A semiconductor wafer grabbing robot and grabbing method thereof

Abstract

The present invention belongs to the technical field of semiconductor equipment, and specifically is a semiconductor wafer grasping robot and grasping method thereof; it comprises a slide rail, a moving trolley is arranged inside the slide rail, a lifting hydraulic cylinder is arranged on the top of the moving trolley, a first motor is arranged on the top of the lifting hydraulic cylinder, a first bracket is arranged on the output end of the first motor, a pair of first hydraulic cylinders are arranged on the top of the first bracket; a connecting piece is arranged on the output end of the first hydraulic cylinder; the semiconductor wafer grasping robot and grasping method thereof described in the present invention, by arranging a rotating ball and an air bag, when grasping the wafer, the air bag cooperates with a pressure sensor to detect whether the wafer is tilted, and the angle of the receiving plate is adjusted by the second hydraulic cylinder and a pressure rod; after adjustment, the wafer remains horizontal, and then the wafer transfer is controlled. During the transfer process, the wafer remains horizontal, and the surface of the wafer is subjected to less wind resistance, which is beneficial to the protection of the wafer.

Description

Technical Field

[0001] The invention belongs to the technical field of semiconductor equipment, in particular to a semiconductor wafer grabbing robot and a grabbing method thereof. Background Art

[0002] A wafer refers to a silicon chip used in the manufacture of silicon semiconductor integrated circuits. Due to its round shape, it is called a silicon wafer. In the semiconductor manufacturing process, wafers need to be transported; for example, wafers need to be transported and transferred between etchers, photolithography machines, thin film deposition equipment, wafer cleaning equipment, etc. Currently, they are grabbed and transported by robots.

[0003] Currently, when a robot grabs a wafer, a suction cup is set at the end of the robot. When grabbing the wafer, the suction cup absorbs and fixes the wafer, and then releases it when the suction cup carries the wafer to a specified position. In the process of transferring the wafer, the wafer needs to be kept horizontal to prevent the surface of the wafer from tilting during the transfer and being subject to large wind resistance. Since semiconductor wafers are usually made of brittle materials such as silicon, these materials themselves have low tensile strength and high brittleness and are prone to breakage. Therefore, the wafer surface is prone to breakage and damage when subject to large wind resistance. After the existing robot grabs the wafer through the suction cup, the suction cup may not be adsorbed at the center of the wafer, so the pulling force at different positions of the suction cup is different, and the suction cup will produce a slight deformation, causing the wafer to tilt; it is not conducive to the protection of the wafer during the transfer process.

[0004] To this end, the present invention provides a semiconductor wafer grasping robot and a grasping method thereof. Summary of the invention

[0005] In order to make up for the deficiencies of the prior art, at least one technical problem raised in the background technology is solved.

[0006] The technical solution adopted by the present invention to solve its technical problems is as follows: a semiconductor wafer grabbing robot described in the present invention comprises a slide rail, a moving trolley is arranged inside the slide rail, a lifting hydraulic cylinder is arranged on the top of the moving trolley, a first motor is arranged on the top of the lifting hydraulic cylinder, a first bracket is arranged on the output end of the first motor, and a pair of first hydraulic cylinders are arranged on the top of the first bracket; a connecting piece is arranged on the output end of the first hydraulic cylinder; a receiving frame is arranged on the end of the connecting piece away from the first hydraulic cylinder, a fixed frame is arranged on the end of the receiving frame away from the connecting piece, a rotating ball is arranged below the fixed frame, a receiving plate is fixedly connected to the bottom end of the rotating ball, a vacuum suction cup is arranged on the bottom end of the receiving plate, a pair of brake blocks are arranged on both ends of the rotating ball, a side of the brake block facing the rotating ball is arranged as a concave surface, and is adapted to the surface of the rotating ball; an extrusion assembly is arranged between the brake block and the fixed frame;

[0007] The bottom end of the receiving frame is provided with a plurality of positioning plates in a ring shape, the bottom end of the positioning plate is provided with a second hydraulic cylinder, and the output end of the second hydraulic cylinder is provided with a pressure rod; initially, the bottom end of the pressure rod is not in contact with the receiving plate; the top end of the receiving plate is provided with a plurality of fixing plates, the bottom end of the fixing plate outside the receiving plate is provided with a pressure sensor, the pressure-bearing end of the pressure sensor is provided with a connecting rod, and the bottom end of the connecting rod is provided with an airbag.

[0008] Preferably, a first pump body is disposed at the top end of the fixing plate, and a first hose is connected to the output end of the first pump body, and the first hose is connected to the airbag.

[0009] Preferably, the extrusion assembly includes a cylinder, a piston is slidably connected to the inside of the cylinder, and the end of the piston outside the cylinder is connected to the side of the brake pad; the cylinder is fixed to the side of the fixed frame; a second hose is connected to the side of the cylinder, and a first valve is provided at the end of the second hose away from the cylinder; a pressure warning device is provided inside the cylinder.

[0010] Preferably, a third hose is provided on the surface of the second hose, and a second valve is provided on one end of the third hose away from the second hose. The second valve is specifically a pressure relief valve.

[0011] Preferably, the connecting member is specifically a servo motor; the housing portion of the servo motor is installed at the output end of the first hydraulic cylinder; and the output end of the servo motor is connected to the end of the receiving frame.

[0012] Preferably, a pair of second brackets are arranged at the top of the first bracket, a pair of third hydraulic cylinders are arranged at the top of the second bracket, and a windshield is arranged at the output end of the third hydraulic cylinder. When the servo motor is started, the third hydraulic cylinder drives the windshield to move to the positions on both sides of the wafer adsorbed by the vacuum suction cup.

[0013] Preferably, a receiving groove is provided on the side of the windshield away from the third hydraulic cylinder, a folding plate is provided inside the receiving groove, and a magnetic strip is provided at one end of the folding plate outside the receiving groove; an electromagnet is provided at the end of the windshield away from the magnetic strip.

[0014] Preferably, the folding plate is made of rigid plastic.

[0015] A semiconductor wafer grabbing method comprises the following steps:

[0016] S1. When in use, the mobile trolley moves inside the slide rail as needed, cooperates with the lifting hydraulic cylinder to drive the first bracket to move up and down, and at the same time, the first motor drives the first bracket to rotate to the required position;

[0017] S2. When grabbing the wafer, the receiving plate is controlled to move downward, and stops when the vacuum suction cup at the bottom of the receiving plate contacts the surface of the wafer, and then the wafer is adsorbed by the vacuum suction cup;

[0018] S3, then controlling the wafer to move upward and away from the support;

[0019] S4. When the wafer is transferred to the designated position, the vacuum chuck is removed from adsorbing the wafer; the wafer grabbing and transfer is completed.

[0020] Preferably, when the vacuum suction cup adsorbs the wafer, it is necessary to control the bottom end of the vacuum suction cup to adhere to the top surface of the wafer and generate a certain squeezing force to ensure that the opening of the vacuum suction cup is sealed by the wafer.

[0021] The beneficial effects of the present invention are as follows:

[0022] 1. A semiconductor wafer grabbing robot and a grabbing method thereof described in the present invention, by setting a rotating ball and an airbag, when grabbing the wafer, the airbag cooperates with a pressure sensor to detect whether the wafer is tilted, and the second hydraulic cylinder cooperates with a pressure rod to adjust the angle of the receiving plate; after adjustment, the wafer remains horizontal, and then the wafer transfer is controlled. During the transfer process, the wafer remains horizontal, and the surface of the wafer is subject to less wind resistance, which is beneficial to the protection of the wafer.

[0023] 2. The semiconductor wafer grasping robot and grasping method described in the present invention are provided with a servo motor; the output end of the servo motor is connected to the end of the receiving frame; when transferring the wafer, there is a situation where the wafer needs to be turned over, so a servo motor is provided, and the servo motor drives the receiving frame to rotate one hundred and eighty degrees; then another robot can grasp the transferred and turned wafer, thereby improving the flexibility of use. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The present invention will be further described below in conjunction with the accompanying drawings.

[0025] Figure 1 is a stereogram of the present invention;

[0026] Figure 2 It is a schematic diagram of the structure on the slide rail of the present invention;

[0027] Figure 3 It is a schematic diagram of the structure on the first bracket of the present invention;

[0028] Figure 4 It is a structural schematic diagram of the receiving plate of the present invention;

[0029] Figure 5 It is a schematic diagram of the structure on the fixing frame of the present invention;

[0030] Figure 6 It is a schematic diagram of the cylinder connection structure of the present invention;

[0031] Figure 7 It is a schematic diagram of the connection structure of the receiving frame of the present invention;

[0032] Figure 8 It is a schematic diagram of the fixing plate connection structure of the present invention;

[0033] Fig. 9 is a schematic diagram of a windshield of the present invention;

[0034] Fig.10 is a schematic diagram of a folding plate of the present invention;

[0035] Fig.11 It is a schematic flow chart of the method of the present invention.

[0036] In the figure: 1. slide rail; 11. moving trolley; 12. lifting hydraulic cylinder; 13. first motor; 2. first bracket; 3. second bracket; 4. first hydraulic cylinder; 41. connecting piece; 42. receiving frame; 43. fixed frame; 5. receiving plate; 50. vacuum suction cup; 51. rotating ball; 52. brake block; 53. cylinder; 54. piston; 55. second hose; 56. first valve; 57. third hose; 58. second valve; 6. positioning plate; 61. second hydraulic cylinder; 62. pressure rod; 7. fixed plate; 71. pressure sensor; 72. connecting rod; 73. air bag; 74. first hose; 75. first pump body; 8. third hydraulic cylinder; 81. wind shield; 82. receiving groove; 83. folding plate; 84. magnetic strip; 85. electromagnet. DETAILED DESCRIPTION

[0037] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further explained below in conjunction with specific implementation methods.

[0038] like Figures 1 to 8 As shown, a semiconductor wafer grabbing robot according to an embodiment of the present invention comprises a slide rail 1, a moving trolley 11 is arranged inside the slide rail 1, a lifting hydraulic cylinder 12 is arranged at the top of the moving trolley 11, a first motor 13 is arranged at the top of the lifting hydraulic cylinder 12, a first bracket 2 is arranged at the output end of the first motor 13, a pair of first hydraulic cylinders 4 are arranged at the top of the first bracket 2; a connecting member 41 is arranged at the output end of the first hydraulic cylinder 4; a receiving frame 42 is arranged at the end of the connecting member 41 away from the first hydraulic cylinder 4, a fixed frame 43 is arranged at one end of the receiving frame 42 away from the connecting member 41, a rotating ball 51 is arranged below the fixed frame 43, a receiving plate 5 is fixedly connected to the bottom end of the rotating ball 51, a vacuum suction cup 50 is arranged at the bottom end of the receiving plate 5, a pair of brake blocks 52 are arranged at both ends of the rotating ball 51, a side of the brake block 52 facing the rotating ball 51 is arranged as a concave surface, and is adapted to the surface of the rotating ball 51; an extrusion assembly is arranged between the brake block 52 and the fixed frame 43;

[0039] The bottom end of the receiving frame 42 is provided with a plurality of positioning plates 6 in a ring shape, the bottom end of the positioning plate 6 is provided with a second hydraulic cylinder 61, and the output end of the second hydraulic cylinder 61 is provided with a pressure rod 62; initially, the bottom end of the pressure rod 62 is not in contact with the receiving plate 5; the top end of the receiving plate 5 is provided with a plurality of fixing plates 7, the bottom end of the fixing plate 7 outside the receiving plate 5 is provided with a pressure sensor 71, the pressure end of the pressure sensor 71 is provided with a connecting rod 72, and the bottom end of the connecting rod 72 is provided with an air bag 73;

[0040] When grabbing and transferring the wafer, the wafer needs to be kept horizontal to prevent the wafer surface from tilting during the transfer process and being subject to large wind resistance. Since semiconductor wafers are usually made of brittle materials such as silicon, these materials themselves have low tensile strength and high brittleness, and are prone to breakage; therefore, the wafer surface is prone to breakage and damage when subject to large wind resistance; after the existing manipulator grabs the wafer through the suction cup, the suction cup may not be attached to the center of the wafer, so the pulling force at different positions of the suction cup is different, and then the suction cup will produce slight deformation, causing the wafer to tilt; It is beneficial to protect the wafer during the transfer process; to solve the above problems, the embodiment of the present invention is provided with structures such as a rotating ball 51 and an air bag 73; the specific use process is as follows: when in use, the mobile trolley 11 will move inside the slide rail 1 as needed, and cooperate with the lifting hydraulic cylinder 12 to drive the first bracket 2 to move up and down, and at the same time, the first motor 13 drives the first bracket 2 to rotate to the required position. When grabbing the wafer, the receiving plate 5 is controlled to move downward, and the vacuum suction cup 50 at the bottom of the receiving plate 5 stops when it contacts the surface of the wafer bar, and then the vacuum suction cup 50 is used to move the wafer. The wafer is adsorbed; then the wafer is controlled to move upward and leave the support; when the wafer is adsorbed and fixed, the airbag 73 is squeezed by the surface of the wafer. When the wafer is tilted, the airbags 73 at different positions are squeezed to different degrees. Therefore, different airbags 73 exert different squeezing forces on the pressure-receiving end of the pressure sensor 71 through the connecting rod 72. The pressure sensor 71 is connected to an external computer through an electrical signal. After receiving the signal from the pressure sensor 71, the computer controls the output of different second hydraulic cylinders 61, so that the second hydraulic cylinder 61 drives the pressure rod 62 to squeeze the receiving end. The top of the plate 5 makes the receiving plate 5 adjust its angle based on the rotating ball 51. Specifically, when the angle of the receiving plate 5 changes, the rotating ball 51 rotates relative to the brake block 52, and the angle of the receiving plate 5 is stabilized by the friction between the rotating ball 51 and the brake block 52. When adjusting, the control stops when the data of the pressure sensors 71 at different positions are the same, that is, the squeezing force of the wafer on different airbags 73 is the same; therefore, the wafer remains horizontal after adjustment, and then the wafer transfer is controlled. During the transfer process, the wafer remains horizontal, and the surface of the wafer is subject to less wind resistance, which is beneficial to the protection of the wafer.

[0041] A first pump body 75 is provided at the top of the fixing plate 7, and a first hose 74 is connected to the output end of the first pump body 75, and the first hose 74 is connected to the airbag 73; after adjusting the wafer to keep it horizontal, the first pump body 75 draws air inside the airbag 73 through the first hose 74, so that the airbag 73 no longer expands, and further no longer squeezes the surface of the wafer, thereby avoiding continuous squeezing and damage to the wafer surface.

[0042] The extrusion assembly includes a cylinder 53, the interior of the cylinder 53 is slidably connected with a piston 54, and one end of the piston 54 outside the cylinder 53 is connected to the side of the brake block 52; the cylinder 53 is fixed to the side of the fixing frame 43; the side of the cylinder 53 is connected with a second hose 55, and the end of the second hose 55 away from the cylinder 53 is provided with a first valve 56; the interior of the cylinder 53 is provided with a pressure warning device; after long-term use of the rotating ball 51, the surfaces of the rotating ball 51 and the brake block 52 may be worn, resulting in the extrusion force between the rotating ball 51 and the brake block 52 Reduced; which leads to reduced angular stability of the receiving plate 5; therefore, a cylinder 53 is provided, and when the surfaces of the rotating ball 51 and the brake block 52 are worn, the squeezing pressure of the piston 54 on the gas in the cylinder 53 is reduced, and the pressure warning device in the cylinder 53 sends a warning electrical signal to the external computer to remind the staff to deal with it; the staff inflates the cylinder 53 through the first valve 56 and the second hose 55, and the gas pressure in the cylinder 53 increases, causing the squeezing pressure of the piston 54 on the rotating ball 51 to be restored; thereby ensuring that the friction between the rotating ball 51 and the brake block 52 meets the use requirements.

[0043] A third hose 57 is provided on the surface of the second hose 55, and a second valve 58 is provided at one end of the third hose 57 away from the second hose 55. The second valve 58 is specifically a pressure relief valve. When the cylinder 53 is inflated, when the gas pressure in the cylinder 53 reaches the specified requirement, the cylinder 53 will continue to be inflated and the gas will be automatically discharged through the second valve 58 connected to the third hose 57, thereby avoiding excessive air pressure inside the cylinder 53, which would cause excessive friction between the rotating ball 51 and the brake block 52 and affect its use.

[0044] The connecting part 41 is specifically a servo motor; the shell part of the servo motor is installed at the output end of the first hydraulic cylinder 4; the output end of the servo motor is connected to the end of the receiving frame 42; when transferring the wafer, there is a situation where the wafer needs to be turned over, so a servo motor is provided, and the servo motor drives the receiving frame 42 to rotate one hundred and eighty degrees; then another robot can grab the transferred and turned wafer, thereby improving the flexibility of use.

[0045] like Figures 1 to 10As shown, a pair of second brackets 3 are arranged at the top of the first bracket 2, a pair of third hydraulic cylinders 8 are arranged at the top of the second bracket 3, and a windshield 81 is arranged at the output end of the third hydraulic cylinder 8. When the servo motor is started, the third hydraulic cylinder 8 drives the windshield 81 to move to the positions on both sides of the wafer adsorbed by the vacuum suction cup 50; when controlling the wafer to flip, in order to improve the wafer transfer efficiency, the wafer keeps moving; at this time, the windshield 81 is driven to both sides of the wafer, so when the wafer is turned over, the windshield 81 will block the wind for the wafer to avoid the surface of the wafer being damaged by excessive wind resistance when the wafer is turned over.

[0046] A receiving groove 82 is provided on the side of the wind shield 81 away from the third hydraulic cylinder 8, and a folding plate 83 is provided inside the receiving groove 82, and a magnetic strip 84 is provided on the end of the folding plate 83 outside the receiving groove 82; an electromagnet 85 is provided at the end of the wind shield 81 away from the magnetic strip 84; when the wind shield 81 is controlled to block the wind for the wafer, the electromagnet 85 is energized, and the electromagnet 85 and the magnetic strip 84 generate a repulsive magnetic force, so that the magnetic strip 84 drives the folding plate 83 to extend, and then the folding plate 83 blocks the airflow on both sides of the wafer to achieve a wind shielding effect; it is reset after the wafer is turned over; the volume of the wind shield 81 can be reduced to avoid the wind shield 81 interfering with the transfer of the wafer.

[0047] The folding plate 83 is made of rigid plastic to ensure the use strength of the folding plate 83 and prevent the folding plate 83 from bending and contacting the wafer when stretched under the action of wind.

[0048] like Fig.11 As shown, a semiconductor wafer grabbing method comprises the following steps:

[0049] S1. When in use, the mobile trolley 11 moves inside the slide rail 1 as needed, and cooperates with the lifting hydraulic cylinder 12 to drive the first bracket 2 to move up and down, while the first motor 13 drives the first bracket 2 to rotate to the required position;

[0050] S2, when grabbing the wafer, control the receiving plate 5 to move downward, and stop when the vacuum suction cup 50 at the bottom of the receiving plate 5 contacts the surface of the wafer, and then adsorb the wafer by the vacuum suction cup 50;

[0051] S3, then controlling the wafer to move upward and away from the support;

[0052] S4. When the wafer is transferred to the designated position, the vacuum chuck 50 is removed from adsorbing the wafer; the wafer grabbing and transfer is completed.

[0053] The above shows and describes the basic principles, main features and advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A semiconductor wafer grabbing robot, characterized in that: The invention comprises a slide rail (1), wherein a moving trolley (11) is arranged inside the slide rail (1), a lifting hydraulic cylinder (12) is arranged at the top of the moving trolley (11), a first motor (13) is arranged at the top of the lifting hydraulic cylinder (12), a first bracket (2) is arranged at the output end of the first motor (13), a pair of first hydraulic cylinders (4) are arranged at the top of the first bracket (2); a connecting member (41) is arranged at the output end of the first hydraulic cylinder (4); a receiving frame (42) is arranged at the end of the connecting member (41) away from the first hydraulic cylinder (4), A fixing frame (43) is provided at one end of the receiving frame (42) away from the connecting member (41); a rotating ball (51) is provided below the fixing frame (43); a receiving plate (5) is fixedly connected to the bottom end of the rotating ball (51); a vacuum suction cup (50) is provided at the bottom end of the receiving plate (5); a pair of brake blocks (52) are provided at both ends of the rotating ball (51); a side of the brake block (52) facing the rotating ball (51) is configured as a concave surface and is adapted to the surface of the rotating ball (51); an extrusion assembly is provided between the brake block (52) and the fixing frame (43); The bottom end of the receiving frame (42) is provided with a plurality of positioning plates (6) in a ring shape, the bottom end of the positioning plate (6) is provided with a second hydraulic cylinder (61), and the output end of the second hydraulic cylinder (61) is provided with a pressure rod (62); initially, the bottom end of the pressure rod (62) is not in contact with the receiving plate (5); the top end of the receiving plate (5) is provided with a plurality of fixing plates (7), the bottom end of the fixing plate (7) outside the receiving plate (5) is provided with a pressure sensor (71), the pressure-bearing end of the pressure sensor (71) is provided with a connecting rod (72), and the bottom end of the connecting rod (72) is provided with an air bag (73).

2. A semiconductor wafer grabbing robot according to claim 1, characterized in that: A first pump body (75) is disposed at the top end of the fixing plate (7), and a first hose (74) is disposed at the output end of the first pump body (75), and the first hose (74) is in communication with the air bag (73).

3. A semiconductor wafer grabbing robot according to claim 1, characterized in that: The extrusion assembly comprises a cylinder (53), the interior of the cylinder (53) being slidably connected to a piston (54), one end of the piston (54) located outside the cylinder (53) being connected to a side surface of a brake block (52); the cylinder (53) being fixed to a side surface of a fixing frame (43); a second hose (55) being connected to the side surface of the cylinder (53), a first valve (56) being provided at one end of the second hose (55) away from the cylinder (53); and a pressure warning device being provided inside the cylinder (53).

4. A semiconductor wafer grabbing robot according to claim 3, characterized in that: The surface of the second hose (55) is connected to a third hose (57), and one end of the third hose (57) away from the second hose (55) is connected to a second valve (58), wherein the second valve (58) is specifically a pressure relief valve.

5. A semiconductor wafer grabbing robot according to claim 1, characterized in that: The connecting member (41) is specifically a servo motor; the housing portion of the servo motor is mounted on the output end of the first hydraulic cylinder (4); and the output end of the servo motor is connected to the end of the receiving frame (42).

6. A semiconductor wafer grabbing robot according to claim 5, characterized in that: A pair of second supports (3) are arranged at the top of the first support (2), a pair of third hydraulic cylinders (8) are arranged at the top of the second support (3), and a windshield (81) is arranged at the output end of the third hydraulic cylinder (8). When the servo motor is started, the third hydraulic cylinder (8) drives the windshield (81) to move to the positions on both sides of the wafer adsorbed by the vacuum suction cup (50).

7. A semiconductor wafer grabbing robot according to claim 6, characterized in that: A receiving groove (82) is provided on a side of the windshield plate (81) away from the third hydraulic cylinder (8); a folding plate (83) is provided inside the receiving groove (82); a magnetic strip (84) is provided at one end of the folding plate (83) located outside the receiving groove (82); and an electromagnet (85) is provided at the end of the windshield plate (81) away from the magnetic strip (84).

8. A semiconductor wafer grabbing robot according to claim 7, characterized in that: The folding plate (83) is made of rigid plastic.

9. A semiconductor wafer grasping method, the method using a semiconductor wafer grasping robot as described in any one of claims 1 to 8, characterized in that: The following steps are involved: S1. When in use, the mobile trolley (11) moves inside the slide rail (1) as required, cooperates with the lifting hydraulic cylinder (12) to drive the first bracket (2) to move up and down, and at the same time, the first motor (13) drives the first bracket (2) to rotate to a required position; S2, when grabbing the wafer, controlling the receiving plate (5) to move downward, stopping when the vacuum suction cup (50) at the bottom of the receiving plate (5) contacts the surface of the wafer, and then adsorbing the wafer through the vacuum suction cup (50); S3, then controlling the wafer to move upward and away from the support; S4, when the wafer is transferred to the designated position, canceling the suction of the vacuum suction cup (50) on the wafer; Wafer grab transfer is completed.

10. A semiconductor wafer grabbing method according to claim 9, characterized in that: When the vacuum suction cup (50) adsorbs the wafer, it is necessary to control the bottom end of the vacuum suction cup (50) to adhere to the top surface of the wafer and generate a certain squeezing force to ensure that the opening of the vacuum suction cup (50) is sealed by the wafer.

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