Wafer centering and edge searching mechanism

Abstract

The wafer centering and edge searching mechanism is characterized in that an upper-layer plate is fixed above a base, and a motor drives a slide holder to rotate; the lower-layer plate is located below the upper-layer plate and installed on the base, and the lower-layer plate and the guide columns are assembled in a sliding mode; the air cylinder drives the lower-layer plate to ascend and descend along the guide columns. The bottom of the top shaft is fixed on the lower-layer plate, and the top passes through the upper-layer plate and surrounds the outer side of the slide holder; the pair of cam bearings are symmetrically installed on the edges of the two sides of the lower layer plate, the pair of clamping discs are symmetrically arranged on the two sides of the slide holder, and the pair of cam bars are vertically and symmetrically arranged at the bottoms of the pair of clamping discs; in the lifting process of the lower-layer plate, under the action of the compression spring, the cam strip is always in close fit with the cam bearing to drive the pair of clamping discs to move in the same direction or in the opposite directions; the two optical fiber sensors are respectively used for sensing the wafer on the slide holder and sensing the flat edge of the wafer. According to the utility model, the edge searching and aligning precision of the wafer is improved, the action is simple, the design cost is low, and convenience is provided for the manufacturing of semiconductors.

Description

Technical Field

[0001] The utility model relates to the technical field of semiconductor manufacturing, and specifically relates to a wafer centering and edge-finding mechanism. Background Art

[0002] In the process of semiconductor manufacturing, the outer edge of a wafer is designed with a flat edge as a positioning mark, which can be used to determine the orientation of the wafer in subsequent processing to identify the chip position and direction of the wafer and ensure the consistency of front and back processing. The current wafer flat-edge finding device has a complex structure, cumbersome operations, high design costs, and is prone to damage the wafer. Summary of the Utility Model

[0003] The purpose of the utility model is to provide a wafer centering and edge-finding mechanism aiming at the deficiencies of the above-mentioned existing technologies, so as to realize the center alignment and flat-edge alignment of the wafer and improve the accuracy of wafer edge-finding and alignment.

[0004] The technical solution of the utility model is as follows:

[0005] The wafer centering and edge-finding mechanism is characterized by including a centering unit, a lifting unit, a rotating unit, and a photoelectric sensor; the rotating unit includes a motor, an upper layer board, a wafer carrier, and support columns. The upper layer board is installed and fixed above the base through multiple support columns. The motor is installed on the upper layer board and is used to drive the rotation of the wafer carrier.

[0006] The lifting unit includes a cylinder, a lower layer board, guide columns, and a top shaft; the lower layer board is located below the upper layer board and is installed on the base through multiple guide columns, and the lower layer board is slidably assembled with the guide columns; the cylinder is installed on the base, and its output shaft is connected to the bottom of the lower layer board to drive the lower layer board to move up and down along the guide columns; the bottoms of multiple top shafts are fixed to the lower layer board, and their tops pass through the upper layer board and surround the outside of the wafer carrier.

[0007] The centering unit includes a pair of clamping disks, a pair of sliding components, a pair of cam strips, a pair of cam bearings, and a compression spring; a pair of cam bearings are symmetrically installed on the two side edges of the lower layer board, a pair of clamping disks are symmetrically arranged on both sides of the wafer carrier, and a pair of cam strips are vertically and symmetrically arranged at the bottoms of the pair of clamping disks; during the process of the cylinder driving the lower layer board to move up and down, under the action of the compression spring, the cam structures of the cam strips are always in close contact with the cam bearings, driving the pair of clamping disks to move towards or away from each other along the corresponding sliding components.

[0008] The photoelectric sensor includes: a first fiber optic sensor for sensing whether there is a wafer on the wafer carrier; a second fiber optic sensor for sensing the flat edge of the wafer. If the flat edge is not in the positioning position, the plane structure of the wafer will block the light of the second fiber optic sensor. If the flat edge is in the positioning position, the light of the second fiber optic sensor is tangent to the flat edge of the wafer.

[0009] When the utility model is in use: when the lifting cylinder is in a fully raised state, the lower layer plate is at a high position, and multiple top shafts are higher than the wafer stage; during this process, through the cam structure design of the cam bar, the compression spring is in a heavy compression state, and under the action of the spring force, the cam bar is in close contact with the cam bearing. A pair of clamping disks move parallel with the cam bar and are in an outward-opening state. A 6-inch wafer is placed on the top of the top shaft, and the top shaft can move up and down with the cylinder;

[0010] When the lifting cylinder is in a descending state and not fully descended, about 2 / 3 of the stroke is descended, and 1 / 3 of the stroke remains. The lower layer plate is in the middle position, and the 6-inch wafer disengages from the top shaft and falls on the wafer stage. At this time, the compression spring is in a light compression state, and a pair of clamping disks move parallel with the cam bar and move towards each other, performing a clamping action on the 6-inch wafer to complete wafer centering;

[0011] When the lifting cylinder is in a fully descended state and the lower layer plate is at a low position, at this time the compression spring is in a medium compression state, and a pair of clamping disks move parallel with the cam bar and move away from each other, slightly away from the 6-inch wafer and no longer in contact with the wafer. The motor drives the wafer stage to rotate, and then drives the 6-inch wafer to rotate; when the light of the fiber optic sensor that senses the flat edge of the wafer is not blocked, the flat edge finding action is completed and the motor stops rotating.

[0012] Further, in order to enable a pair of clamping disks to move towards or away from each other smoothly, the sliding component includes a pair of guide rods and a pair of centering sliders. The pair of guide rods are horizontally and parallelly arranged along the movement direction of the clamping disks. The pair of centering sliders are respectively installed at the bottom of the pair of clamping disks, and the centering sliders are sleeved on the guide rods and are in sliding fit with the guide rods. The top of the cam bar is fixedly installed at the middle position of the centering sliders.

[0013] Further, in order to achieve wafer centering and reduce the contact area with the wafer, two symmetrically arranged clamping blocks are respectively provided on the upper surface of each clamping disk. The inner side surface of each clamping block is an arc surface matching the wafer. The four clamping blocks center the wafer from four points on the side of the wafer, reducing the contact area and improving the centering accuracy.

[0014] Further, in order to make the cam bearing always closely fit with the cam bar during the rising process, the compression spring is sleeved on the guide rod and tightly presses the centering slider. There are four compression springs, which are respectively located between the centering slider and the mechanism side plate, always keeping the centering slider tightly pressed to ensure the contact between the cam bearing and the cam bar.

[0015] Furthermore, in order to achieve the three actions of the clamping plate in the middle unit, an innovative design is made for the cam structure of the cam bar: the cam structure of the cam bar is arranged on the inner side surface and includes a relatively wide vertical surface, a concave curved surface, and a relatively narrow vertical surface that are connected in sequence from top to bottom; the thickness of the cam bar on the relatively wide vertical surface is greater than that on the relatively narrow vertical surface, and the thickness of the cam bar on the relatively narrow vertical surface is greater than that on the concave curved surface. By setting three different thicknesses, the displacement state of a pair of clamping plates is changed.

[0016] During the process of the air cylinder driving the lower layer plate to lift and lower, the compression spring tightly presses the centering slider, so that the cam bearing and the cam bar are respectively in cooperation with the relatively wide vertical surface (the lower layer plate is in the high position), the concave curved surface (the lower layer plate is in the middle position), and the relatively narrow vertical surface (the lower layer plate is in the low position), realizing the clamping or separating action of a pair of clamping plates.

[0017] Furthermore, the output shaft of the air cylinder is connected to the central position of the lower layer plate to make the operation of the lower layer plate more stable; the motor is driven to connect the wafer stage through a belt.

[0018] The utility model has a simple structure, is easy to manufacture, realizes the center alignment and flat edge alignment of the wafer, improves the accuracy of wafer edge finding and alignment, is stable and reliable, has simple actions, and has a low design cost, providing convenience for the manufacture of semiconductors. Description of the Drawings

[0019] Figure 1 is the front view of the utility model (the lower layer plate is in the high position);

[0020] Figure 2 is Figure 1 the sectional view taken along the R-R direction in

[0021] Figure 3 is Figure 1 the three-dimensional view of

[0022] Figure 4 is Figure 1 the top view of

[0023] Figure 5 is the front view of the utility model (the lower layer plate is in the middle position);

[0024] Figure 6 is Figure 5 the top view of

[0025] Figure 7 is the front view of the utility model (the lower layer plate is in the low position);

[0026] Figure 8 is Figure 7 the top view of

[0027] Figure 9Internal structure schematic diagram of the removal mechanism side plate of the present utility model (the lower layer plate is at a high position);

[0028] In the figure: motor 1, upper layer plate 2, wafer stage 3, support column 4, base 5, cylinder 6, lower layer plate 7, guide post 8, top shaft 9, clamping disc 10, cam bar 11, cam bearing 12, compression spring 13, clamping block 14, wider vertical surface 15, concave curved surface 16, narrower vertical surface 17, guide rod 18, centering slider 19, first fiber optic sensor 20, second fiber optic sensor 21, wafer 22. Detailed implementation manners

[0029] The wafer centering and edge finding mechanism, as shown in the figure, includes a centering unit, a lifting unit, a rotating unit, and a photoelectric sensor, where:

[0030] 1. Rotating unit

[0031] The rotating unit includes a motor 1, an upper layer plate 2, a wafer stage 3, and a support column 4. The upper layer plate is installed and fixed above the base 5 through three support columns. The motor is installed on the upper layer plate, and the output shaft of the motor drives and connects the wafer stage through a belt to drive the rotation of the wafer stage.

[0032] 2. Lifting unit

[0033] The lifting unit includes a cylinder 6, a lower layer plate 7, guide posts 8, and a top shaft 9. The lower layer plate is installed on the base through a pair of guide posts. The cylinder drives the lower layer plate to perform lifting actions along the guide posts. The bottom of the top shaft is fixed to the lower layer plate, and its top passes through the upper layer plate and surrounds the outside of the wafer stage for carrying the wafer.

[0034] 3. Centering unit

[0035] The centering unit includes a pair of clamping discs 10, a pair of sliding components, a pair of cam bars 11, a pair of cam bearings 12, and four compression springs 13. A pair of cam bearings are symmetrically installed on the two side edges of the lower layer plate and move up and down with the lower layer plate. A pair of clamping discs are symmetrically arranged on both sides of the wafer stage. On the upper surface of each clamping disc, two symmetrically arranged clamping blocks 14 are respectively provided. The inner side surface of each clamping block is an arc surface matching the wafer. A pair of cam bars are vertically and symmetrically arranged at the bottom of a pair of clamping discs. The cam structure of the cam bar is arranged on the inner side surface and includes a wider vertical surface 15, a concave curved surface 16, and a narrower vertical surface 17 connected in sequence from top to bottom. The thickness of the cam bar on the wider vertical surface is greater than that on the narrower vertical surface, and the thickness of the cam bar on the narrower vertical surface is greater than that on the concave curved surface.

[0036] The sliding assembly includes a pair of guide rods 18 and a pair of centering sliders 19. The centering sliders are sleeved on the guide rods and are in sliding fit with the guide rods. The top of the cam strip is fixedly installed at the middle position of the centering slider. Four compression springs are sleeved on the guide rods and are respectively located between the centering slider and the mechanism side plate, always pressing tightly on the centering slider to ensure that the cam bearing contacts the inner side surface of the cam strip.

[0037] 4. Photoelectric sensor

[0038] The photoelectric sensor includes a first fiber optic sensor 20 and a second fiber optic sensor 21. The first fiber optic sensor is used to sense whether there is a wafer on the carrier stage, and the second fiber optic sensor is used to sense the flat edge of the wafer: that is, if the flat edge is not in the positioning position, the planar structure of the wafer will block the light of the second fiber optic sensor, and if the flat edge is in the positioning position, the light of the second fiber optic sensor will be tangent to the flat edge of the wafer.

[0039] The working process of the wafer centering and edge finding mechanism is as follows:

[0040] 1) When the lifting cylinder is in the fully raised state, the lower layer plate is at a high position, and the tops of the three jack shafts are higher than the carrier stage; the cam bearing rises with the lower layer plate, and the compression spring is in a heavily compressed state. Under the action of the spring force, the cam bearing is closely attached to the wider vertical surface of the cam strip. A pair of clamping plates move parallel with the cam strip and are in an outward-opening state. A 6-inch wafer is placed on the tops of the jack shafts.

[0041] 2) The lifting cylinder is in the descending state and has not descended completely, descending about 2 / 3 of the stroke, with 1 / 3 of the stroke remaining. The lower layer plate is in the middle position. The 6-inch wafer disengages from the jack shafts and lands on the carrier stage; the cam bearing descends with the lower layer plate, and the compression spring is in a lightly compressed state. Under the action of the spring force, the cam bearing is closely attached to the concave curved surface of the cam strip. A pair of clamping plates move parallel with the cam strip and move towards each other, performing a clamping action on the 6-inch wafer to complete wafer centering and alignment.

[0042] 3) The lifting cylinder is in the fully lowered state, and the lower layer plate is at a low position. The cam bearing continues to descend with the lower layer plate. At this time, the compression spring is in a medium-compressed state. Under the action of the spring force, the cam bearing is closely attached to the narrower vertical surface of the cam strip. A pair of clamping plates move parallel with the cam strip and move away from each other, slightly away from the 6-inch wafer and no longer in contact with the wafer. The motor drives the carrier stage to rotate, and then drives the 6-inch wafer to rotate; when the light emitted by the second fiber optic sensor that senses the flat edge of the wafer is not blocked, the flat edge finding action is completed, and the motor stops rotating.

Claims

1. Wafer centering and edge finding mechanism, which is characterized by: It includes a centering unit, a lifting unit, a rotating unit, and a photoelectric sensor; the rotating unit includes a motor, an upper plate, a wafer stage, and a supporting column, the upper plate is fixed on the top of the base through a plurality of supporting columns, and the motor is installed on the upper plate to drive the rotation of the wafer stage; The lifting unit includes a cylinder, a lower plate, a guide column, and a top shaft; the lower plate is located below the upper plate and is mounted on the base through a plurality of guide columns, and the lower plate and the guide columns are slidably assembled; the cylinder is mounted on the base, and its output shaft is connected to the bottom of the lower plate to drive the lower plate to move up and down along the guide columns; the bottoms of the plurality of top shafts are fixed to the lower plate, and the tops thereof pass through the upper plate and surround the outer side of the carrier stage; The centering unit comprises a pair of clamping plates, a pair of sliding assemblies, a pair of cam strips, a pair of cam bearings, and a compression spring; the pair of cam bearings are symmetrically installed on the two side edges of the lower plate, the pair of clamping plates are symmetrically arranged on the two sides of the wafer stage, and the pair of cam strips are vertically and symmetrically arranged on the bottom of the pair of clamping plates; during the process of the cylinder driving the lower plate to rise and fall, under the action of the compression spring, the cam structure of the cam strip is always in close contact with the cam bearing, driving the pair of clamping plates to move toward or away from each other along the corresponding sliding assemblies; The photoelectric sensor includes two optical fiber sensors, which are respectively used for sensing the wafer on the wafer stage and sensing the flat edge of the wafer.

2. The wafer centering and edge finding mechanism according to claim 1, characterized in that: The sliding assembly includes a pair of guide rods and a pair of centering sliders. The pair of guide rods are arranged horizontally and in parallel. The pair of centering sliders are respectively installed at the bottom of a pair of clamping plates, and the centering sliders are sleeved on the guide rods and slidably matched with the guide rods.

3. The wafer centering and edge finding mechanism according to claim 2, characterized in that: The upper surface of each clamping plate is provided with two symmetrically arranged clamping blocks, and the inner side surface of each clamping block is an arc surface matching the wafer.

4. The wafer centering and edge finding mechanism according to claim 3, characterized in that: The compression spring is sleeved on the guide rod and presses the centering slide block tightly.

5. The wafer centering and edge finding mechanism according to claim 4, characterized in that: The cam structure of the cam strip is arranged on the inner side surface, including a wider vertical surface, a concave curved surface, and a narrower vertical surface which are connected in sequence from top to bottom; the thickness of the cam strip on the wider vertical surface is greater than the thickness on the narrower vertical surface, and the thickness of the cam strip on the narrower vertical surface is greater than the thickness on the concave curved surface; when the cylinder drives the lower plate to rise and fall, the compression spring presses the centering slider tightly, so that the cam bearing and the cam strip cooperate on the wider vertical surface, the concave curved surface, and the narrower vertical surface respectively, so as to realize a pair of clamping disks to perform clamping or separation actions.

6. The wafer centering and edge finding mechanism according to claim 1, characterized in that: The output shaft of the cylinder is connected to the center position of the lower plate, and the motor is connected to the wafer carrier through a belt drive.

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