A liftable stage and a method for detecting epitaxial wafer using the stage

Abstract

A liftable stage comprises a frame, a wafer stage (20), a pin assembly, a lifting mechanism, and a driving assembly; the driving assembly is characterized in that the driving assembly can drive the wafer stage (20) to lift and lower through the lifting mechanism, so that the top of the pin (12) in the pin assembly is in a position protruding from the upper surface of the wafer stage (20) by a certain distance, flush with the upper surface of the wafer stage (20), or lower than the upper surface of the wafer stage (20) by a certain distance; when the top of the pin (12) is in a position protruding from the upper surface of the wafer stage (20) by a certain distance, automatic placement and removal of epitaxial wafers can be achieved; when the top of the pin (12) is in a position flush with the upper surface of the wafer stage (20), or lower than the upper surface by a certain distance, adsorption and fixation of the epitaxial wafer can be achieved, as well as automatic focusing during detection.

Description

Technical Field

[0001] The invention relates to a liftable loading platform used for detecting epitaxial wafers, belonging to the technical field of epitaxial wafer detection. Background Art

[0002] In recent years, the prosperity of the downstream application market has driven the rapid development of my country's LED industry, and the epitaxial wafer market has also ushered in a good opportunity for development. The domestic LED epitaxial wafer production capacity has increased rapidly, and the technical level has continued to improve. Epitaxial wafers are front-end high-tech products among LED core components. Therefore, epitaxial wafer inspection equipment needs to be fast, effective, and low-cost. For the stage on the automatic epitaxial wafer inspection equipment, it is necessary to more flexibly adjust the lifting to the best inspection position and the best position for the robot to pick up and place the wafer.

[0003] The existing epitaxial wafer detection device adopts a cross roller guide type slide, as shown in the attached Figure 1 As shown. Its basic structure is: a coupling 002 is provided on the output shaft of the driving motor 001, the lead screw 003 is connected to the driving motor 001 through the coupling 002, and the cross roller type slide contains three sets of cross roller guides, namely the XZ cross roller guide 006, the X cross roller guide 005, and the Z cross roller guide 004 along the inclined surface. The inclined platform 009 is fixed on the lead screw nut 007. As the lead screw 003 rotates, the lead screw nut 007 drives the inclined platform 009 to move left and right along the X cross roller guide 005 and the XZ cross roller guide 006, and the inclined platform 009 drives the lifting block 010 to move up and down along the XZ cross roller guide 006 and the Z cross roller guide 004. Compared with the present invention, the cross roller slide has high machining accuracy requirements, difficult machining, and high machining costs; the cylindrical roller itself is relatively large (proportional) and has a small lifting stroke; the cross roller guide rail has weak impact resistance, and will cause sliding abnormalities if it falls or too much force is applied to it. Before it is reliably installed and fixed, the roller retainer assembly may fall when subjected to external force, which requires special attention during use, making installation more difficult. The slide has high machining and installation accuracy requirements, is inconvenient to install, has a small Z-axis lifting stroke, and is not cost-effective.

[0004] The lifting block 010 of the slide is provided with a loading platform 011, and the center of the loading platform 011 has a groove for the robot to take and place the slice, as shown in the attached Figure 2 As shown in the figure, the groove is the position where the robot can reach in and out to pick up and place the wafer. If there is no groove, the robot cannot pick up and place the wafer. The stage with grooves will cause the epitaxial wafer adsorption surface to be non-flat, thereby affecting the effect of epitaxial wafer adsorption and fixation. At the same time, it will also make the background inconsistent when the transparent epitaxial wafer is detected, thereby affecting the accuracy of the detection. Summary of the invention

[0005] The purpose of the present invention is to provide an automatically lifting stage to address the above-mentioned problems existing in the prior art. By lifting the stage to different positions, a robot can automatically take and place epitaxial wafers, detect background consistency, and automatically adjust the position to achieve focusing.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] A liftable stage comprises a frame, a wafer stage, an ejector pin assembly, a lifting mechanism, and a driving assembly; the driving assembly can drive the wafer stage to rise and fall through the lifting mechanism, so that the top of the ejector pin in the ejector pin assembly is at a position protruding from the upper surface of the wafer stage by a certain distance, flush with the upper surface of the wafer stage, or lower than the upper surface of the wafer stage by a certain distance; when the top of the ejector pin is at a position protruding from the upper surface of the wafer stage by a certain distance, automatic placement and removal of epitaxial wafers can be achieved; when the top of the ejector pin is at a position flush with the upper surface of the wafer stage, or lower than the upper surface by a certain distance, adsorption and fixation of the epitaxial wafer can be achieved, as well as automatic focusing during detection.

[0008] Preferably, the driving assembly includes a motor and a coupling, and the lifting mechanism is drivingly connected to the output shaft of the motor via the coupling.

[0009] Preferably, the lifting mechanism includes a screw, a screw support, a screw nut, a slider push plate, an idler wheel, an idler wheel support, and a Z-axis upper plate; the screw is rotatably arranged on the screw seat, the screw seat is fixed on the screw support, the screw support is fixed on the Z-axis bottom plate, one end of the screw is drivingly connected to the output shaft of the motor through a coupling, and the other end is sleeved with a screw nut; the slider push plate is fixedly connected to the screw nut, the idler wheel abuts against the inclined surface of the slider push plate and can slide along the inclined surface, the idler wheel is slidably connected to the frame through the idler wheel support, and can slide up and down along the frame; the Z-axis upper plate is arranged on the top of the idler wheel support, and the top of the Z-axis upper plate is fixedly connected to the carrier stage.

[0010] Preferably, the ejector assembly includes an ejector, an ejector support, and an ejector fixing plate. The ejector support is fixed to the Z-axis bottom plate of the frame, the ejector fixing plate is fixed to the ejector support, and the ejector is fixed to the ejector fixing plate and can pass through the corresponding through hole on the wafer carrier.

[0011] Preferably, there are three ejector pins, which are evenly distributed along the circumferential direction, and the top ends of all the ejector pins are located in the same horizontal plane.

[0012] Preferably, a horizontal guide rail is also provided on the Z-axis bottom plate, and the slider push plate is provided on the horizontal guide rail and can move left and right along the horizontal guide rail.

[0013] Preferably, a Z-rail extending in the vertical direction is also provided on the Z-axis base plate, and the Z-axis guide rail plate is slidably arranged on the Z-rail, the Z-axis guide rail plate is fixedly connected to the Z-axis upper plate, and the idler wheel support is fixedly connected to the Z-axis upper plate, so that the idler wheel can drive the idler wheel support, the Z-axis upper plate, and the Z-axis guide rail plate to slide up and down along the Z-axis guide rail.

[0014] Preferably, a tension spring is provided between the Z-axis upper plate and the Z-axis bottom plate, and the tension spring provides a tension force to move the Z-axis upper plate downward.

[0015] In addition, the present invention also relates to a method for detecting an epitaxial wafer using a liftable stage, comprising the following steps:

[0016] Step 1: Turn on the drive assembly, drive the wafer stage downward through the lifting mechanism, so that the top of the ejector pin in the ejector pin assembly is at a position protruding a certain distance from the upper surface of the wafer stage, and stop driving;

[0017] Step 2: Drive the manipulator to automatically place the epitaxial wafer to be tested on the ejector pin;

[0018] Step 3: Turn on the drive assembly, drive the wafer stage upward through the lifting mechanism, so that the top of the ejector pin in the ejector pin assembly does not protrude from the upper surface of the wafer stage, and stop driving;

[0019] Step 4: Use negative pressure to fix the epitaxial wafer on the wafer stage;

[0020] Step 5: Turn on the detection system to determine whether the epitaxial wafer is in the best focus position for detection. If not, continue to turn on the drive assembly to drive the wafer stage to move upward, and automatically determine the position of the epitaxial wafer until the epitaxial wafer is in the best focus position, stop driving, and start detection;

[0021] Step 6: After the detection is completed, the driving assembly is turned on, and the wafer stage is driven downward by the lifting mechanism, so that the top of the ejector pin in the ejector pin assembly is at a position protruding a certain distance from the upper surface of the wafer stage, and the driving is stopped;

[0022] Step 7: Drive the robot to take away the epitaxial wafer after inspection.

[0023] Preferably, in the detection method:

[0024] Step 1 is as follows: the drive motor rotates counterclockwise, driving the lead screw to rotate counterclockwise, the lead screw nut moves to the right, the slider push plate moves to the right on the horizontal guide rail along with the lead screw nut, the tension spring drives the Z-axis upper plate to move downward, the idler wheel keeps in contact with the inclined surface of the slider push plate, the Z-axis guide plate slides downward along the Z guide rail, the carrier moves downward, the ejector pin protrudes a certain distance outside the carrier, and when the ejector pin exceeds the upper surface of the carrier to a predetermined value, the motor stops rotating;

[0025] Step three is specifically as follows: the drive motor rotates clockwise, the motor drives the lead screw to rotate clockwise, the lead screw nut moves to the left, the slider push plate moves to the left on the horizontal guide rail along with the lead screw nut, the slider push plate inclined surface pushes the idler wheel to move upward, the idler wheel drives the idler wheel support, the Z-axis upper plate, and the wafer carrier to move upward, and at the same time the tension spring is stretched, the Z-axis guide plate slides upward along the Z guide rail, and the wafer carrier moves upward until the top of the ejector pin does not protrude from the upper surface of the wafer carrier, so that the epitaxial wafer contacts the upper surface of the wafer carrier.

[0026] The stage lifting mechanism of the present invention is flexible to adjust, easy to install, cost-effective, and applicable to narrow spaces. By providing an ejector assembly and a liftable stage, it is possible to automatically take and place a film, automatically adjust the focus position, and improve the detection accuracy simply by controlling the lifting of the stage. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a cross roller guide type slide in the prior art;

[0028] Figure 2 It is a schematic diagram of a stage with grooves in the prior art;

[0029] Figure 3 An exploded perspective view of the liftable loading platform of the present invention;

[0030] Figure 4 This is a schematic diagram of the working principle of the stage;

[0031] Figure 5 The front view of the present application is to place the epitaxial wafer on the wafer stage;

[0032] Figure 6 It is the main view of the present application when the epitaxial wafer is located at the detection position;

[0033] Figure 7 It is a partial cross-sectional view when the ejector pin is flush with the surface of the wafer stage;

[0034] Figure 8 This is a partial cross-sectional view when the ejector pin is lower than the upper surface of the wafer stage.

[0035] 001. Drive motor 002. Coupling 003. Screw 004. Z cross roller guide 005. X cross roller guide 006. XZ cross roller guide 007. Screw nut 008. Base 009. Inclined table 010. Lifting block 011. Groove stage 012. Manipulator 013. Epitaxial wafer 1. Motor 2. Coupling 3. Screw seat 4. Screw support 5. Screw 6. Slider push plate 7. Screw nut 8. Horizontal guide 9. Z axis bottom plate 10. Z guide 11. Z axis guide plate 12. Ejector 13. Ejector support 14. Ejector fixing plate 15. Tension spring 16. Tension spring nail 17. Idle wheel support 18. Idle wheel 19. Z axis upper plate 20. Wafer stage 21. Epitaxial wafer DETAILED DESCRIPTION

[0036] See attached Figure 3-8 The liftable stage in the present application comprises a frame, a wafer carrier 20, a pin assembly, a lifting mechanism, and a driving assembly.

[0037] The frame includes a Z-axis base plate 9 (other parts are not shown in the drawings), and the driving assembly includes a motor 1 and a coupling 2. The motor 1 is fixedly arranged on the frame, and the coupling 2 is arranged on the output shaft of the motor 1.

[0038] The lifting mechanism includes a screw 5, a screw seat 3, a screw support 4, a screw nut 7, a slider push plate 6, an idler wheel 18, an idler wheel support 17, and a Z-axis upper plate 19; the screw 5 is rotatably arranged on the screw seat 3, the screw seat 3 is fixed on the screw support 4, the screw support 4 is fixed on the Z-axis bottom plate 9, one end of the screw 5 is drivingly connected to the output shaft of the motor 1 through the coupling 2, and the other end is provided with a screw nut 7; the slider push plate 6 is fixedly connected to the screw nut 7, the idler wheel 18 abuts against the inclined surface of the slider push plate 6 and can slide along the inclined surface, the idler wheel 18 is slidably connected to the frame through the idler wheel support 17, and can slide up and down along the frame; the Z-axis upper plate 19 is arranged on the top of the idler wheel support 17, and the film carrier 20 is arranged on the top of the Z-axis upper plate 19.

[0039] The ejector assembly includes an ejector 12, an ejector support 13, and an ejector fixing plate 14. The ejector support 13 is fixed on the Z-axis bottom plate 9 of the frame, the ejector fixing plate 14 is fixed on the ejector support 13, and the ejector 12 is fixed on the ejector fixing plate 14 and passes through the corresponding through hole on the wafer stage 20. The ejector 12 is preferably 3 and evenly distributed along the circumferential direction. The tops of all ejector pins 12 are located on the same horizontal plane.

[0040] The driving assembly can drive the stage to rise and fall through the lifting mechanism, so that the top of the ejector pin 12 in the ejector pin assembly is at a position protruding from the upper surface of the stage 20 by a certain distance, flush with the upper surface of the stage 20, or lower than the upper surface of the stage 20 by a certain distance. When the top of the ejector pin 12 is at a position protruding from the stage 20 by a certain distance, automatic placement and removal of the epitaxial wafer can be achieved; when the top of the ejector pin 12 is at a position flush with the upper surface of the stage 20, or lower than the upper surface by a certain distance, adsorption and fixation of the epitaxial wafer can be achieved, as well as automatic focusing during detection.

[0041] In another embodiment, a horizontal guide rail 8 may be further provided on the Z-axis base plate 9 , and the slider push plate 6 is provided on the horizontal guide rail 8 and can move left and right along the horizontal guide rail 8 .

[0042] In another embodiment, a Z-rail 10 extending in the vertical direction is further provided on the Z-axis bottom plate 9, a Z-rail plate 11 is slidably provided on the Z-rail 10, the Z-rail plate 11 is connected to the Z-axis upper plate 19, and the idler support 17 is fixedly connected to the Z-axis upper plate 19. Thus, the idler 18 can drive the idler support 17, the Z-axis upper plate 19, and the Z-rail plate 11 to slide up and down along the Z-axis rail 10.

[0043] In another embodiment, a tension spring 15 is disposed between the Z-axis upper plate 19 and the Z-axis bottom plate 9 , and the tension spring 15 provides a tension force to move the Z-axis upper plate 19 downward.

[0044] When it is necessary to test the epitaxial wafer, the working steps are as follows:

[0045] Step 1: Drive motor 1 to rotate counterclockwise, drive lead screw 5 to rotate counterclockwise, lead screw nut 7 to move rightward (motor side), slider push plate 6 moves rightward (motor side) on horizontal guide rail 8 along with lead screw nut 7, tension spring 15 drives Z-axis upper plate 19 to move downward, idler wheel 18 keeps contact with the inclined surface of slider push plate 6, Z-axis guide plate 11 slides downward along Z guide rail 10, carrier 20 moves downward, ejector pin 12 is exposed outside carrier 20 for a certain distance, when ejector pin 12 exceeds the upper surface of carrier 20 by a predetermined value, motor stops. The predetermined distance value is between 5-10mm, preferably 8.7mm;

[0046] Step 2: driving the manipulator to automatically place the epitaxial wafer 21 to be inspected on the ejector pin 12;

[0047] Step 3: Drive motor 1 to rotate clockwise, motor 1 drives lead screw 5 to rotate clockwise, lead screw nut 7 moves to the left (away from the motor side), slider push plate 6 moves to the left (away from the motor side) on horizontal guide rail 8 along with lead screw nut 7, slider push plate 6 inclined surface pushes idler wheel 18 to move upward, idler wheel 18 drives idler wheel support 17, Z-axis upper plate 19, and wafer carrier 20 to move upward, while tension spring 15 stretches, Z-axis guide plate 11 slides upward along Z-guide rail 10. The wafer carrier 20 moves upward until the top of ejector pin 12 does not protrude from the upper surface of wafer carrier 20, so that epitaxial wafer 21 contacts the upper surface of wafer carrier 20;

[0048] Step 4: Start the vacuum pump to absorb and fix the epitaxial wafer 21 on the wafer stage 20;

[0049] Step 5: Start the detection system to determine whether the epitaxial wafer is in the best focus position for detection. If not, continue to drive the motor 1 to rotate clockwise to drive the wafer stage 20 to move upward, and automatically determine the position of the epitaxial wafer until the epitaxial wafer is in the best focus position, stop the motor, and start detection;

[0050] Step 6: After the detection is completed, the driving assembly is turned on, and the wafer stage 20 is driven downward by the lifting mechanism, so that the top of the ejector pin 12 in the ejector pin assembly is at a position protruding a certain distance from the upper surface of the wafer stage 20, and the driving is stopped;

[0051] Step 7: Drive the robot to take away the epitaxial wafer after inspection.

Claims

1. A liftable stage, comprising a frame, a wafer stage (20), an ejector assembly, a lifting mechanism, and a driving assembly; characterized in that: The driving assembly can drive the wafer stage (20) to rise and fall through the lifting mechanism, so that the top of the ejector pin (12) in the ejector pin assembly is located at a position protruding from the upper surface of the wafer stage (20) by a certain distance, flush with the upper surface of the wafer stage (20), or lower than the upper surface of the wafer stage (20) by a certain distance. When the top of the ejector pin (12) is located at a position protruding from the upper surface of the wafer stage (20) by a certain distance, automatic placement and removal of the epitaxial wafer can be achieved; when the top of the ejector pin (12) is located at a position flush with the upper surface of the wafer stage (20), or lower than the upper surface by a certain distance, adsorption and fixation of the epitaxial wafer can be achieved, as well as automatic focusing during detection; The lifting mechanism comprises a lead screw (5), a lead screw support (4), a lead screw nut (7), a slider push plate (6), an idler wheel (18), an idler wheel support (17), and a Z-axis upper plate (19); the lead screw (5) is rotatably arranged on the lead screw seat (3), the lead screw seat (3) is fixed on the lead screw support (4), the lead screw support (4) is fixed on the Z-axis bottom plate (9), one end of the lead screw (5) is connected to the output shaft of the motor (1) through a coupling (2) and a transmission The idler wheel (18) is slidably connected to the frame through an idler wheel support (17) and can slide up and down along the frame; a Z-axis upper plate (19) is provided on the top of the idler wheel support (17), and the top of the Z-axis upper plate (19) is fixedly connected to the slide table (20); A Z-guide rail (10) extending in the vertical direction is also arranged on the Z-axis bottom plate (9); a Z-guide rail plate (11) is slidably arranged on the Z-guide rail (10); the Z-guide rail plate (11) is fixedly connected to the Z-axis upper plate (19); an idler wheel support (17) is fixedly connected to the Z-axis upper plate (19); thereby, the idler wheel (18) can drive the idler wheel support (17), the Z-axis upper plate (19) and the Z-guide rail plate (11) to slide up and down along the Z-guide rail (10).

2. The liftable stage according to claim 1, wherein: The driving assembly comprises a motor (1) and a coupling (2), and the lifting mechanism is drivingly connected to the output shaft of the motor (1) via the coupling (2).

3. The liftable stage according to claim 2, wherein: The ejector assembly comprises an ejector (12), an ejector support (13), and an ejector fixing plate (14). The ejector support (13) is fixed on the Z-axis bottom plate (9) of the frame, the ejector fixing plate (14) is fixed on the ejector support (13), and the ejector (12) is fixed on the ejector fixing plate (14) and can pass through a corresponding through hole on the wafer carrier (20).

4. The liftable loading platform according to claim 3, wherein: There are three ejector pins (12) which are evenly distributed along the circumferential direction, and the top ends of all the ejector pins (12) are located in the same horizontal plane.

5. The liftable loading platform according to claim 4, wherein: A horizontal guide rail (8) is also arranged on the Z-axis bottom plate (9), and the slider push plate (6) is arranged on the horizontal guide rail (8) and can move left and right along the horizontal guide rail (8).

6. The liftable loading platform according to claim 5, wherein: A tension spring (15) is arranged between the Z-axis upper plate (19) and the Z-axis bottom plate (9), and the tension spring (15) provides a tension force to move the Z-axis upper plate (19) downward.

7. A method for testing an epitaxial wafer using the liftable stage according to any one of claims 1 to 6, characterized in that: The steps are as follows: The first step is to start the driving assembly, drive the wafer carrier (20) downward through the lifting mechanism, so that the top of the ejector pin (12) in the ejector pin assembly is at a position protruding a certain distance from the upper surface of the wafer carrier (20), and stop driving; Step 2: driving the manipulator to automatically place the epitaxial wafer (21) to be inspected on the ejector pin (12); Step 3: Turn on the driving assembly, drive the wafer carrier (20) upward through the lifting mechanism, so that the top of the ejector pin (12) in the ejector pin assembly does not protrude from the upper surface of the wafer carrier (20), and stop driving; Step 4: Adsorbing and fixing the epitaxial wafer (21) on the wafer carrier (20) by negative pressure; Step 5: Start the detection system to determine whether the position of the epitaxial wafer (21) is at the best focus position for detection. If not, continue to start the drive component to drive the wafer carrier (20) to move upward, and automatically determine the position of the epitaxial wafer (21) until the epitaxial wafer (21) is at the best focus position, stop driving, and start detection; Step 6: After the detection is completed, the driving assembly is turned on, and the wafer carrier (20) is driven downward by the lifting mechanism, so that the top of the ejector pin (12) in the ejector pin assembly is at a position protruding a certain distance from the upper surface of the wafer carrier (20), and the driving is stopped; Step 7: driving the manipulator to take away the epitaxial wafer (21) after the inspection.

8. The method for detecting an epitaxial wafer according to claim 7, wherein: Step 1 is specifically as follows: the driving motor (1) rotates counterclockwise, driving the lead screw (5) to rotate counterclockwise, the lead screw nut (7) moves to the right, the slider push plate (6) moves to the right on the horizontal guide rail (8) along with the lead screw nut (7), the tension spring (15) drives the Z-axis upper plate (19) to move downward, the idler wheel (18) keeps in contact with the inclined surface of the slider push plate (6), the Z-axis guide plate (11) slides downward along the Z guide rail (10), the wafer carrier (20) moves downward, the ejector pin (12) is exposed to a certain distance outside the wafer carrier (20), and when the distance of the ejector pin (12) beyond the upper surface of the wafer carrier (20) reaches a predetermined value, the motor stops; Step three is specifically as follows: the drive motor (1) rotates clockwise, the motor (1) drives the lead screw (5) to rotate clockwise, the lead screw nut (7) moves to the left, the slider push plate (6) moves to the left on the horizontal guide rail (8) along with the lead screw nut (7), the slider push plate (6) pushes the idler wheel (18) upwardly on the inclined surface, the idler wheel (18) drives the idler wheel support (17), the Z-axis upper plate (19), and the wafer carrier (20) to move upwardly, and at the same time the tension spring (15) is stretched, the Z-axis guide plate (11) slides upwardly along the Z guide rail (10), and the wafer carrier (20) moves upwardly until the top of the ejector pin (12) does not protrude from the upper surface of the wafer carrier (20), so that the epitaxial wafer (21) contacts the upper surface of the wafer carrier (20).

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