state, one of the two groups of silicon wafer carriers is located on the processing path, and the other group is located on one of the material changing paths. During the operation of the present invention, the processing station on the processing path can continuously perform processing operations on the silicon wafer in the silicon wafer carrier, the material changing path can continuously receive the silicon wafer carrier after processing, and the material changing unit can synchronously perform material changing operations on the silicon wafer carrier after processing. It does not affect the implementation of the processing operation, and can quickly perform processing operations on multiple silicon wafer raw materials, thereby improving the work efficiency of the photolithography machine in processing silicon wafers.

Description

Technical Field

[0001] The present invention relates to the technical field of silicon wafer processing, and particularly relates to a moving mechanism for a silicon wafer stage of a lithography machine. Background Art

[0002] A lithography machine, also known as a mask aligner and exposure machine, is the core equipment in the lithography process of the chip manufacturing process. The lithography process accounts for about 35% of the overall manufacturing cost in the chip manufacturing process and determines the critical dimensions of the chip. The lithography machine has a complex structure, including parts such as a silicon wafer stage, a light source, an optical system, and a control system. Its working principle is mainly to use specific light (generally ultraviolet light, deep ultraviolet light, extreme ultraviolet light) to pass through a mask plate containing target pattern information and irradiate it on the surface of the substrate, causing the photoresist irradiated by the light to react, so as to form a different effect after development from the unirradiated area. In the entire chip manufacturing process, generally 20 - 30 times of lithography are required, which takes up 50% of the IC production link and accounts for 1 / 3 of the chip production cost.

[0003] The silicon wafer stage is one of the core subsystems of the lithography machine, which directly determines the critical dimensions, overlay accuracy, and production efficiency that the lithography machine can achieve. Most of the existing silicon wafer stages of lithography machines adopt a dual-stage exchange system. The dual-stage exchange system includes a base, two silicon wafer stages with the same structure that work at the preprocessing station and the exposure station respectively, and a silicon wafer stage driving device. However, in the existing dual-stage exchange system, when the silicon wafers in the silicon wafer stages at the preprocessing station and the exposure station are processed, the silicon wafer stage still needs to move to remove the processed silicon wafers and replenish the silicon wafers to be processed, and perform the material change operation. During the entire material change process, the silicon wafer stage cannot perform processing operations, resulting in a reduction in the efficiency of silicon wafer processing. Summary of the Invention

[0004] In view of the above problems, the present application provides a moving mechanism for a silicon wafer stage of a lithography machine.

[0005] To achieve the above object, the present application provides the following technical solution: A moving mechanism for a silicon wafer stage of a lithography machine includes two groups of silicon wafer carriers that can reciprocate along a rectangular path. Each group is composed of two laterally distributed silicon wafer carriers, and the four silicon wafer carriers are arranged in a cross shape. In the initial state, the silicon wafer carrier in the upper right corner among the four silicon wafer carriers faces the processing station of the lithography machine.

[0006] It also includes two material change units. The two material change units and the processing station form two material change paths distributed from front to back and a processing path located between the two material change paths. In the initial state, one of the two groups of silicon wafer carriers is located on the processing path, and the other group is located on one of the material change paths.

[0007] When the two groups of wafer stages move simultaneously along the X-axis direction, the processing station can successively perform photolithography processing operations on one group of wafer stages, and the material changing unit can successively perform material changing operations on the other group of wafer stages. When the four wafer stages move towards the Y-axis, the two wafer stages on which the material changing operations are completed move to the processing path, and the two wafer stages on which the processing is completed move to another material changing path. When the four wafer stages move reciprocally along the rectangular path, there are always two wafer stages on the four wafer stages located on the processing path, and the other two wafer stages are located on the material changing path.

[0008] Further, a slide table and a table surface arranged in parallel with the slide table are provided below the wafer stage. The bottom end of the slide table is connected to an X-axis moving frame through a support frame. The X-axis moving frame has a U-shaped structure, and a first driving rack arranged along the X direction is provided inside the X-axis moving frame.

[0009] A first driving gear meshing with the first driving rack and a first driving motor capable of driving the first driving gear to rotate are provided on the table surface. When the X-axis moving frame, the support frame, and the slide table move synchronously, the two groups of wafer stages move respectively within the material changing path and the processing path.

[0010] Further, a traveling roller group capable of moving synchronously with the slide table is provided at the bottom end of the slide table. A guiding track adapted to the traveling roller group is provided on the table surface, and a first guiding roller group is provided on the table surface. A channel capable of accommodating the first guiding roller group to pass through is provided on the X-axis moving frame.

[0011] Further, a connecting beam is provided below the wafer stage. A Y-axis moving frame is provided on the connecting beam. The Y-axis moving frame has a U-shaped structure, and a second driving rack arranged along the Y-axis direction is provided inside the Y-axis moving frame.

[0012] A second driving gear meshing with the second driving rack and a second driving motor capable of driving the second driving gear to rotate are provided on the slide table. When the Y-axis moving frame and the connecting beam move synchronously, the two groups of wafer stages switch positions on the material changing path and the processing path.

[0013] Further, a second guiding roller group arranged along the Y-axis direction is provided on the slide table. Channels capable of accommodating the second guiding roller group to pass through are provided on both the connecting beam and the Y-axis moving frame.

[0014] Further, each of the material changing units includes a material changing arm in an L shape. Suction cups are provided on both arm bodies of the material changing arm that are vertically distributed. A storage rack and a material changing rack are respectively provided on both sides of the material changing arm. One arm body of the material changing arm is located directly above the wafer stage, and the other arm body is located directly above the material changing rack. When the material changing arm rotates, the two suction cups can transfer the wafers originally inside the material changing rack to the inside of the wafer stage, and at the same time transfer the wafers inside the wafer stage to the inside of the storage rack.

[0015] Further, the material changing unit further includes an electric rotating seat provided at the bending position of the material changing arm. An installation plate is provided on the electric rotating seat and is located directly below the material changing arm. A cylinder is provided on the installation plate. The push rod at the output end of the cylinder is connected to the material changing arm. When the material changing arm moves up and down, the suction cups located directly above the wafer stage and the material changing rack move synchronously until they come into contact with the wafers.

[0016] Further, brackets capable of carrying wafers are provided inside both the storage rack and the material changing rack. A pair of driving protrusions are provided on each bracket. Channels capable of accommodating the movement of the driving protrusions are provided on both the storage rack and the material changing rack. Electric lead screws and limit rods perpendicular to the brackets are provided on the outer sides of both the storage rack and the material changing rack. The pair of driving protrusions are respectively installed on the electric lead screw and the limit rod. When the driving protrusions move, the distance between the bracket and the suction cup above it can be adjusted.

[0017] In summary, the technical effects and advantages of the present invention are as follows:

[0018] 1. The present invention is provided with four wafer stages that can reciprocate along a rectangular path. During the operation of the entire moving mechanism, there are always two wafer stages on the four wafer stages located on the processing path, and the other two wafer stages are located on the material changing path. The processing stations on the processing path can continuously perform processing operations on the wafers inside the wafer stage. The material changing path can continuously receive the wafer stages after processing, and the material changing unit can synchronously perform material changing operations on the wafer stages after processing. At the same time, without affecting the implementation of the processing operation, multiple wafer raw materials can be quickly processed, improving the working efficiency of the lithography machine for processing wafers.

[0019] 2. During the operation of the material changing unit in the present invention, the two suction cups can transfer the wafers originally inside the material changing rack to the inside of the wafer stage, and at the same time transfer the wafers inside the wafer stage to the inside of the storage rack. Therefore, when the material changing arm rotates, the feeding and loading operations can be synchronously implemented, reducing the time required for repeatedly operating the wafers and improving the efficiency of wafer material changing and processing operations. Description of the Drawings

[0020] To more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the accompanying drawings required for the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only some embodiments of the present application. For those skilled in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0021] Figure 1 Schematic diagram of the three-dimensional structure of the present invention.

[0022] Figure 2 Schematic diagram of the second perspective of the present invention.

[0023] Figure 3 Schematic diagram of the tabletop structure of the present invention.

[0024] Figure 4 Schematic diagram of the structure when the wafer carrier stage of the present invention is connected to the sliding stage.

[0025] Figure 5 Schematic diagram of the second perspective when the wafer carrier stage of the present invention is connected to the sliding stage.

[0026] Figure 6 Schematic diagram of the position structure of multiple wafer carrier stages of the present invention.

[0027] Figure 7 Schematic diagram of the structure of the sliding stage after the wafer carrier stage and the sliding stage of the present invention are separated.

[0028] Figure 8 Schematic diagram of the second perspective structure of the sliding stage after the wafer carrier stage and the sliding stage of the present invention are separated.

[0029] Figure 9 Schematic diagram of the position structure of the material changing unit, storage rack and material changing rack of the present invention.

[0030] Figure 10 Schematic diagram of the movement directions of multiple wafer carrier stages of the present invention.

[0031] In the figure: 1. Sliding stage; 11. Support frame; 12. X-axis moving frame; 13. First driving rack; 14. Walking roller group; 15. Second driving gear; 16. Second driving motor; 17. Second guiding roller group; 2. Wafer carrier stage; 21. Connecting beam; 22. Y-axis moving frame; 23. Second driving rack; 3. First driving gear; 31. First driving motor; 4. Tabletop; 41. Guide track; 42. First guiding roller group; 5. Storage rack; 6. Material changing rack; 7. Material changing arm; 71. Electric rotating seat; 72. Cylinder; 8. Suction cup; 9. Bracket; 91. Driving projection; 92. Electric lead screw; 93. Limiting rod. Detailed implementation manners

[0032] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0033] Embodiment 1: Refer to Figure 1 、 Figure 10 A moving mechanism for a silicon wafer stage of a lithography machine, which includes two groups of silicon wafer carriers 2 that can reciprocate along a rectangular path. Each group consists of two laterally distributed silicon wafer carriers 2, and the four silicon wafer carriers 2 are arranged in a cross shape. In the initial state, the silicon wafer carrier 2 in the upper right corner among the four silicon wafer carriers 2 is directly opposite to the processing station of the lithography machine, and the processing station of the lithography machine is located at the exact center of the entire silicon wafer stage moving mechanism.

[0034] It also includes two loading and unloading units. The two loading and unloading units form two loading and unloading paths distributed from front to back with the processing station and a processing path located between the two loading and unloading paths. All three paths are laterally distributed. In the initial state, one of the two groups of silicon wafer carriers 2 is located on the processing path, and the other group is located on one of the loading and unloading paths.

[0035] When the silicon wafer stage moving mechanism operates for the first time, the two silicon wafer carriers 2 on the processing path are in a full-load state, and the two silicon wafer carriers 2 on the loading and unloading path are in an empty-load state. When the two groups of silicon wafer carriers 2 move simultaneously along the X-axis direction, the processing station can successively perform lithography processing operations on one of the groups of silicon wafer carriers 2. At this time, the loading and unloading units can perform loading operations on the two empty-load silicon wafer carriers 2, so that all four silicon wafer carriers 2 are in a full-load state.

[0036] When the four silicon wafer carriers 2 move towards the Y-axis, the two silicon wafer carriers 2 that have completed the loading and unloading operations move to the processing path, and the two processed silicon wafer carriers 2 move to the other loading and unloading path. The processing station can continue to perform processing operations on the silicon wafer carriers 2 on the processing path. After the processed silicon wafer carriers 2 move to the loading and unloading path, the loading and unloading units can take out the processed silicon wafers and replace them with raw silicon wafers to be processed.

[0037] When the four silicon wafer carriers 2 reciprocate along the rectangular path, there are always two silicon wafer carriers 2 on the processing path and the other two silicon wafer carriers 2 on the loading and unloading path among the four silicon wafer carriers 2. The processing station on the processing path can continuously perform processing operations on the silicon wafers in the silicon wafer carriers 2, and the loading and unloading path can continuously receive the processed silicon wafer carriers. As the silicon wafer carriers 2 reciprocate, the two loading and unloading units can take out the processed silicon wafers in turn and replace them with raw silicon wafers to be processed.

[0038] Therefore, when the entire wafer stage moving mechanism is operating, the processing station can continuously perform processing operations on the wafer stage 2. At the same time, the material changing unit can synchronously perform material changing operations on the wafer stage 2 after processing is completed, without affecting the implementation of the processing operations, and can quickly perform processing operations on multiple wafer raw materials, improving the working efficiency of the lithography machine for processing wafers.

[0039] Specifically, as Figures 2 - 8 shown, a slide table 1 and a table top 4 arranged in parallel with the slide table 1 are provided below the wafer stage 2. The bottom end of the slide table 1 is connected to an X-axis moving frame 12 through a support frame 11. The X-axis moving frame 12 has a U-shaped structure, and a first driving rack 13 arranged along the X direction is provided inside the X-axis moving frame 12.

[0040] A first driving gear 3 meshing with the first driving rack 13 and a first driving motor 31 capable of driving the first driving gear 3 to rotate are provided on the table top 4. Therefore, when the first driving motor 31 operates, the first driving gear 3 can be rotated, and during its rotation, the first driving rack 13 and the X-axis moving frame 12 meshing with it can be moved synchronously. When the X-axis moving frame 12, the support frame 11, and the slide table 1 move synchronously, the two wafer stages 2 move respectively within the material changing path and the processing path to achieve the purpose of enabling the wafer stage 2 to move along the X-axis path.

[0041] A traveling roller group 14 capable of moving synchronously with the slide table 1 is provided at the bottom end of the slide table 1. A guiding track 41 adapted to the traveling roller group 14 is provided on the table top 4, and a first guiding roller group 42 is provided on the table top 4. A channel through which the first guiding roller group 42 can pass is provided on the X-axis moving frame 12. The combined setting of the traveling roller 14, the guiding track 41, and the first guiding roller group 42 can improve the smoothness of the slide table 1 during movement, effectively avoiding shaking and offset phenomena of the slide table 1 and the wafer stage 2 during movement, and further ensuring the accuracy during the processing station and the material changing unit perform processing and material changing operations on the wafer stage 2.

[0042] Furthermore, a connecting beam 21 is provided below the wafer stage 2. A Y-axis moving frame 22 is provided on the connecting beam 21. The Y-axis moving frame 22 has a U-shaped structure, and a second driving rack 23 arranged along the Y-axis direction is provided inside the Y-axis moving frame 22.

[0043] A second driving gear 15 meshing with the second driving rack 23 and a second driving motor 16 capable of driving the second driving gear 15 to rotate are provided on the slide table 1. Therefore, when the second driving motor 16 operates, the second driving gear 15 can be made to mesh with the second driving rack 23 and move, and further the Y-axis moving frame 22 and the connecting beam 21 can be moved synchronously, causing the two wafer stages 2 to switch positions on the material changing path and the processing path.

[0044] In order to maintain the stability of the silicon wafer carrier 2 during movement, the slide 1 is provided with a second guide roller set 17 arranged along the Y-axis direction, and the connecting beam 21 and the Y-axis moving frame 22 are both provided with a channel that can accommodate the second guide roller set 17 to pass through.

[0045] Example 2: As Figure 9 As shown, on the basis of Example 1, in order to facilitate the material changing operation on the silicon wafer carrier 2, the material changing unit includes an L-shaped material changing arm 7, and the two vertically distributed arm bodies of the material changing arm 7 are provided with suction cups 8, and the two sides of the material changing arm 7 are provided with a storage rack 5 and a material changing rack 6 respectively. In the initial state, one arm body of the material changing arm 7 is located directly above the silicon wafer carrier 2, and the other arm body is located directly above the material changing rack 6. When the material changing arm 7 rotates, the two suction cups 8 can transfer the silicon wafers originally located in the material changing rack 6 to the inside of the silicon wafer carrier 2, and at the same time transfer the silicon wafers in the silicon wafer carrier 2 to the inside of the storage rack 5. Therefore, when the material changing arm 7 rotates, the unloading and loading operations can be carried out synchronously, which reduces the time required for repeated operation of silicon wafers and improves the efficiency of silicon wafer material changing and processing operations.

[0046] Specifically, in order to enable the material changing arm 7 to rotate smoothly, the material changing unit also includes an electric rotating seat 71 disposed at the bending position of the material changing arm 7. The electric rotating seat 71 is provided with a mounting plate located directly below the material changing arm 7, and a cylinder 72 is provided on the mounting plate. The push rod at the output end of the cylinder 72 is connected to the material changing arm 7. With the operation of the cylinder 72, the material changing arm 7 can be promoted to rise and fall, and then the suction cup 8 located directly above the silicon wafer carrier 2 and the material changing rack 6 can be synchronized. After the suction cup 8 descends and absorbs the silicon wafer, it can carry the silicon wafer and rise, so that the silicon wafer moves away from the original position and moves to the specified position.

[0047] It is worth mentioning that, in the initial state, a plurality of stacked silicon wafers to be processed are pre-stored inside the material changing rack 6, while the storage rack 5 is empty. As the entire silicon wafer table moving mechanism continues to operate, the number of processed silicon wafers inside the storage rack 5 continues to increase, while the number of silicon wafers inside the material changing rack 6 continues to decrease. Since the distance of the suction cup 8 rising and falling is limited, in order to avoid the suction cup 8 from failing to contact the silicon wafer inside the material changer 6 and the displacement phenomenon when the suction cup 8 drops the silicon wafer 8 into the storage rack 5, a bracket 9 capable of carrying silicon wafers is provided inside the storage rack 5 and the material changer 6, and a pair of driving protrusions 91 are provided on the bracket 9. A channel capable of accommodating the movement of the driving protrusions 91 is provided on the storage rack 5 and the material changer 6, and an electric screw 92 and a limit rod 93 are provided on the outer side of the storage rack 5 and the material changer 6, which are vertically distributed with the bracket 9. A pair of driving protrusions 91 are respectively installed on the electric screw 92 and the limit rod 93. When the driving protrusion 91 moves, the distance between the bracket 9 and the suction cup 8 above it can be adjusted.

[0048] During the process of the two suction cups 8 sucking out the silicon wafers inside the loading rack 6 and the silicon wafers falling into the storage rack 5 respectively, the bracket 9 can rise, and then the silicon wafers above it can be lifted to a specified height, prompting the silicon wafers to come into precise contact with the suction cups 8. At the same time, it can also precisely receive the falling silicon wafers to avoid collision when the silicon wafers fall.

[0049] With the multiple operations of the entire silicon wafer table moving mechanism, the number of processed silicon wafers inside the storage rack 5 increases continuously, while the number of silicon wafers inside the loading rack 6 decreases continuously. According to the thickness of the silicon wafers, the specifications of the suction cups 8, and the stroke of the lifting movement of the suction cups 8, settings can be made in advance in the PLC control system so that the stroke of each movement of the brackets 9 inside the storage rack 5 and the loading rack 6 is different, ensuring the smooth operation of the entire silicon wafer table moving mechanism.

[0050] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A photolithography machine silicon wafer stage moving mechanism, characterized in that: It comprises two groups of silicon wafer carriers (2) that can reciprocate along a rectangular path, each group is composed of two silicon wafer carriers (2) distributed laterally, and the four silicon wafer carriers (2) are arranged in a field shape. In an initial state, the silicon wafer carrier (2) located at the upper right corner of the four silicon wafer carriers (2) is directly opposite to the processing station of the photolithography machine; It also includes two material changing units, the two material changing units and the processing stations form two material changing paths distributed from front to back and a processing path located between the two material changing paths, and in an initial state, one of the two groups of silicon wafer carriers (2) is located on the processing path, and the other group is located on one of the material changing paths; When the two groups of silicon wafer carriers (2) move simultaneously along the X-axis direction, the processing station can sequentially perform photolithography processing operations on one group of silicon wafer carriers (2), and the material changing unit can sequentially perform material changing operations on the other group of silicon wafer carriers (2); when the four silicon wafer carriers (2) move toward the Y-axis, two silicon wafer carriers (2) that have completed the material changing operation move to the processing path, and two silicon wafer carriers (2) that have completed the processing move to another material changing path; when the four silicon wafer carriers (2) move back and forth along the rectangular path, two of the four silicon wafer carriers (2) are always located on the processing path, and the other two silicon wafer carriers (2) are located on the material changing path; The material changing unit comprises an L-shaped material changing arm (7), and suction cups (8) are provided on two vertically distributed arm bodies of the material changing arm (7), and a storage rack (5) and a material changing rack (6) are provided on both sides of the material changing arm (7), one arm body of the material changing arm (7) is located directly above the silicon wafer carrier (2), and the other arm body is located directly above the material changing rack (6), and when the material changing arm (7) rotates, the two suction cups (8) can transfer the silicon wafers originally located inside the material changing rack (6) to the inside of the silicon wafer carrier (2), and at the same time transfer the silicon wafers inside the silicon wafer carrier (2) to the inside of the storage rack (5); The material changing unit further comprises an electric rotating seat (71) arranged at the bending position of the material changing arm (7); a mounting plate located directly below the material changing arm (7) is provided on the electric rotating seat (71); a cylinder (72) is provided on the mounting plate; a push rod at the output end of the cylinder (72) is connected to the material changing arm (7); when the material changing arm (7) moves up and down, the suction cup (8) located directly above the silicon wafer carrier (2) and the material changing rack (6) moves synchronously until it contacts the silicon wafer.

2. The photolithography machine wafer stage moving mechanism according to claim 1, characterized in that: A slide table (1) and a table surface (4) arranged parallel to the slide table (1) are provided below the silicon wafer carrier (2); the bottom end of the slide table (1) is connected to an X-axis moving frame (12) via a support frame (11); the X-axis moving frame (12) is in a U-shaped structure, and a first driving rack (13) arranged along the X direction is provided on the inner side of the X-axis moving frame (12); The table top (4) is provided with a first driving gear (3) meshing with a first driving rack (13) and a first driving motor (31) capable of driving the first driving gear (3) to rotate. When the X-axis moving frame (12), the supporting frame (11) and the slide table (1) move synchronously, the two groups of silicon wafer carriers (2) are respectively located in the material replacement path and the processing path and move.

3. The photolithography machine wafer stage moving mechanism according to claim 2, characterized in that: The bottom end of the slide (1) is provided with a travel roller group (14) which can move synchronously therewith, the table top (4) is provided with a guide track (41) which is compatible with the travel roller group (14), and the table top (4) is provided with a first guide roller group (42), and the X-axis moving frame (12) is provided with a channel which can accommodate the first guide roller group (42) to pass through.

4. The photolithography machine wafer stage moving mechanism according to claim 2, characterized in that: A connecting beam (21) is provided below the silicon wafer carrier (2), a Y-axis moving frame (22) is provided on the connecting beam (21), the Y-axis moving frame (22) is in a U-shaped structure, and a second driving rack (23) arranged along the Y-axis direction is provided inside the Y-axis moving frame (22); The slide table (1) is provided with a second drive gear (15) meshing with a second drive rack (23) and a second drive motor (16) capable of driving the second drive gear (15) to rotate. When the Y-axis moving frame (22) and the connecting beam (21) move synchronously, the two sets of silicon wafer carriers (2) are located at switching positions on the material replacement path and the processing path.

5. The photolithography machine wafer stage moving mechanism according to claim 4, characterized in that: The slide table (1) is provided with a second guide roller group (17) arranged along the Y-axis direction, and the connecting beam (21) and the Y-axis moving frame (22) are both provided with a channel capable of accommodating the second guide roller group (17) to pass through.

6. The photolithography machine wafer stage moving mechanism according to claim 1, characterized in that: The storage rack (5) and the material changing rack (6) are both provided with a bracket (9) capable of carrying silicon wafers, and the bracket (9) is provided with a pair of driving protrusions (91). The storage rack (5) and the material changing rack (6) are both provided with a channel capable of accommodating the movement of the driving protrusions (91), and the outer sides of the storage rack (5) and the material changing rack (6) are both provided with an electric screw rod (92) and a limit rod (93) vertically distributed with respect to the bracket (9), and the pair of driving protrusions (91) are respectively installed on the electric screw rod (92) and the limit rod (93), and when the driving protrusions (91) move, the distance between the bracket (9) and the suction cup (8) above it can be adjusted.

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