Wafer alignment apparatus and method of alignment

Abstract

The application provides a wafer alignment device and an alignment method thereof. The wafer alignment device comprises a workbench, an upper wafer movement system comprising an upper wafer carrier plate for carrying an upper wafer, a lower wafer movement system comprising a lower wafer carrier plate for carrying a lower wafer, and a first visual detection system arranged above the upper wafer movement system. The first visual detection system comprises a Y-axis movement assembly, a Z-axis movement assembly and a visual device, the Y-axis movement assembly is capable of driving the visual device to move along a Y-axis direction, and the Z-axis movement assembly is capable of driving the visual device to move along a Z-axis direction. The wafer alignment device further comprises a first mounting frame arranged on the workbench, the first mounting frame comprising a first cross beam extending along an X-axis direction. The Y-axis movement assembly comprises a movable assembly and a gas foot assembly, the movable assembly is sleeved on the first cross beam and is capable of moving along the first cross beam, and the movable assembly is in gas floating cooperation with the first cross beam through the gas foot assembly.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor manufacturing equipment, in particular to a wafer alignment device and an alignment method thereof. BACKGROUND

[0002] In the manufacturing process of semiconductor devices, wafer bonding is a key step to realize advanced packaging technologies such as three-dimensional integration and heterogeneous integration, and wafer alignment device is a core equipment to ensure bonding accuracy and improve device performance and yield. Precise wafer alignment can effectively reduce the alignment error after bonding, thereby improving the quality and consistency of the final product.

[0003] When aligning the upper wafer and the lower wafer, it is necessary to control the movement of the vision device and position it at a predetermined position to detect the alignment marks on the wafer surface, thereby providing a basis for wafer alignment. Therefore, the stability of the movement of the vision device and the accuracy of the positioning have an important influence on the precision of wafer alignment. The existing wafer alignment device usually sets the vision device on the mounting frame, and supports and guides the movement of the vision device through the mounting frame. In the process of moving the vision device to the detection position by the motion assembly of the wafer alignment device along the mounting frame, the motion assembly and the mounting frame are in contact with each other, and the mounting frame usually has machining and installation errors. Therefore, the motion state of the motion assembly is affected by the machining and installation errors of the mounting frame, resulting in poor movement stability of the vision device driven by the motion assembly, and the vision device cannot accurately move and position to the predetermined position, thereby affecting the precision of wafer alignment and reducing the production efficiency and yield of wafer bonding. SUMMARY

[0004] The main purpose of the present application is to provide a wafer alignment device and an alignment method thereof, which can solve the problem that the motion assembly of the existing wafer alignment device is easily affected by the machining and installation errors of the mounting frame during movement along the mounting frame, resulting in the vision device cannot accurately move and position to the predetermined position, and reducing the precision of wafer alignment.

[0005] In order to achieve the above object, according to an aspect of the present application, a wafer alignment device is provided, comprising a worktable; an upper wafer movement system comprising an upper wafer carrier plate for carrying an upper wafer; a lower wafer movement system comprising a lower wafer carrier plate for carrying a lower wafer; further comprising: a first vision detection system arranged above the upper wafer movement system; the first vision detection system comprising: a Y-axis movement assembly, a Z-axis movement assembly, and a vision device, the Y-axis movement assembly being capable of moving the vision device along a Y-axis direction, the Z-axis movement assembly being capable of moving the vision device along a Z-axis direction; a first mounting frame arranged on the worktable, the first mounting frame comprising a first cross beam extending along an X-axis direction; the Y-axis movement assembly comprising: a movable assembly, the movable assembly being sleeved on the first cross beam and being capable of moving along the first cross beam; and a gas foot assembly, the movable assembly being in gas floating cooperation with the first cross beam through the gas foot assembly.

[0006] Further, the movable assembly comprises a top plate arranged above the first cross beam; the gas foot assembly comprises a first vacuum part arranged on the top plate or the first cross beam, the first vacuum part being capable of generating negative pressure to adsorb and fix the top plate on the first cross beam.

[0007] Further, the movable assembly comprises a bottom plate arranged below the first cross beam, the gas foot assembly comprising: a first gas floating pad and a first pre-tightening member in driving connection, the first gas floating pad being arranged on one of the bottom plate and the first cross beam, the first pre-tightening member being capable of driving the first gas floating pad to move up / down to provide a force capable of tightly pressing the other one of the bottom plate and the first cross beam.

[0008] Further, the gas foot assembly comprises: a second gas floating pad and a second pre-tightening member in driving connection, the second gas floating pad being arranged on one of the top plate and the first cross beam, the second pre-tightening member being capable of driving the second gas floating pad to move up / down to provide a force capable of tightly pressing the other one of the top plate and the first cross beam.

[0009] Further, the movable assembly comprises a top plate arranged above the first cross beam and a bottom plate arranged below the first cross beam, the gas foot assembly further comprising a first positive pressure part and a second positive pressure part; the first positive pressure part being arranged on the top plate or the first cross beam, the second positive pressure part being arranged on the bottom plate or the first cross beam, the first positive pressure part and the second positive pressure part being capable of making the movable assembly gas-suspended on the first cross beam.

[0010] Further, the movable assembly comprises a first side plate and a second side plate arranged on both sides of the first cross beam, an outer side of the first side plate being provided with the Z-axis movement assembly, and an outer side of the second side plate being provided with a counterweight.

[0011] Further, the Y-axis movement assembly comprises a first guide rail part and a first driving part, the first guide rail part is arranged on the first mounting frame and extends along the Y-axis direction, the movable assembly is in sliding fit with the first guide rail part, and the first driving part is capable of driving the movable assembly to slide along the first guide rail part.

[0012] Further, along the X-axis direction, the first guide rail part comprises a first inner side surface facing a side surface of the top plate of the movable assembly, the air foot assembly further comprises a third air cushion and a third pre-tightening part in driving connection, the third air cushion is arranged on one of the first inner side surface and the movable assembly, and the third pre-tightening part is capable of driving the third air cushion to move so as to provide a force capable of tightly pressing the other one of the first inner side surface and the movable assembly for the third air cushion.

[0013] Further, along the X-axis direction, the first guide rail part comprises a second inner side surface opposite to the first inner side surface, and the air foot assembly further comprises a third positive pressure part arranged on the second inner side surface or the movable assembly, the third positive pressure part and the third air cushion cooperate to provide a guide for movement of the movable assembly in the Y-axis direction.

[0014] Further, along the X-axis direction, the first guide rail part further comprises a second inner side surface opposite to the first inner side surface, and the air foot assembly further comprises a third vacuum part arranged on the second inner side surface or the movable assembly, the third vacuum part is capable of generating a negative pressure to adsorb and fix the first guide rail part on the movable assembly.

[0015] Further, a groove extending along the Y-axis direction is arranged on the top plate of the movable assembly; along the X-axis direction, the groove comprises a third inner side surface and a fourth inner side surface; along the X-axis direction, the first guide rail part comprises a first outer side surface facing the third inner side surface, and the air foot assembly further comprises a fourth air cushion and a fourth pre-tightening part in driving connection, the fourth air cushion is arranged on one of the third inner side surface and the first outer side surface, and the fourth pre-tightening part is capable of driving the fourth air cushion to move so as to provide a force capable of tightly pressing the other one of the third inner side surface and the first outer side surface for the fourth air cushion.

[0016] Further, along the X-axis direction, the first guide rail part further comprises a second outer side surface opposite to the first outer side surface, the second outer side surface faces the fourth inner side surface; the air foot assembly further comprises a fourth positive pressure part arranged on the second outer side surface or the fourth inner side surface, and the fourth positive pressure part is capable of cooperating with the fourth air cushion to provide a guide for movement of the movable assembly in the Y-axis direction.

[0017] Further, along the X-axis direction, the first guide rail part further comprises a second outer side surface opposite to the first outer side surface, the second outer side surface faces the fourth inner side surface; the air foot assembly further comprises a second vacuum part arranged on the second outer side surface or the fourth inner side surface, and the second vacuum part is capable of generating a negative pressure to adsorb and fix the first guide rail part on the movable assembly.

[0018] Further, the first visual inspection system further comprises an X-axis movement assembly, the X-axis movement assembly comprising an X-axis guide rail portion and a second driving portion, the X-axis guide rail portion being arranged on the first mounting frame and extending along the X-axis direction, the second driving portion comprising a first stator portion and a first mover portion, the first stator portion being arranged on the first mounting frame and drivingly connected with the first mover portion, the first mover portion being slidingly fitted with the X-axis guide rail portion; the movable assembly being arranged on the first mover portion, the first mover portion being capable of driving the movable assembly to move along the first cross beam in the X-axis direction.

[0019] Further, the first guide rail portion is connected with the first mover portion and arranged on the movable assembly.

[0020] Further, the Y-axis movement assembly comprises a first driving portion, the first driving portion comprising a second stator portion and a second mover portion, the second stator portion being arranged on the first guide rail portion, the second mover portion being arranged on the top plate above the first cross beam, the second stator portion drivingly fitted with the second mover portion.

[0021] Further, the wafer alignment device further comprises a second visual inspection system, the second visual inspection system being arranged corresponding to the first visual inspection system in the Z-axis direction and below the lower wafer movement system.

[0022] Further, the upper wafer carrier plate is provided with a detection hole, the first visual inspection system being capable of detecting the alignment mark of the lower wafer on the lower wafer carrier plate through the detection hole.

[0023] Further, corresponding to the upper wafer, a first detection position and a first wafer loading position are arranged; the upper wafer is loaded onto the upper wafer carrier plate at the first wafer loading position, and the upper wafer is subjected to alignment mark detection at the first detection position; corresponding to the lower wafer, a second detection position and a second wafer loading position are arranged; the lower wafer is loaded onto the lower wafer carrier plate at the second wafer loading position, and the lower wafer is subjected to alignment mark detection at the second detection position; when the upper wafer is at the first wafer loading position, the center line of the upper wafer along the Z-axis direction is a first Z-axis center line; when the upper wafer is at the first detection position, the center line of the upper wafer along the Z-axis direction is a second Z-axis center line; when the lower wafer is at the second wafer loading position, the center line of the lower wafer along the Z-axis direction is a third Z-axis center line; when the lower wafer is at the second detection position, the center line of the lower wafer along the Z-axis direction is a fourth Z-axis center line; the first Z-axis center line, the second Z-axis center line, the third Z-axis center line and the fourth Z-axis center line coincide.

[0024] According to another aspect of the present application, there is also provided an alignment method for aligning an upper wafer and a lower wafer based on the wafer alignment device described above, comprising: corresponding to the upper wafer, setting a first detection position and a first wafer loading position; loading the upper wafer to an upper wafer loading plate at the first wafer loading position, and detecting alignment marks at the first detection position; corresponding to the lower wafer, setting a second detection position and a second wafer loading position; loading the lower wafer to a lower wafer loading plate at the second wafer loading position, and detecting alignment marks at the second detection position; when the upper wafer is at the first wafer loading position, the center line of the upper wafer along the Z-axis direction is a first Z-direction center line; when the upper wafer is at the first detection position, the center line of the upper wafer along the Z-axis direction is a second Z-direction center line; when the lower wafer is at the second wafer loading position, the center line of the lower wafer along the Z-axis direction is a third Z-direction center line; when the lower wafer is at the second detection position, the center line of the lower wafer along the Z-axis direction is a fourth Z-direction center line; the first Z-direction center line, the second Z-direction center line, the third Z-direction center line and the fourth Z-direction center line coincide; loading the upper wafer and the lower wafer to the upper wafer loading plate and the lower wafer loading plate respectively; and detecting alignment marks of the upper wafer and the lower wafer by the first visual detection system respectively.

[0025] According to another aspect of the present application, there is also provided an alignment method for aligning an upper wafer and a lower wafer based on the wafer alignment device described above, comprising: corresponding to the upper wafer, setting a first detection position and a first wafer loading position; loading the upper wafer to an upper wafer loading plate at the first wafer loading position, and detecting alignment marks at the first detection position; corresponding to the lower wafer, setting a second detection position and a second wafer loading position; loading the lower wafer to a lower wafer loading plate at the second wafer loading position, and detecting alignment marks at the second detection position; when the upper wafer is at the first wafer loading position, the center line of the upper wafer along the Z-axis direction is a first Z-direction center line; when the upper wafer is at the first detection position, the center line of the upper wafer along the Z-axis direction is a second Z-direction center line; when the lower wafer is at the second wafer loading position, the center line of the lower wafer along the Z-axis direction is a third Z-direction center line; when the lower wafer is at the second detection position, the center line of the lower wafer along the Z-axis direction is a fourth Z-direction center line; the first Z-direction center line, the second Z-direction center line, the third Z-direction center line and the fourth Z-direction center line coincide; loading the upper wafer and the lower wafer to the upper wafer loading plate and the lower wafer loading plate respectively; and detecting alignment marks of the upper wafer and the lower wafer by the first visual detection system respectively.

[0026] The workbench is used as a basic structure of the whole device for bearing, and provides a stable mounting platform for each motion system and detection system, so that each component can keep accurate relative position during the bonding process. The wafer motion system is composed of an upper wafer motion system and a lower wafer motion system, and is used for controlling the motion of the upper wafer and the lower wafer respectively. The upper wafer carrier plate is used for bearing the upper wafer, and the motion of the upper wafer carrier plate is accurately controlled by the upper wafer motion system, so that the upper wafer can be accurately positioned at the bonding position. The lower wafer carrier plate is used for bearing the lower wafer, and the motion of the lower wafer carrier plate is accurately controlled by the lower wafer motion system, so that the lower wafer can be accurately transported from the upper piece position to the alignment position and the bonding position. Through the cooperation of the upper wafer motion system and the lower wafer motion system, the alignment and bonding of the upper wafer and the lower wafer can be successfully completed. The Y-axis motion component can provide the vision device with the freedom degree along the Y-axis direction, so that the vision device can move along the Y-axis direction to adjust the position. The Z-axis motion component can provide the vision device with the freedom degree in the vertical direction, so that the vision device can move along the Z-axis direction to adjust the position. The first cross beam is used for supporting the movable component and guiding the motion of the movable component along the Y-axis direction. The air foot component uses the air floating principle to make the movable component suspended relative to the first cross beam, so as to reduce the direct contact between the movable component and the first cross beam. Through the air foot component, the influence of the inclination or uneven surface of the first cross beam on the motion of the movable component can be avoided, so that the motion and positioning accuracy of the vision device are reduced. In addition, the wear problem caused by the direct contact between the first cross beam and the movable component can also be avoided. BRIEF DESCRIPTION OF DRAWINGS

[0027] The accompanying drawings, which form a part of the specification, are included to provide a further understanding of the application and are incorporated herein in conjunction with the description of the application. The embodiments of the present application, together with its advantages, can be understood by a study of the following detailed description, taken in conjunction with the drawings in which:

[0028] Figure 1 A first angle overall structure schematic view of a wafer alignment device of an embodiment of the present application is shown;

[0029] Figure 2 A second angle overall structure schematic view of a wafer alignment device of an embodiment of the present application is shown;

[0030] Figure 3 A front view of a wafer alignment device of an embodiment of the present application is shown;

[0031] Figure 4 A top view of a wafer alignment device of an embodiment of the present application is shown;

[0032] Figure 5 A left view of a wafer alignment device of an embodiment of the present application is shown;

[0033] Figure 6A right view of a wafer alignment device of an embodiment of the present application is shown;

[0034] Figure 7 A mounting schematic view of a first vision detection system of a wafer alignment device of an embodiment of the present application is shown;

[0035] Figure 8 A schematic view of an overall structure of a first vision detection system of a wafer alignment device of an embodiment of the present application is shown;

[0036] Figure 9 A schematic view of an overall structure of a second slide of a first vision detection system of a wafer alignment device of an embodiment of the present application is shown;

[0037] Figure 10 A schematic view of an overall structure of a top plate of a second slide of a first vision detection system of a wafer alignment device of an embodiment of the present application is shown;

[0038] Figure 11 A plan view of a first vision detection system of a wafer alignment device of an embodiment of the present application along an X direction is shown;

[0039] Figure 12 A cross-sectional view of a first vision detection system of a wafer alignment device of an embodiment of the present application is shown;

[0040] Figure 13 A plan view of a first vision detection system of a wafer alignment device of an embodiment of the present application along a Y direction is shown;

[0041] Figure 14 A mounting schematic view of a second vision detection system of a wafer alignment device of an embodiment of the present application is shown;

[0042] Figure 15 A schematic view of an overall structure of a second vision detection system of a wafer alignment device of an embodiment of the present application is shown;

[0043] Figure 16 A mounting position schematic view of a vision detection system of a wafer alignment device of an embodiment of the present application is shown;

[0044] Figure 17 A schematic view of a step of aligning an upper wafer and a lower wafer of a wafer alignment method of an embodiment of the present application is shown;

[0045] Figure 18 A schematic view of a step of aligning an upper wafer and a lower wafer of a wafer alignment method of another embodiment of the present application is shown.

[0046] Wherein, the above drawings include the following reference signs:

[0047] 1. Worktable; 11. Mounting hole; 12. Second crossbeam; 2. Upper wafer motion system; 21. Upper wafer carrier; 22. Inspection hole; 3. Lower wafer motion system; 31. Lower wafer carrier; 4. First mounting bracket; 41. First crossbeam; 5. First vision inspection system; 50. X-axis guide rail; 52. Vision device; 531. X-axis mover; 532. First mover plate; 54. First stator; 55. First guide rail; 57. First drive unit; 571. Second stator; 572. Second mover; 58. Movable assembly; 581. Base plate; 5821. First side plate; 5822. Second side plate; 583. Top plate; 586. First vacuum unit; 587. First air cushion; 588. Counterweight; 59. Z-axis motion assembly; 6. Second vision inspection system. Detailed Implementation

[0048] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0049] See also Figures 1 to 18 As shown, the present invention provides a wafer alignment device, which includes a worktable 1, an upper wafer motion system 2, a lower wafer motion system 3, and a first vision inspection system 5. The upper wafer motion system 2 includes an upper wafer carrier 21 for supporting the upper wafer; the lower wafer motion system 3 includes a lower wafer carrier 31 for supporting the lower wafer; the first vision inspection system 5 is disposed above the upper wafer motion system 2 and includes a Y-axis motion component, a Z-axis motion component 59, a vision device 52, a first mounting bracket 4, and an air foot component. The Y-axis motion component can drive the vision device 52 to move along the Y-axis direction, and the Z-axis motion component 59 can drive the vision device 52 to move along the Z-axis direction; the first mounting bracket 4 is disposed on the worktable 1 and includes a first crossbeam 41 extending along the X-axis direction; the Y-axis motion component includes a movable component 58, which is sleeved on the first crossbeam 41 and can move along the first crossbeam 41. The movable component 58 is air-bearingly engaged with the first crossbeam 41 through the air foot component.

[0050] In the above technical solution, the workbench 1 serves as a basic structure for bearing the whole device, and provides a stable mounting platform for each motion system and detection system, so as to ensure that each component can maintain an accurate relative position during the bonding process. The upper wafer motion system 2 and the lower wafer motion system 3 are respectively used for controlling the motion of the upper wafer and the lower wafer. The upper wafer carrier plate 21 is used for bearing the upper wafer, and the motion of the upper wafer carrier plate 21 is accurately controlled by the upper wafer motion system 2, so that the upper wafer can be accurately positioned at a bonding position. The lower wafer carrier plate 31 is used for bearing the lower wafer, and the motion of the lower wafer carrier plate 31 is accurately controlled by the lower wafer motion system 3, so that the lower wafer can be accurately transported from an upper piece position to an alignment position and a bonding position. Through the cooperation of the upper wafer motion system 2 and the lower wafer motion system 3, the alignment and bonding of the upper wafer and the lower wafer can be successfully completed. The Y-axis motion assembly can provide the vision device 52 with a degree of freedom in the Y-axis direction, so that the vision device 52 can move in the Y-axis direction to adjust the position. The Z-axis motion assembly can provide the vision device 52 with a degree of freedom in the vertical direction, so that the vision device 52 can move in the Z-axis direction to adjust the position. The first cross beam 41 is used for supporting the movable assembly 58 and guiding the motion of the movable assembly 58 in the Y-axis direction. The air foot assembly utilizes the air floating principle to enable the movable assembly 58 to be suspended relative to the first cross beam 41, thereby reducing the direct contact between the movable assembly 58 and the first cross beam 41. By arranging the air foot assembly, the influence of the inclination or uneven surface of the first cross beam 41 on the motion of the movable assembly 58 can be avoided, so as to reduce the motion and positioning accuracy of the vision device 52. In addition, the wear problem caused by the direct contact between the first cross beam 41 and the movable assembly 58 can also be avoided.

[0051] In an embodiment of the present application, the movable assembly 58 includes a top plate 583 located above the first cross beam 41, and the air foot assembly includes a first vacuum part 586 arranged on the top plate 583 or the first cross beam 41. The first vacuum part 586 can generate negative pressure to adsorb and fix the top plate 583 on the first cross beam 41.

[0052] In the above technical solution, the top plate 583, as a part of the movable assembly 58, is located above the first cross beam 41 and can contact the first cross beam 41. The first vacuum part 586 is arranged on the top plate 583 or the first cross beam 41, and is used for generating negative pressure between the top plate 583 and the first cross beam 41, so as to adsorb and fix the top plate 583 on the first cross beam 41. By arranging the first vacuum part 586 to adsorb and fix the top plate 583 on the first cross beam 41, vibration and deviation of the vision detection system during the Z-axis direction position adjustment and the vision detection process can be avoided, so as to ensure the accuracy and reliability of wafer alignment.

[0053] In one embodiment of the present application, the movable assembly 58 comprises a bottom plate 581 located below the first beam 41, and the air foot assembly comprises a first air cushion 587 and a first pre-tightening member in driving connection, the first air cushion 587 is arranged on one of the bottom plate 581 and the first beam 41, and the first pre-tightening member is capable of driving the first air cushion 587 to move up and down to provide a force to the other one of the bottom plate 581 and the first beam 41.

[0054] In the above technical solution, the bottom plate 581 is part of the movable assembly 58 and is located below the first beam 41. The first air cushion 587 can be arranged on one of the bottom plate 581 and the first beam 41, and the first pre-tightening member generally comprises a hydraulic cylinder or a pneumatic cylinder or an electric push rod and the like. When the first air cushion 587 is arranged on the bottom plate 581, the first pre-tightening member drives the first air cushion 587 to rise, so that the first air cushion 587 tightly presses the first beam 41, thereby ensuring that the movable assembly 58 is fixed relative to the first beam 41, at this time, the movable assembly 58 is in a locked state, and by driving the first air cushion 587 to lower through the first pre-tightening member, the first air cushion 587 is separated from the first beam 41, so that the switching of the movable assembly from the locked state to the unlocked state is completed. When the first air cushion 587 is arranged on the side of the first beam 41 facing the bottom plate 581, the first pre-tightening member can drive the first air cushion 587 to extend or retract towards the bottom plate 581, thereby realizing the switching of the movable assembly 58 between the locked state and the unlocked state, and the specific process is the same as when the first air cushion 587 is arranged on the bottom plate 581, which will not be described here.

[0055] In one embodiment of the present application, when the movable assembly 58 is in a movable state, the first air cushion 587 can be inflated by a gas source device such as an air pump, and the gas is blown out through the air holes on the surface of the air cushion, so as to form an activity gap between the movable assembly 58 and the first beam 41, thereby facilitating the movement of the movable assembly 58 along the first beam 41 without rigid contact and friction with the first beam 41, and reducing the friction.

[0056] In one embodiment of the present application, the first air cushion 587 is provided on one of the top plate 583 and the first cross beam 41, and the first pre-tightening member is capable of driving the first air cushion 587 to directly contact the other of the top plate 583 and the first cross beam 41, providing a force for the first air cushion 587 to tightly contact the other of the top plate 583 and the first cross beam 41, and achieving the tight fixing. When the first pre-tightening member drives the first air cushion 587 to a limited range, even if the first air cushion 587 is driven to the limit position, there is still a gap between the first air cushion 587 and the other of the top plate 583 and the first cross beam 41. At this time, the first air cushion 587 can be inflated by a gas source device such as a gas pump to expand the first air cushion 587 to fill the gap, thereby providing a force for the first air cushion 587 to tightly contact the other of the top plate 583 and the first cross beam 41, and achieving the tight fixing.

[0057] In one embodiment of the present application, the first pre-tightening member can be arranged on the top plate 583 or the first cross beam 41.

[0058] In the above technical solution, the first air cushion 587 is arranged on one of the top plate 583 and the first cross beam 41, and the first pre-tightening member is usually a hydraulic cylinder, a pneumatic cylinder or an electric push rod. The first pre-tightening member is mainly used to drive the first air cushion 587 to rise and fall, so that the first air cushion 587 can tightly contact the other of the top plate 583 and the first cross beam 41. Arranging the first pre-tightening member on the top plate 583 can increase the distance between the first pre-tightening member and the first air cushion 587, avoid interfering with the rising and falling or air floating action of the first air cushion 587, and reduce the complexity of the structure near the first air cushion 587, thereby improving the reliability of the air foot assembly. When the first pre-tightening member is a driving component such as an electric push rod, whose force attenuation is greatly affected by the distance, arranging the first pre-tightening member on the first cross beam 41 can shorten the distance of force conduction between the first pre-tightening member and the first air cushion 587, thereby improving the driving efficiency of the first pre-tightening member on the first air cushion 587.

[0059] In one embodiment of the present application, the air foot assembly comprises a second air cushion and a second pre-tightening member connected in driving mode. The second air cushion is arranged on one of the top plate 583 and the first cross beam 41, and the second pre-tightening member is capable of driving the second air cushion to rise and fall, thereby providing a force for the second air cushion to tightly contact the other of the top plate 583 and the first cross beam 41.

[0060] In the technical solution, the second air cushion is arranged on one of the top plate 583 and the first cross beam 41, and the second pre-tightening member can drive the second air cushion and provide a force for the second air cushion to tightly press the other one of the top plate 583 and the first cross beam 41. The specific process is the same as the cooperation between the first air cushion 587 and the first pre-tightening member, and will not be described here.

[0061] In one embodiment of the present application, the pressing surface of the first air cushion 587 and / or the second air cushion is a plane.

[0062] In the technical solution, the surface of the first air cushion 587 and / or the second air cushion in contact with and tightly pressing other surfaces is a pressing surface. By arranging the pressing surface as a plane, a stable and uniform contact interface can be provided for the air cushion, thereby improving the reliability and stability of the pressing of the air cushion and other surfaces.

[0063] In one embodiment of the present application, the movable assembly 58 includes a top plate 583 above the first cross beam 41 and a bottom plate 581 below the first cross beam 41. The air foot assembly further includes a first positive pressure part and a second positive pressure part. The first positive pressure part is arranged on the top plate 583 or the first cross beam 41, and the second positive pressure part is arranged on the bottom plate 581 or the first cross beam 41. The first positive pressure part and the second positive pressure part cooperate to enable the movable assembly 58 to be air-suspended on the first cross beam 41.

[0064] In the technical solution, the first positive pressure part is arranged on the top plate 583 or the first cross beam 41 to blow air into the gap between the top plate 583 and the first cross beam 41 to form a positive pressure. The second positive pressure part is arranged on the bottom plate 581 or the first cross beam 41 to blow air into the gap between the bottom plate 581 and the first cross beam 41 to form a positive pressure. The first positive pressure part and the second positive pressure part cooperate to form a positive pressure space between the top of the first cross beam 41 and the movable assembly 58 and between the bottom of the first cross beam 41 and the movable assembly 58, so that the movable assembly 58 is suspended on the first cross beam 41. This ensures that the movable assembly 58 and the vision detection system thereon do not come into contact with the first cross beam 41 during movement, avoids the influence of the inclination or uneven surface of the first cross beam 41 on the movement of the movable assembly 58, and reduces the movement and positioning accuracy of the vision detection system. At the same time, mechanical contact between the movable assembly 58 and the first cross beam 41 is avoided, and the influence of vibration and friction is avoided, thereby improving the movement accuracy and stability of the vision detection system.

[0065] In one embodiment of the present application, the movable assembly 58 includes a first side plate 5821 and a second side plate 5822 on both sides of the first cross beam 41. The outer side of the first side plate 5821 is provided with a Z-axis movement assembly 59, and the outer side of the second side plate 5822 is provided with a counterweight 588.

[0066] In the technical scheme, the first side plate 5821 and the second side plate 5822, together with the top plate 583 and the bottom plate 581, form the movable assembly 58, the first side plate 5821 is used for providing a mounting base for the Z-axis movement assembly 59, and the second side plate 5822 is used for providing a mounting base for the counterweight 588. The Z-axis movement assembly 59 is responsible for driving the visual detection system to move up and down along the Z-axis direction, so as to adapt to different wafer thicknesses and detection requirements of alignment marks. The counterweight 588 is installed outside the second side plate 5822, and the main purpose is to balance the weight of the Z-axis movement assembly 59, avoid tilting or shaking of the movable assembly 58 due to unbalanced gravity when the movable assembly 58 moves, and ensure the stability and precision of the visual detection system.

[0067] In one embodiment of the present application, the Y-axis movement assembly includes a first guide rail part 55 and a first driving part 57. The first guide rail part 55 is arranged on the first mounting frame 4 and extends along the Y-axis direction. The movable assembly 58 is in sliding cooperation with the first guide rail part 55. The first driving part 57 can drive the movable assembly 58 to slide along the first guide rail part 55. The Z-axis movement assembly 59 is installed on the movable assembly 58.

[0068] In the technical scheme, the first guide rail part 55 is arranged on the first mounting frame 4 and extends along the Y-axis direction, which can guide the movement of the movable assembly 58 along the Y-axis direction and avoid deviation of the movable assembly 58 during movement along the Y-axis direction. The first driving part 57 is used for driving the movable assembly 58 to slide along the first guide rail part 55, so as to realize smooth movement and accurate positioning of the movable assembly 58 along the Y-axis direction. By arranging the first guide rail part 55 and the first driving part 57, the visual detection system can be adjusted along the Y-axis direction under the driving of the movable assembly 58, and the accuracy of movement of the visual detection system along the Y-axis direction is improved.

[0069] In one embodiment of the present application, along the X-axis direction, the first guide rail part 55 includes a first inner side surface facing the side surface of the top plate 583 of the movable assembly 58. The air foot assembly further includes a third air cushion pad and a third pre-tightening part in driving connection. The third air cushion pad is arranged on one of the first inner side surface and the movable assembly 58. The third pre-tightening part can drive the third air cushion pad to move, so as to provide a force for the third air cushion pad to tightly press the other one of the first inner side surface and the movable assembly 58.

[0070] In the technical scheme, the first guide rail part 55 is provided with a guide groove extending along the Y-axis direction, the top plate 583 of the movable assembly 58 extends into the guide groove and can slide along the guide groove, the first inner side surface of the top plate 583 side of the first guide rail part 55 and one of the movable assembly 58 are provided with a third air cushion, when the third air cushion is arranged on the first inner side surface, the third pre-tightening part is usually a hydraulic cylinder, a pneumatic cylinder or an electric push rod, etc., the third pre-tightening part drives the third air cushion to move towards the movable assembly 58, so that the third air cushion abuts against the side surface of the top plate 583, thereby ensuring that the movable assembly 58 is fixed relative to the first guide rail part 55, at this time, the movable assembly 58 is in a locked state, by driving the third air cushion to lower through the third pre-tightening part, the third air cushion is separated from the movable assembly 58, so that the switching of the movable assembly 58 from the locked state to the unlocked state is completed, and it is ensured that the movable assembly 58 can move along the Y-axis direction under the guidance of the first guide rail part 55. When the third air cushion is arranged on the movable assembly 58, the third pre-tightening part drives the third air cushion to move towards the first inner side surface, so that the third air cushion abuts against the first inner side surface, thereby ensuring that the movable assembly 58 is fixed relative to the first guide rail part 55, at this time, the movable assembly 58 is in a locked state.

[0071] By arranging the third air cushion on one of the first inner side surface and the movable assembly 58, the movable assembly can be firmly fixed on the first guide rail part 55, and it is ensured that when the visual detection system moves along the X-axis direction with the first guide rail part 55 to adjust the position in the X-axis direction, the movable assembly 58 will not deviate due to vibration or sliding between the movable assembly 58 and the first guide rail part 55, thereby improving the positioning accuracy and detection accuracy of the visual detection system.

[0072] In one embodiment of the present application, along the X-axis direction, the first guide rail part 55 includes a second inner side surface opposite to the first inner side surface, the air foot assembly further includes a third positive pressure part arranged on the second inner side surface or the movable assembly 58, and the third positive pressure part and the third air cushion cooperate to provide guidance for the movement of the movable assembly 58 in the Y-axis direction.

[0073] In the technical scheme, when the movable assembly 58 is in a movable state, the third air cushion can be inflated by a gas source device such as a gas pump, and the gas is blown out through the gas holes on the surface of the third air cushion, so that an activity gap is formed between the movable assembly 58 and the first inner side surface, and the movable assembly 58 is suspended relative to the first inner side surface, thereby avoiding rigid contact and friction between the movable assembly 58 and the first guide rail part 55 when the movable assembly 58 moves along the first guide rail part 55. The third positive pressure part is arranged on the second inner side surface or the movable assembly 58, and is used to form an activity gap between the second inner side surface and the movable assembly 58, so that the movable assembly 58 is suspended relative to the second inner side surface.

[0074] By setting the third positive pressure part and using the third positive pressure part and the third air cushion pad in cooperation, positive pressure is formed by blowing air from both sides of the movable assembly 58, the movable assembly 58 is suspended relative to the first guide rail part 55, and the movement of the movable assembly 58 in the Y-axis direction is guided. When the first guide rail part 55 guides the movement of the movable assembly 58 in the Y-axis direction, contact between the movable assembly 58 and the inner side surface of the first guide rail part 55 can be avoided, thereby avoiding vibration of the first guide rail part 55 caused by friction during movement of the movable assembly 58 in the Y-axis direction, significantly improving the stability and accuracy of movement of the movable assembly 58 in the Y-axis direction, and further improving the positioning accuracy of the visual inspection system connected to the movable assembly 58.

[0075] In one embodiment of the present application, along the X-axis direction, the first guide rail part 55 further includes a second inner side surface opposite the first inner side surface, and the air foot assembly further includes a third vacuum part, which is arranged on the second inner side surface or the movable assembly 58. The third vacuum part can generate negative pressure to adsorb and fix the movable assembly 58 on the first guide rail part 55.

[0076] In the above technical solution, the third vacuum part is arranged on the second inner side surface or the movable assembly 58, and the third vacuum part is used to generate negative pressure to adsorb and fix the movable assembly 58 on the first guide rail part 55, thereby achieving fixation of the movable assembly 58. The third vacuum part can be used alone or in cooperation with the third air cushion pad. The third pre-tightening member drives the third air cushion pad to tightly fix the movable assembly 58 from one side of the movable assembly 58 toward the first inner side surface, while the third vacuum part can adsorb and fix the movable assembly 58 from one side of the movable assembly 58 toward the second inner side surface. Through cooperation of the third vacuum part and the third air cushion pad, the fixation effect of the movable assembly 58 is further improved, the possibility of deviation of the movable assembly 58 relative to the first guide rail part 55 under external force is significantly reduced, and the positioning accuracy and reliability of the visual inspection system connected to the movable assembly 58 are further improved.

[0077] In one embodiment of the present application, a groove extending in the Y direction is arranged on the top plate 583 of the movable assembly 58. Along the X-axis direction, the groove includes a third inner side surface and a fourth inner side surface. Along the X-axis direction, the first guide rail part includes a first outer side surface facing the third inner side surface. The air foot assembly further includes a fourth air cushion pad and a fourth pre-tightening member in driving connection. The fourth air cushion pad is arranged on one of the third inner side surface and the first outer side surface. The fourth pre-tightening member can drive the fourth air cushion pad to move to provide a force to tightly press the other one of the third inner side surface and the first outer side surface.

[0078] In the technical scheme, the top plate 583 of the movable assembly 58 is provided with a groove extending along the Y direction, the first guide rail part can extend into the groove and cooperate with the groove to guide the movement of the movable assembly 58 along the Y axis. Along the X axis, the groove comprises a third inner side and a fourth inner side, the fourth air cushion is arranged on one of the third inner side and the first outer side, and the cooperation process of the fourth air cushion and the fourth pre-tightening part is the same as that of the third pre-tightening part and the third air cushion, which will not be repeated here. By arranging the fourth air cushion and the fourth pre-tightening part, the movable assembly 58 can be relatively fixed on the first guide rail part 55, so that the movable assembly 58 is prevented from being deviated relative to the first guide rail part 55 under the action of external force, thereby improving the positioning accuracy and reliability of the vision detection system connected with the movable assembly 58.

[0079] In one embodiment of the present application, along the X axis, the first guide rail part further comprises a second outer side opposite to the first outer side, the second outer side faces the fourth inner side; and the air foot assembly further comprises a fourth positive pressure part arranged on the second outer side or the fourth inner side, the fourth positive pressure part can cooperate with the fourth air cushion to guide the movement of the movable assembly 58 along the Y axis.

[0080] In the technical scheme, the fourth positive pressure part has the same working process as the third positive pressure part, which will not be repeated here. By arranging the fourth positive pressure part and cooperating the fourth positive pressure part with the fourth air cushion, the movable assembly 58 is suspended relative to the first guide rail part 55, and the movement of the movable assembly 58 along the Y axis is guided. When the first guide rail part 55 guides the movement of the movable assembly 58 along the Y axis, the movable assembly 58 is also prevented from contacting the outer side of the first guide rail part 55, so that the movable assembly 58 is prevented from vibrating due to friction with the first guide rail part 55 during the movement along the Y axis, the stability and accuracy of the movement of the movable assembly 58 along the Y axis are significantly improved, and the positioning accuracy of the vision detection system connected with the movable assembly 58 is improved.

[0081] In one embodiment of the present application, along the X axis, the first guide rail part further comprises a second outer side opposite to the first outer side, the second outer side faces the fourth inner side; and the air foot assembly further comprises a second vacuum part arranged on the second outer side or the fourth inner side, the second vacuum part can generate negative pressure to adsorb and fix the movable assembly on the first guide rail part.

[0082] In the technical scheme, the second vacuum part is arranged on the second outer side or the fourth inner side to generate negative pressure to adsorb the movable assembly 58 on the first guide rail part 55, so as to fix the movable assembly 58. The second vacuum part can be used alone or in cooperation with the fourth air cushion. The fourth pre-tightening part drives the fourth air cushion to tightly fix the movable assembly 58 from the groove to the side of the first outer side. At the same time, the second vacuum part can adsorb and fix the movable assembly 58 from the groove to the side of the second outer side. Through cooperation of the second vacuum part and the fourth air cushion, the fixing effect of the movable assembly 58 is further improved, the possibility of deviation of the movable assembly 58 relative to the first guide rail part 55 under external force is significantly reduced, and the positioning accuracy and reliability of the visual inspection system connected with the movable assembly 58 are further improved.

[0083] In an embodiment of the present application, the first visual inspection system 5 further comprises an X-axis motion assembly, the X-axis motion assembly comprising an X-axis guide rail part 50 and a second driving part. The X-axis guide rail part 50 is arranged on the first mounting frame 4 and extends along the X-axis direction. The second driving part comprises a first stator part 54 and a first mover part. The first stator part 54 is arranged on the first mounting frame 4 and is drivingly connected with the first mover part. The first mover part is in sliding cooperation with the X-axis guide rail part 50. The movable assembly 58 is arranged on the first mover part. The first mover part can drive the movable assembly 58 to move along the first cross beam 41 in the X-axis direction.

[0084] In the technical scheme, the X-axis guide rail part 50 is used to guide the sliding of the first mover part, so as to ensure that the first mover part can smoothly and accurately move along the X-axis direction. The second driving part comprises the first stator part 54 and the first mover part. The first stator part 54 is arranged on the first mounting frame 4. The first mover part is connected with the movable assembly 58. Under electromagnetic driving cooperation of the first stator part 54 and the first mover part, the first stator part 54 can drive the first mover part to slide along the X-axis guide rail part 50, and in turn drive the movable assembly 58 to move in the X-axis direction. By arranging the X-axis motion assembly, the visual inspection system is provided with a degree of freedom in the X-axis direction. In cooperation with the Y-axis motion assembly, the wafer alignment device realizes double-axis motion control of the visual inspection system in the X-axis and Y-axis directions, and enhances the alignment detection capability and flexibility of the system.

[0085] In an embodiment of the present application, the first guide rail part is connected with the first mover part and arranged on the movable assembly 58.

[0086] In the technical solution, the first guide rail part 55 is connected with the first mover part, when the first mover plate of the first mover part slides along the X-axis guide rail part under the electromagnetic driving force of the first stator part, the first guide rail part 55 can slide along the X-axis direction, and in the embodiment, the first guide rail part 55 is a guide rail structure with a guide groove arranged at the bottom, the first guide rail part 55 is sleeved on the top plate 583 of the movable assembly 58, and the top plate 583 extends into the guide groove, so that the movable assembly 58 moves along with the first guide rail part 55 and the first mover part, and then the visual detection system on the movable assembly 58 is provided with the freedom of movement along the X-axis direction.

[0087] In an embodiment of the present application, the Y-axis movement assembly includes a first driving part 57, the first driving part 57 includes a second stator part 571 and a second mover part 572, the second stator part 571 is arranged on the first guide rail part, and the second mover part 572 is arranged on the top plate 583 above the first cross beam 41, and the second stator part 571 and the second mover part 572 are drivingly matched.

[0088] In the technical solution, the first driving part 57 is used to provide driving force for the movable assembly 58 to move along the Y-axis direction, the first driving part 57 includes the second stator part 571 and the second mover part 572, the second stator part 571 is arranged on the first guide rail part, and the second mover part 572 is arranged on the top plate 583 above the first cross beam 41, and through the electromagnetic driving cooperation between the second stator part 571 and the second mover part 572, the movable assembly 58 can be driven to move along the first guide rail part in the Y-axis direction.

[0089] In an embodiment of the present application, when the movable assembly 58 is in the active state, the first air cushion pad 587 can be inflated by a gas source device such as a gas pump, only the air gap between the bottom plate 581 and the first cross beam 41 is formed by the first air cushion pad 587, so that the movable assembly 58 is suspended relative to the first cross beam 41, and then the movable assembly 58 is driven to move along the first cross beam 41, so that the movable assembly 58 and the first cross beam 41 are avoided from directly contacting, and the movement of the movable assembly 58 is ensured not to be affected by the machining error or surface quality of the first cross beam 41, so that the precision of the movement and positioning of the movable assembly 58 is improved.

[0090] In addition, the first air cushion 587 can form an air gap between the bottom plate 581 and the first beam 41, and the second air cushion can be inflated by the air source device such as an air pump, and the gas is blown out through the air holes on the surface of the second air cushion, thereby forming an air gap between the top plate 583 and the first beam 41, and the air gap is formed between the top and bottom of the first beam 41 and the movable assembly 58, and the movable assembly 58 is completely suspended on the first beam 41, thereby further reducing the probability of contact between the movable assembly 58 and any one of the top surface or the bottom surface of the first beam 41, and significantly improving the accuracy of movement and positioning of the movable assembly 58.

[0091] Alternatively, only the second positive pressure part is started, and the air gap is formed between the bottom plate 581 and the first beam 41 by the second positive pressure part, so that the movable assembly 58 is suspended relative to the first beam 41, and direct contact between the movable assembly 58 and the first beam 41 during movement is avoided, and the movement of the movable assembly 58 is not affected by the machining error or surface quality of the first beam 41, thereby improving the accuracy of movement and positioning of the movable assembly 58.

[0092] In addition, on the basis of starting the second positive pressure part, the first positive pressure part can also be started, or the air source device such as the air pump can be started to inflate the second air cushion and blow out the gas through the air holes on the surface of the second air cushion, thereby forming an air gap between the top plate 583 and the first beam 41, and the air gap is formed between the top and bottom of the first beam 41 and the movable assembly 58, and the movable assembly 58 is completely suspended on the first beam 41, thereby further reducing the probability of contact between the movable assembly 58 and any one of the top surface or the bottom surface of the first beam 41, and significantly improving the accuracy of movement and positioning of the movable assembly 58.

[0093] In an embodiment of the present application, when the movable assembly 58 is in the locked state, the first pre-tightening member can be started alone to drive the first air cushion 587 to move and abut against the first beam 41, thereby ensuring that the movable assembly 58 is fixed relative to the first beam 41. The second pre-tightening member can also be started alone to drive the second air cushion to move and abut against the first beam 41, thereby ensuring that the movable assembly 58 is fixed relative to the first beam 41.

[0094] Alternatively, the first vacuum part 586 can be started alone to generate negative pressure between the top plate 583 and the first beam 41, thereby adsorbing and fixing the top plate 583 on the first beam 41.

[0095] In addition, the first vacuum part 586 can be started at the same time as starting the first pre-tightening part, at this time, the first pre-tightening part drives the first air cushion 587 to move and tightly press the first cross beam 41 from the bottom of the first cross beam 41, and at the same time, the first vacuum part 586 generates negative pressure between the top plate 583 and the first cross beam 41, and the top plate 583 is adsorbed and fixed on the first cross beam 41, and through the cooperation of the first vacuum part 586 and the first air cushion 587, the top plate 583 is tightly fixed from below and adsorbed and fixed from above, which further improves the fixing effect of the movable assembly 58, significantly reduces the possibility of the movable assembly 58 being deviated relative to the first guide rail part 55 under the action of external force, and further improves the positioning accuracy and reliability of the visual inspection system connected with the movable assembly 58.

[0096] In one embodiment of the present application, the wafer alignment device further comprises a second visual inspection system 6, which is arranged in correspondence with the first visual inspection system 5 in the Z-axis direction and is located below the lower wafer movement system.

[0097] In the above technical solution, the specific structure and connection relationship of the second visual inspection system 6 are the same as those of the first visual inspection system 5, and thus will not be described again, and the difference lies in that the second visual inspection system 6 is located below the lower wafer movement system, and the visual device of the second visual inspection system 6 faces upward, so that the second visual inspection system 6 can detect the alignment mark of the lower wafer from the bottom of the lower wafer. The second visual inspection system 6 cooperates with the first visual inspection system 5, so that the wafer alignment device can detect the alignment mark of the lower wafer through the second visual inspection system 6 while detecting the alignment mark of the upper wafer through the first visual inspection system 5, which significantly improves the efficiency of the preparation work before wafer bonding, shortens the bonding period, and thus improves the production efficiency of wafer bonding.

[0098] In one embodiment of the present application, the workbench 1 is provided with a mounting hole 11, and the second visual inspection system 6 is arranged on the second cross beam 12 and can slide along the second cross beam 12.

[0099] In the above technical solution, the second visual inspection system 6 is arranged on the second cross beam 12 and can slide along the second cross beam 12, the second cross beam 12 is used for bearing the second visual inspection system 6 and guiding the movement of the second visual inspection system 6 in the X-axis direction, and the mounting hole 11 is used for ensuring that the second visual inspection system 6 can pass through the workbench 1 and be installed on the second cross beam 12.

[0100] In one embodiment of the present application, the upper wafer carrier plate 21 is provided with a detection hole 22, and the first visual inspection system 5 can detect the alignment mark of the lower wafer on the lower wafer carrier plate 31 through the detection hole 22.

[0101] In the technical scheme, only the first visual detection system 5 is arranged to detect the upper wafer and the lower wafer, the detection hole 22 provides a channel for the visual device of the first visual detection system 5 to detect the alignment mark of the lower wafer through the upper wafer carrier plate 21, and the first visual detection system 5 located above the upper wafer carrier plate 21 can avoid the obstruction of the upper wafer carrier plate 21 and smoothly detect the alignment mark of the lower wafer on the lower wafer carrier plate 31.

[0102] In one embodiment of the present application, the first positive pressure part can be arranged on one side of the top plate 583 facing the first cross beam 41, or the first positive pressure part can be arranged on one side of the first cross beam 41 facing the top plate 583.

[0103] In the technical scheme, the first positive pressure part can be arranged on one side of the top plate 583 facing the first cross beam 41, or the first positive pressure part can be arranged on one side of the first cross beam 41 facing the top plate 583. As long as the first positive pressure part can generate a positive pressure air gap between the top plate 583 and the first cross beam 41, a non-contact supporting force between the top plate 583 and the first cross beam 41 can be generated, so that direct contact between the movable assembly 58 and the first cross beam 41 during relative movement is avoided, friction and vibration are caused, the movement accuracy and stability of the visual detection system are improved, mechanical wear is reduced, and the service life of the equipment is prolonged.

[0104] In one embodiment of the present application, the second positive pressure part can be arranged on one side of the bottom plate 581 facing the first cross beam 41, or the second positive pressure part can be arranged on one side of the first cross beam 41 facing the bottom plate 581.

[0105] In the technical scheme, the second positive pressure part can be arranged on one side of the bottom plate 581 facing the first cross beam 41, or the second positive pressure part can be arranged on one side of the first cross beam 41 facing the bottom plate 581. As long as the second positive pressure part can generate a positive pressure air gap between the bottom plate 581 and the first cross beam 41, a non-contact supporting force between the bottom plate 581 and the first cross beam 41 can be generated, so that direct contact between the movable assembly 58 and the first cross beam 41 during relative movement is avoided, friction and vibration are caused, the movement accuracy and stability of the visual detection system are improved, mechanical wear is reduced, and the service life of the equipment is prolonged.

[0106] In one embodiment of the present application, the positive pressure part includes a gas hole arranged on the movable assembly 58 or the first cross beam 41, the gas hole is communicated with a gas supply device such as a gas pump through a gas conveying pipe, and the gas supply device is started during use. Gas is sprayed from the gas hole to the movable assembly 58 and the first cross beam 41 through the gas conveying pipe, so that a positive pressure is formed between the movable assembly 58 and the first cross beam 41, and the movable assembly 58 can be air-suspended relative to the first cross beam 41.

[0107] In one embodiment of the present application, the vacuum part comprises adsorption holes or adsorption grooves arranged on the movable assembly 58 or the first cross beam 41, and the adsorption holes or adsorption grooves are communicated with an air exhaust device such as a vacuum pump through a gas conveying pipe. In use, the air exhaust device is started to exhaust the air between the movable assembly 58 and the first cross beam 41 through the gas conveying pipe to form a negative pressure, thereby ensuring that the movable assembly 58 can be stably adsorbed on the first cross beam 41.

[0108] In one embodiment of the present application, when the first visual detection system 5 further comprises an X-axis movement assembly, the X-axis guide rail part 50 is arranged on the first mounting frame 4, and the first guide rail part 55 is connected with the first mover plate 532. The first guide rail part 55 and the first mover plate 532 are arranged on the X-axis guide rail part 50 together and can slide along the X-axis guide rail part 50.

[0109] In the above technical solution, the X-axis guide rail part 50 is arranged on the first mounting frame 4 to provide guidance and support for the first guide rail part 55 and the first mover plate 532 in the X-axis direction. The connection of the first guide rail part 55 and the first mover plate 532 enables the first guide rail part 55 and the first mover plate 532 to slide on the X-axis guide rail part 50 together.

[0110] In one embodiment of the present application, the first mover part comprises an X-axis mover 531 and a first mover plate 532. The X-axis mover 531 and the first mover plate 532 can be arranged separately and connected together, or can be arranged integrally.

[0111] In the above technical solution, the X-axis mover 531 and the first mover plate 532 are arranged separately, so that they can be designed and manufactured separately, reducing the difficulty of processing and manufacturing, while ensuring that the X-axis mover 531 and the first mover plate 532 can be independently maintained and replaced, reducing maintenance cost and time. The X-axis mover 531 and the first mover plate 532 are arranged integrally, which can provide better structural rigidity, reduce vibration during movement, and improve positioning accuracy. At the same time, the assembly process of the X-axis mover 531 and the first mover plate 532 on the production line is simplified, and the production efficiency is improved.

[0112] In one embodiment of the present application, the X-axis guide rail part comprises a guide rail in the form of air suspension or magnetic suspension, so that the first mover part can be suspended relative to the X-axis guide rail part and slide with the X-axis guide rail part.

[0113] In the above technical solution, the air suspension guide rail converts physical contact into non-contact air cushion support by generating a thin air cushion between the guide rail and the mover part, thereby greatly reducing the friction. The magnetic suspension guide rail uses electromagnetic force to suspend the first mover part above the X-axis guide rail part, and controls the suspension height and movement direction by adjusting the size of the electromagnetic force. This guide rail form also avoids direct physical contact and provides a high-precision, high-response motion platform. Whether air suspension or magnetic suspension guide rail is used, the purpose is to enable the first mover part to be suspended relative to the X-axis guide rail part, reduce physical contact and friction between the first mover part and the guide rail, thereby reducing vibration during movement and improving positioning accuracy.

[0114] In one embodiment of the application, the X-axis mover 531 is a magnetic steel.

[0115] In the above technical solution, the X-axis mover 531 is made of magnetic steel material, and cooperates with the first stator part 54 with a coil to generate electromagnetic force between the X-axis mover 531 and the first stator part 54. The X-axis mover 531 can move along the X-axis guide rail part 50 under the action of the electromagnetic force, thereby driving the visual inspection system to adjust the position in the X-axis direction.

[0116] In one embodiment of the application, the first mover plate 532 is a long strip plate extending along the X-axis direction, and a platform for accommodating the X-axis mover 531 is arranged thereon. The first mover plate 532 has an L-shaped cross-sectional shape along the YOZ plane.

[0117] In the above technical solution, the long strip structure of the first mover plate 532 extends along the X-axis direction, providing sufficient support area for the X-axis mover 531, which helps to reduce vibration during high-speed movement, thereby improving the stability of the first visual inspection system. The first mover plate 532 with an L-shaped cross-sectional shape reserves an accommodation position for the X-axis mover 531. After the X-axis mover 531 is installed on the first mover plate 532, the whole formed by the two does not interfere with other components, improving the space utilization.

[0118] In one embodiment of the application, the first guide rail part 55 is connected to the first mover plate 532 on the side surface, and a guide groove extending along the Y-axis direction is formed in the bottom of the first guide rail part 55, so that the first guide rail part 55 has a C-shaped structure with the opening downward.

[0119] In the technical scheme, the bottom of the first guide rail part 55 is provided with a guide groove to form a C-shaped structure with the opening downward, the guide groove is mainly used for accommodating the movable assembly 58 and guiding the movement of the movable assembly 58 along the Y-axis direction, so as to ensure the smooth movement of the movable assembly 58 along the Y-axis direction and prevent the movable assembly 58 from deviating or shaking during the movement. The side surface of the guide groove provides a space for the air floating assembly, and a positive pressure part or an air floating pad can be arranged in the space, so that the air floating state is formed between the movable assembly 58 and the first guide rail part 55, the friction is reduced, the interference of the first guide rail part 55 on the Y-direction movement of the movable assembly 58 is reduced, and the accuracy and stability of the movement of the movable assembly 58 are improved.

[0120] In one embodiment of the present application, a first detection position and a first wafer loading position are arranged corresponding to the upper wafer, the upper wafer is loaded on the upper wafer carrier 21 at the first wafer loading position, and the alignment mark detection is performed on the upper wafer at the first detection position; a second detection position and a second wafer loading position are arranged corresponding to the lower wafer, the lower wafer is loaded on the lower wafer carrier 31 at the second wafer loading position, and the alignment mark detection is performed on the lower wafer at the second detection position; when the upper wafer is at the first wafer loading position, the center line of the upper wafer along the Z-axis direction is a first Z-direction center line; when the upper wafer is at the first detection position, the center line of the upper wafer along the Z-axis direction is a second Z-direction center line; when the lower wafer is at the second wafer loading position, the center line of the lower wafer along the Z-axis direction is a third Z-direction center line; when the lower wafer is at the second detection position, the center line of the lower wafer along the Z-axis direction is a fourth Z-direction center line; the first Z-direction center line, the second Z-direction center line, the third Z-direction center line and the fourth Z-direction center line coincide.

[0121] In the technical scheme, the wafer loading position is the first station of the wafer entering the wafer alignment device, the wafer carrier waits for the wafer to be loaded at the wafer loading position, and then the wafer is accurately transported from the storage or transportation position to the wafer loading position and placed on the wafer carrier, so as to realize accurate wafer loading. The first wafer loading position corresponds to the position where the upper wafer is placed on the upper wafer carrier 21, and the second wafer loading position corresponds to the position where the lower wafer is placed on the lower wafer carrier 31. The detection position is a position where the visual detection system can accurately detect the alignment mark on the wafer, the first detection position corresponds to the position where the visual detection system detects the upper wafer on the upper wafer carrier, and the second detection position corresponds to the position where the visual detection system detects the lower wafer on the lower wafer carrier.

[0122] The center line of the upper wafer along the Z-axis direction is a first Z-direction center line when the upper wafer is at the first wafer loading position; the center line of the upper wafer along the Z-axis direction is a second Z-direction center line when the upper wafer is at the first detection position; the center line of the lower wafer along the Z-axis direction is a third Z-direction center line when the lower wafer is at the second wafer loading position; the center line of the lower wafer along the Z-axis direction is a fourth Z-direction center line when the lower wafer is at the second detection position; the first Z-direction center line, the second Z-direction center line, the third Z-direction center line and the fourth Z-direction center line coincide, indicating that the wafer loading, detection and conveying between the wafer loading position and the detection position of the upper wafer and the lower wafer are all completed in the same vertical space, avoiding movement of the wafer in the horizontal plane along the X-axis or Y-axis direction, simplifying the adjustment steps in the alignment process, thereby reducing unnecessary movement and time waste, and improving production efficiency.

[0123] With reference to Figures 1 to 18 The alignment method provided by the application is based on the wafer alignment device of the above-mentioned embodiments, and comprises the following steps: corresponding to the upper wafer, a first detection position and a first wafer loading position are arranged; the upper wafer is loaded onto the upper wafer carrier 21 at the first wafer loading position, and the upper wafer is subjected to alignment mark detection at the first detection position; corresponding to the lower wafer, a second detection position and a second wafer loading position are arranged; the lower wafer is loaded onto the lower wafer carrier 31 at the second wafer loading position, and the lower wafer is subjected to alignment mark detection at the second detection position; the center line of the upper wafer along the Z-axis direction is a first Z-direction center line when the upper wafer is at the first wafer loading position; the center line of the upper wafer along the Z-axis direction is a second Z-direction center line when the upper wafer is at the first detection position; the center line of the lower wafer along the Z-axis direction is a third Z-direction center line when the lower wafer is at the second wafer loading position; the center line of the lower wafer along the Z-axis direction is a fourth Z-direction center line when the lower wafer is at the second detection position; the first Z-direction center line, the second Z-direction center line, the third Z-direction center line and the fourth Z-direction center line coincide; the upper wafer and the lower wafer are loaded onto the upper wafer carrier 21 and the lower wafer carrier 31 respectively; and the first visual detection system performs alignment mark detection on the upper wafer and the lower wafer respectively.

[0124] In the above technical solution, the wafer alignment device only includes the first visual detection system, and the alignment mark of the upper wafer and the lower wafer is detected by the first visual detection system respectively. When the wafer alignment device of the above embodiment is used to align the upper wafer and the lower wafer, the lower wafer carrier plate 31 is first moved to the second wafer loading position and the lower wafer is loaded onto the lower wafer carrier plate 31, then the lower wafer carrier plate 31 is moved to transport the lower wafer to the second detection position, and then the first visual detection system detects the alignment mark of the lower wafer through the detection hole 22 of the upper wafer carrier plate 21. After the detection of the lower wafer is completed, the upper wafer carrier plate 21 is moved to the first wafer loading position and the upper wafer is loaded onto the upper wafer carrier plate 21, then the upper wafer carrier plate 21 is moved to transport the lower wafer to the first detection position, and then the first visual detection system detects the alignment mark of the upper wafer. The loading, alignment and bonding of the wafer are all completed in the same vertical movement area, avoiding the movement of the wafer in the horizontal plane along the X-axis or Y-axis direction, greatly shortening the movement distance of the upper and lower wafers from the loading position to the alignment position, thereby reducing the transportation time of the wafers from the loading position to the alignment position, improving the continuity and speed of the entire alignment and bonding process, and further improving the production efficiency of the alignment and bonding.

[0125] For reference Figures 1 to 18 As shown in the drawings, the present application also provides an alignment method based on the wafer alignment device of the above embodiment for aligning the upper wafer and the lower wafer, which comprises: corresponding to the upper wafer, a first detection position and a first wafer loading position are arranged; the upper wafer is loaded onto the upper wafer carrier plate 21 at the first wafer loading position, and the alignment mark of the upper wafer is detected at the first detection position; corresponding to the lower wafer, a second detection position and a second wafer loading position are arranged; the lower wafer is loaded onto the lower wafer carrier plate 31 at the second wafer loading position, and the alignment mark of the lower wafer is detected at the second detection position; when the upper wafer is at the first wafer loading position, the center line of the upper wafer along the Z-axis direction is the first Z-direction center line; when the upper wafer is at the first detection position, the center line of the upper wafer along the Z-axis direction is the second Z-direction center line; when the lower wafer is at the second wafer loading position, the center line of the lower wafer along the Z-axis direction is the third Z-direction center line; when the lower wafer is at the second detection position, the center line of the lower wafer along the Z-axis direction is the fourth Z-direction center line; the first Z-direction center line, the second Z-direction center line, the third Z-direction center line and the fourth Z-direction center line coincide; the upper wafer and the lower wafer are loaded onto the upper wafer carrier plate 21 and the lower wafer carrier plate 31 respectively; the first visual detection system detects the alignment mark of the upper wafer; and the second visual detection system detects the alignment mark of the lower wafer.

[0126] In the above technical solution, the wafer alignment device comprises a first visual detection system and a second visual detection system, the first visual detection system detects the alignment mark of the upper wafer, and the second visual detection system detects the alignment mark of the lower wafer. When the upper wafer and the lower wafer are aligned, the upper wafer carrier 21 is moved to the first wafer loading position and the upper wafer is loaded onto the upper wafer carrier 21, then the upper wafer carrier 21 is moved to deliver the lower wafer to the first detection position, the first visual detection system detects the alignment mark of the upper wafer, at the same time, the lower wafer carrier 31 is moved to the second wafer loading position and the lower wafer is loaded onto the lower wafer carrier 31, then the lower wafer carrier 31 is moved to deliver the lower wafer to the second detection position, and the second visual detection system detects the alignment mark of the lower wafer. The wafer loading, alignment and bonding of the wafer are all completed in the same vertical movement area, avoiding the movement of the wafer in the horizontal plane along the X-axis or Y-axis direction, greatly shortening the movement distance of the upper and lower wafers from the wafer loading position to the alignment position, thereby reducing the wafer delivery time from the wafer loading position to the alignment position. In addition, since two sets of visual detection systems are provided to detect the alignment marks of the upper wafer and the lower wafer respectively, the wafer alignment device can simultaneously perform wafer loading, delivery and alignment detection of the upper wafer and the lower wafer, greatly improving the continuity and speed of the entire alignment and bonding process, and significantly improving the production efficiency of the alignment and bonding.

[0127] Obviously, the above-described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor should belong to the scope of protection of the present application.

[0128] It should be noted that the terms used herein are only intended to describe specific embodiments, and are not intended to limit the exemplary embodiments according to the present application. As used herein, the singular form is intended to include the plural form unless the context clearly indicates otherwise, and it should be understood that when the terms "comprise" and / or "include" are used in the specification, there is a feature, step, work, device, component and / or combination thereof.

[0129] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Those skilled in the art can make various changes and modifications to the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the scope of protection of the present application.

Claims

1. A wafer alignment device, comprising: a worktable (1); an upper wafer movement system (2) comprising an upper wafer carrier plate (21) for carrying an upper wafer; a lower wafer movement system (3) comprising a lower wafer carrier plate (31) for carrying a lower wafer; characterized in that it further comprises: a first vision detection system (5) arranged above the upper wafer movement system (2); the first vision detection system (5) comprising: a Y-axis movement assembly, a Z-axis movement assembly (59), and a vision device (52), the Y-axis movement assembly being capable of moving the vision device (52) along a Y-axis direction, and the Z-axis movement assembly (59) being capable of moving the vision device (52) along a Z-axis direction; a first mounting frame (4) arranged on the worktable (1), the first mounting frame (4) comprising a first cross beam (41) extending along an X-axis direction; the Y-axis movement assembly comprising: a movable assembly (58) sleeved on the first cross beam (41) and capable of moving along the first cross beam (41); 2. The wafer alignment device of claim 1, wherein an air foot assembly, the movable assembly (58) being in air floating cooperation with the first cross beam (41) through the air foot assembly. the movable assembly (58) comprising a top plate (583) located above the first cross beam (41); the air foot assembly comprising a first vacuum portion (586) arranged on the top plate (583) or the first cross beam (41), the first vacuum portion (586) being capable of generating negative pressure to adsorb and fix the top plate (583) on the first cross beam (41); and / or, the movable assembly (58) comprising a bottom plate (581) located below the first cross beam (41), the air foot assembly comprising a first air floating pad (587) and a first pre-tightening member in driving connection, the first air floating pad (587) being arranged on one of the bottom plate (581) and the first cross beam (41), and the first pre-tightening member being capable of driving the first air floating pad (587) to move up / down to provide a force to the other one of the bottom plate (581) and the first cross beam (41) to press against it; 3. The wafer alignment device of claim 1, wherein and / or, the air foot assembly comprising a second air floating pad and a second pre-tightening member in driving connection, the second air floating pad being arranged on one of the top plate (583) and the first cross beam (41), and the second pre-tightening member being capable of driving the second air floating pad to move up / down to provide a force to the other one of the top plate (583) and the first cross beam (41) to press against it. the movable assembly (58) comprising a top plate (583) located above the first cross beam (41) and a bottom plate (581) located below the first cross beam (41), and the air foot assembly further comprising a first positive pressure portion and a second positive pressure portion. The first positive pressure part is arranged on the top plate (583) or the first cross beam (41), the second positive pressure part is arranged on the bottom plate (581) or the first cross beam (41), and the first positive pressure part and the second positive pressure part cooperate to enable the movable assembly (58) to be air-suspended on the first cross beam (41).

4. The wafer alignment device of claim 1, wherein, The movable assembly (58) comprises a first side plate (5821) and a second side plate (5822) located on both sides of the first cross beam (41), the outer side of the first side plate (5821) is provided with the Z-axis movement assembly (59), and the outer side of the second side plate (5822) is provided with a counterweight (588).

5. The wafer alignment device of claim 1, wherein The Y-axis movement assembly comprises a first guide rail part (55) and a first driving part (57), the first guide rail part (55) is arranged on the first mounting frame (4) and extends in the Y-axis direction, the movable assembly (58) is in sliding cooperation with the first guide rail part (55), and the first driving part (57) can drive the movable assembly (58) to slide along the first guide rail part (55), and the Z-axis movement assembly (59) is mounted on the movable assembly (58).

6. The wafer alignment apparatus of claim 5, wherein In the X-axis direction, the first guide rail part (55) comprises a first inner side surface facing the side of the top plate (583) of the movable assembly (58), the air foot assembly further comprises a third air cushion and a third pre-tightening part in driving connection, the third air cushion is arranged on one of the first inner side surface and the movable assembly (58), and the third pre-tightening part can drive the third air cushion to move, so as to provide a force for the third air cushion to tightly press the other one of the first inner side surface and the movable assembly (58); And / or, in the X-axis direction, the first guide rail part (55) comprises a second inner side surface opposite to the first inner side surface, the air foot assembly further comprises a third positive pressure part arranged on the second inner side surface or the movable assembly (58), and the third positive pressure part and the third air cushion cooperate to provide guidance for movement of the movable assembly (58) in the Y-axis direction; And / or, in the X-axis direction, the first guide rail part (55) further comprises a second inner side surface opposite to the first inner side surface, the air foot assembly further comprises a third vacuum part arranged on the second inner side surface or the movable assembly (58), and the third vacuum part can generate negative pressure to adsorb and fix the first guide rail part (55) on the movable assembly (58).

7. The wafer alignment apparatus of claim 5, wherein The top plate (583) of the movable assembly (58) is provided with a groove extending in the Y direction; in the X-axis direction, the groove comprises a third inner side surface and a fourth inner side surface; In the X-axis direction, the first guide rail part comprises a first outer side surface facing the third inner side surface, and the air foot assembly further comprises a fourth air cushion and a fourth pre-tightening member in driving connection, the fourth air cushion is arranged on one of the third inner side surface and the first outer side surface, and the fourth pre-tightening member can drive the fourth air cushion to move to provide a force to tightly press the other one of the third inner side surface and the first outer side surface for the fourth air cushion; In the X-axis direction, the first guide rail part further comprises a second outer side surface opposite to the first outer side surface, and the second outer side surface faces the fourth inner side surface; the air foot assembly further comprises a fourth positive pressure part arranged on the second outer side surface or the fourth inner side surface, and the fourth positive pressure part can cooperate with the fourth air cushion to provide guidance for movement of the movable assembly (58) in the Y-axis direction; In the X-axis direction, the first guide rail part further comprises a second outer side surface opposite to the first outer side surface, and the second outer side surface faces the fourth inner side surface; the air foot assembly further comprises a second vacuum part arranged on the second outer side surface or the fourth inner side surface, and the second vacuum part can generate negative pressure to adsorb and fix the first guide rail part on the movable assembly.

8. The wafer alignment apparatus of any one of claims 5 to 7, wherein, The first visual inspection system (5) further comprises an X-axis movement assembly, the X-axis movement assembly comprises an X-axis guide rail part (50) and a second driving part, the X-axis guide rail part (50) is arranged on the first mounting frame (4) and extends in the X-axis direction, the second driving part comprises a first stator part (54) and a first mover part, the first stator part (54) is arranged on the first mounting frame (4) and is in driving connection with the first mover part, and the first mover part and the X-axis guide rail part (50) are in sliding cooperation; the movable assembly (58) is arranged on the first mover part, and the first mover part can drive the movable assembly (58) to move in the X-axis direction along the first cross beam (41).

9. The wafer alignment apparatus of claim 8, wherein, The first guide rail part is connected with the first mover part and is arranged on the movable assembly (58).

10. The wafer alignment apparatus of claim 8, wherein, The Y-axis movement assembly comprises a first driving part (57), the first driving part (57) comprises a second stator part (571) and a second mover part (572), the second stator part (571) is arranged on the first guide rail part, the second mover part (572) is arranged on a top plate (583) above the first cross beam (41), and the second stator part (571) is in driving cooperation with the second mover part (572).

11. The wafer alignment device of claim 1, wherein, The wafer alignment device further comprises a second visual inspection system (6), the second visual inspection system (6) is arranged in correspondence with the first visual inspection system (5) in the Z-axis direction and is located below the lower wafer movement system.

12. The wafer alignment device of claim 1, wherein, The upper wafer carrier (21) is provided with a detection hole (22), and the first visual inspection system (5) can detect alignment marks on the lower wafer on the lower wafer carrier (31) through the detection hole (22).

13. The wafer alignment device of claim 1, wherein, a first detection position and a first wafer loading position are provided corresponding to the upper wafer; the upper wafer is loaded onto the upper wafer carrier (21) at the first wafer loading position, and alignment mark detection is performed on the upper wafer at the first detection position; a second detection position and a second wafer loading position are provided corresponding to the lower wafer; the lower wafer is loaded onto the lower wafer carrier (31) at the second wafer loading position, and alignment mark detection is performed on the lower wafer at the second detection position; when the upper wafer is at the first wafer loading position, the center line of the upper wafer along the Z-axis direction is a first Z-direction center line; when the upper wafer is at the first detection position, the center line of the upper wafer along the Z-axis direction is a second Z-direction center line; when the lower wafer is at the second wafer loading position, the center line of the lower wafer along the Z-axis direction is a third Z-direction center line; when the lower wafer is at the second detection position, the center line of the lower wafer along the Z-axis direction is a fourth Z-direction center line; the first Z-direction center line, the second Z-direction center line, the third Z-direction center line, and the fourth Z-direction center line coincide.

14. An alignment method of aligning an upper wafer and a lower wafer based on the wafer alignment apparatus according to any one of claims 1 to 13, characterized by, including: a first detection position and a first wafer loading position are provided corresponding to the upper wafer; the upper wafer is loaded onto the upper wafer carrier (21) at the first wafer loading position, and alignment mark detection is performed on the upper wafer at the first detection position; a second detection position and a second wafer loading position are provided corresponding to the lower wafer; the lower wafer is loaded onto the lower wafer carrier (31) at the second wafer loading position, and alignment mark detection is performed on the lower wafer at the second detection position; when the upper wafer is at the first wafer loading position, the center line of the upper wafer along the Z-axis direction is a first Z-direction center line; when the upper wafer is at the first detection position, the center line of the upper wafer along the Z-axis direction is a second Z-direction center line; when the lower wafer is at the second wafer loading position, the center line of the lower wafer along the Z-axis direction is a third Z-direction center line; when the lower wafer is at the second detection position, the center line of the lower wafer along the Z-axis direction is a fourth Z-direction center line; the first Z-direction center line, the second Z-direction center line, the third Z-direction center line, and the fourth Z-direction center line coincide. the upper wafer carrier (21) and the lower wafer carrier (31) are loaded with the upper wafer and the lower wafer, respectively; a first visual detection system performs alignment mark detection on the upper wafer and the lower wafer, respectively.

15. An alignment method of aligning an upper wafer and a lower wafer based on the wafer alignment apparatus according to any one of claims 1 to 13, characterized by, including: a first detection position and a first wafer loading position are provided corresponding to the upper wafer; the upper wafer is loaded onto the upper wafer carrier (21) at the first wafer loading position, and alignment mark detection is performed on the upper wafer at the first detection position; a second detection position and a second wafer loading position are provided corresponding to the lower wafer; the lower wafer is loaded onto the lower wafer carrier (31) at the second wafer loading position, and alignment mark detection is performed on the lower wafer at the second detection position; when the upper wafer is at the first wafer loading position, the center line of the upper wafer along the Z-axis direction is a first Z-direction center line; The upper wafer is at the first detection position, and a center line of the upper wafer along the Z-axis direction is a second Z-direction center line; The lower wafer is at the second wafer loading position, and a center line of the lower wafer along the Z-axis direction is a third Z-direction center line; The lower wafer is at the second detection position, and a center line of the lower wafer along the Z-axis direction is a fourth Z-direction center line; The first Z-direction center line, the second Z-direction center line, the third Z-direction center line and the fourth Z-direction center line coincide; The upper wafer loading plate (21) and the lower wafer loading plate (31) load the upper wafer and the lower wafer respectively; The first visual detection system detects the alignment mark of the upper wafer; The second visual detection system detects the alignment mark of the lower wafer.

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