Wafer edge polishing device and polishing method

Abstract

The present invention belongs to the field of wafer polishing equipment, and specifically relates to a wafer edge polishing device and a polishing method. It includes a wafer fixing flip assembly, which includes a propulsion linear module and a machine base. A driven support seat is arranged beside the machine base. A swingable support arm is also arranged on the driven support seat. The support arm and the swing arm are arranged on both sides of the wafer rotating assembly to support the wafer rotating assembly. The wafer is arranged on the wafer rotating assembly. The polishing head driving assembly includes a base, a linear bearing mounting plate is arranged on the base, and a plurality of linear bearings are arranged on the linear bearing mounting plate. A guide shaft is arranged in each linear bearing. The upper end of the guide shaft is fixed to the upper connecting plate, and the lower end is fixed to the lower mounting plate. The polishing head assembly is arranged below the lower mounting plate through a shaft. The present invention prevents the polishing liquid from splashing everywhere, and greatly reduces the loss of the polishing liquid. The most important thing is that there will be no polishing liquid left on the surface of the wafer, which solves the problem of adsorption marks on the surface of the wafer.

Description

Technical Field

[0001] The invention belongs to the field of wafer polishing equipment, and in particular relates to a wafer edge polishing device and a polishing method. Background Art

[0002] Semiconductor silicon wafers are the main substrate materials for manufacturing ultra-large-scale integrated circuits. With the rapid development of the semiconductor industry, the precision requirements for substrate materials are becoming higher and higher, especially the edge surface state of silicon polished wafers is becoming more and more stringent. For silicon polished wafers with a diameter of more than 6 inches, especially 8 inches and 12 inches, it is generally necessary to polish the edge surface of the wafer during substrate processing to ensure that no slip lines or epitaxial stacking faults are generated at the edge of the wafer during epitaxy, thereby improving the yield of epitaxial wafers or devices. The edge polishing of the wafer is generally completed on an independent device, using a chemical polishing method, using a polishing liquid and a polishing cloth, and realizing the chemical mechanical polishing process under certain temperature and speed process conditions. Polishing the wafer reference surface is a step in the entire wafer edge polishing process. The wafer reference surface is usually also called a flat edge reference surface. This reference surface is straight. When performing edge polishing, the polishing degree of each part of the reference surface must be consistent, and the surface roughness after polishing must be the same. The edge surface of the wafer is polished evenly so that the upper part, the middle part and the lower part of the edge surface have the same polishing degree, so as to ensure that the polishing removal amount of each point on this reference surface is the same and has the same micro-roughness. If a part of the edge surface is not polished enough and the damaged layer is not completely removed, it will be easy to form the problem of multi-grain aggregation in the subsequent epitaxial process.

[0003] There are two main traditional polishing methods: one is to place the wafer on a rotating chuck, and polishing cloths are set around the upper surface, end surface, and lower surface of the wafer. When the wafer rotates at high speed, there is relative friction between the edge of the wafer and the polishing cloths around it, thereby polishing the edge surface of the wafer; the other is to fix the wafer on the chuck, and the polishing head rotates at high speed, and there is relative friction between the polishing cloth and the edge of the wafer, thereby polishing the edge of the wafer. However, no matter which method is used, polishing liquid needs to be sprayed on the polishing part of the wafer, and the polishing liquid splashes everywhere, causing suction cup marks on the lower surface of the wafer and the vacuum chuck, affecting the surface quality of the wafer.

[0004] In addition, the existing wafer edge polishing method is to polish the wafer edge surface through the relative friction generated by the forward rotation of the wafer and the reverse rotation of the polishing head assembly. This requires a higher concentricity between the wafer rotation and the polishing head rotation, otherwise it is easy to cause fragmentation. Summary of the invention

[0005] The technical problem to be solved by the present invention is to overcome the deficiencies in the prior art and provide a wafer edge polishing device and a polishing method.

[0006] In order to solve the above technical problems, the solution adopted by the present invention is:

[0007] Provided is a wafer edge polishing device, comprising a wafer fixing and flipping assembly, a wafer rotating assembly and a polishing head driving assembly;

[0008] The wafer fixing and flipping assembly comprises a pushing linear module and a machine base, the pushing linear module is mounted on the pushing linear module mounting plate, and the tightening cylinder mounting block is fixed on the slider of the pushing linear module; the tightening cylinder is fixed on the tightening cylinder mounting block, the cylinder piston rod is connected to the tightening block, the tightening block is mounted on the supporting seat connecting block, and the supporting seat and the swing motor mounting seat are fixedly mounted on the supporting seat connecting block; the swing motor mounting seat is mounted on the swing motor mounting seat, and the driving pulley is mounted on the swing motor; a horizontal linear guide rail is provided on the side of the machine base, the supporting seat is connected to the slider of the linear guide rail, a horizontal swing shaft is provided on the top of the machine base, the driven pulley is mounted on one end of the swing shaft, and the synchronous pulley connects the driving pulley and the driven pulley; the swing arm is fixedly mounted on the other end of the swing shaft, the driven support seat is arranged on the side of the machine base, and the driven support seat is also provided with a swingable support arm, the support arm and the swing arm are respectively arranged on both sides of the wafer rotating assembly for supporting the wafer rotating assembly; the wafer is arranged on the wafer rotating assembly;

[0009] The polishing head driving assembly includes a base, which is fixed on the frame, and a linear bearing mounting plate is mounted on the base. A plurality of linear bearings are arranged on the linear bearing mounting plate, and a guide shaft is arranged in each linear bearing. The upper end of the guide shaft is fixed to the upper connecting plate, and the lower end is fixed to the lower mounting plate; the upper mounting plate is connected to the slider of the lifting linear module, and the lower mounting plate can make linear motion up and down under the drive of the lifting linear module; a polishing head driving motor mounting seat is mounted on the lower mounting plate, and a polishing head driving motor is mounted on the polishing head driving motor mounting seat, and a driving gear is fixed on the output shaft of the motor, and the polishing head assembly is arranged below the lower mounting plate through a shaft, and a driven gear is arranged at the top of the shaft, and the driven gear is meshed with the driving gear; the polishing head assembly includes a polishing cloth, and a nozzle mounting block is also arranged below the lower mounting plate, and a fan-shaped nozzle is arranged on the nozzle mounting block for uniformly spraying polishing liquid onto the polishing cloth.

[0010] As an improvement, the chip rotation assembly includes a rotating motor mounting seat, the rotating motor is mounted on the rotating motor mounting seat, the rotating shaft is mounted on the rotating motor, a vacuum suction cup is mounted on the upper end of the rotating shaft, and a vacuum rotating joint is mounted on the lower end; two positioning cylinders are symmetrically and horizontally installed on both sides of the rotating motor mounting seat, one end of the guide rod is connected to the cylinder piston rod, and the other end is connected to the positioning slider, and a positioning guide wheel is provided on the positioning slider.

[0011] As an improvement, the polishing head assembly also includes a rotary joint and a polishing head bearing. The polishing head bearing is installed on the lower mounting plate through a polishing head bearing seat. The inner ring of the polishing head bearing is installed with a hollow polishing head shaft. The driven gear is installed on the upper part of the polishing head shaft. The upper end of the polishing head shaft is installed with a rotary joint; the polishing cloth mounting block is installed at the lower end of the polishing head shaft, and the polishing cloth is arranged on the polishing cloth mounting block; the polishing liquid conduit is arranged in the polishing head shaft, the top end is connected to the rotary joint, and the bottom end is connected to the polishing cloth mounting block. A liquid passage is provided in the polishing cloth mounting block and is connected to the polishing liquid conduit.

[0012] As an improvement, a tightening nut is provided on the cylinder piston rod for squeezing the tightening block.

[0013] As an improvement, the linear bearing mounting plate is rectangular, and four linear bearings are disposed at four corners of the linear bearing mounting plate.

[0014] The invention also provides a method for polishing the edge of a wafer using the wafer edge polishing device.

[0015] Compared with the prior art, the technical effects of the present invention are:

[0016] The present invention proposes a wafer edge surface polishing device which uses an immersion method to allow the polishing cloth to always absorb polishing liquid and keep it in a wet state. There is no need to spray the polishing liquid during the polishing process, which prevents the polishing liquid from splashing everywhere and greatly reduces the loss of the polishing liquid. The most important thing is that no polishing liquid will remain on the wafer surface, which solves the problem of adsorption marks on the wafer surface.

[0017] The wafer rotating assembly of the present invention is designed with a wafer positioning structure. When the wafer is placed on the suction cup, the wafer is accurately aligned and positioned by the positioning structure, thereby ensuring the concentricity of the wafer and the rotating motor and greatly reducing the fragmentation rate during the wafer edge polishing process.

[0018] The invention has a compact structure, is simple and practical, and the wafer contacts the polishing cloth at different angles under the drive of the swing motor to polish the upper and lower surfaces of the wafer edge. The swing angle is adjustable according to different process requirements, and can cope with wafers of different specifications. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is an isometric view of the present invention;

[0020] Figure 2 This is a schematic diagram of the structure of the wafer fixing and flipping assembly of the present invention;

[0021] Figure 3 A top view of a wafer fixing and flipping assembly of the present invention;

[0022] Figure 4 It is a schematic diagram of the structure of the wafer rotating assembly of the present invention;

[0023] Figure 5 A side view of a wafer rotating assembly of the present invention;

[0024] Figure 6 A top view of a wafer rotating assembly in the present invention;

[0025] Figure 7 A cross-sectional view of a wafer rotating assembly in the present invention;

[0026] Figure 8 It is a cross-sectional view of the blasting head assembly of the present invention.

[0027] Figure numerals: 1-wafer fixing flip assembly, 2-polishing head driving assembly, 3-wafer, 4-propelling linear module mounting plate, 5-propelling linear module, 6-tightening cylinder mounting block, 7-tightening cylinder, 8-tightening nut, 9-tightening block, 10-support seat connecting block, 11-swing motor mounting plate, 12-driving pulley, 13-swing motor, 14-synchronous belt, 15-linear guide rail, 16-support seat, 17-driven pulley, 18-swing shaft, 19-swing arm, 20-driven support seat, 21-wafer rotating assembly, 22-base, 23-linear bearing mounting plate, 24-linear bearing, 25-guide shaft, 26-upper connecting plate, 27-lifting linear module, 28-lower mounting plate, 29-polishing head assembly, 30-lifting connecting block, 31-polishing head drive motor, 32-polishing head drive motor mounting seat, 33-driving gear, 34-nozzle mounting block, 35-fan-shaped nozzle, 36-rotating motor mounting seat, 37-rotating motor, 38-rotating shaft, 39-vacuum rotary joint, 40-positioning slider, 41-positioning guide rod, 42-positioning cylinder connecting block, 43-vacuum suction cup, 44-positioning cylinder, 45-positioning guide wheel, 46-positioning guide wheel adjusting bolt, 47-rotating joint, 48-polishing liquid conduit, 49-gear locking nut, 50-driven gear, 51-polishing head bearing seat, 52-polishing head bearing, 53-polishing head rotating shaft, 54-polishing cloth mounting block, 55-polishing cloth, 56-polishing liquid, 57-polishing head locking nut. DETAILED DESCRIPTION

[0028] The specific implementation of the present invention is described in detail below in conjunction with the accompanying drawings.

[0029] like Figure 1 As shown, a wafer edge polishing device includes a wafer fixing and flipping assembly 1, a wafer rotating assembly 21 and a polishing head driving assembly 2.

[0030] like Figure 2As shown, the wafer fixing flip assembly 1 includes a push linear module mounting plate 4 and a machine base, the push linear module 5 is mounted on the push linear module mounting plate 4, the tightening cylinder mounting block 6 is fixed on the slider of the push linear module 5, and performs back and forth linear motion under the drive of the push linear module 5. The tightening cylinder 7 is fixed on the tightening cylinder mounting block 6, and a tightening nut 8 is connected to the cylinder piston rod to squeeze the tightening block 9. The tightening block 9 is mounted on the support seat 10, and a support seat 16 and a swing motor mounting seat 11 are fixedly mounted on the support seat connecting block 10. A horizontal linear guide is provided on the side of the machine base, and the support seat 16 is connected to the slider of the linear guide 15. When the tightening nut 8 presses the tightening block 9, all components connected to the support seat 16 can perform linear motion. A swing motor 13 is installed on the swing motor mounting base 11, a driving pulley 12 is installed on the swing motor 13, a swing shaft 18 is provided inside the top of the base, a driven pulley 17 is installed on one end of the swing shaft 18, a swing arm 19 is fixed on the other end of the swing shaft 18, a wafer rotating assembly 21 is installed on the swing arm 19, a driven support base 20 is provided on the side of the base, a swingable support arm is provided on the driven support base 20, and both ends of the wafer rotating assembly are connected to the swing arm 19 and the support arm.

[0031] like Figure 3 As shown, the polishing head driving assembly 2 includes a base 22 and a frame, the base 22 is fixed on the frame, the rectangular linear bearing mounting plate 23 is mounted on the base, four linear bearings 24 are mounted at the four corners of the linear bearing mounting plate 23, and the linear bearing 24 is provided with four guide shafts 25, the upper end of the guide shaft 25 is fixed to the upper connecting plate 26, and the lower end is fixed to the lower mounting plate 28. The upper mounting plate 26 is connected to the slider of the lifting linear module 27 through the lifting connecting block 30, and under the drive of the lifting linear module 27, the lower mounting plate 28 can move linearly up and down. A polishing head driving motor mounting seat 32 is installed on the lower mounting plate 28, and two polishing head assemblies and a nozzle mounting block 34 are arranged below the lower mounting plate 28. The polishing head assembly includes a polishing cloth 55, and a polishing head driving motor 31 is installed on the polishing head driving motor mounting seat 23. A driving gear 33 is fixed on the output shaft of the motor, and is meshed with a driven gear 50 on the polishing head assembly 29. Under the drive of the polishing head driving motor 31, the polishing head can rotate. In addition, the fan-shaped nozzle 35 is installed on the nozzle mounting block 34, and the polishing liquid 56 and pure water sprayed from the fan-shaped nozzle 35 can be sprayed onto the polishing cloth 55 in a fan-shaped manner to ensure that the polishing cloth 55 is completely soaked in the polishing liquid.

[0032] like Figure 4As shown, the wafer rotating assembly 21 includes a rotating motor mounting seat 36, a rotating motor 37 is mounted on the rotating motor mounting seat 36, a rotating shaft 38 is mounted on the rotating motor 37, a vacuum suction cup 43 is mounted on the upper end of the rotating shaft 38, and a vacuum rotating joint 39 is mounted on the lower end, which can be connected to a vacuum air pipe. When the wafer 3 is placed on the vacuum suction cup 43, it is fixed on the vacuum suction cup 43 under the adsorption of the vacuum force, and the wafer 3 can achieve rotational movement under the drive of the rotating motor 37. In addition, positioning cylinders 44 are symmetrically installed on both sides of the rotating motor mounting seat 36, and the piston rod of the positioning cylinder 44 is connected to the positioning cylinder connecting block 42. One end of the two positioning guide rods 41 is fixed on the positioning cylinder connecting block 42, and the other end is fixed on the positioning slide block 40. With the extension and retraction of the piston rod of the positioning cylinder 44, the positioning slide blocks 40 on both sides can achieve opening and closing movements. Two positioning guide wheels 45 are installed on the positioning sliders 40 on both sides. When the piston rods of the positioning cylinders 44 on both sides are extended, the chip 3 can be clamped to position the chip 3. The chip 3 and the rotating shaft 38 maintain theoretically consistent concentricity. In order to improve the concentricity between the chip 3 and the rotating shaft 38, each positioning guide wheel 45 is designed with a positioning guide wheel adjusting bolt 46 to adjust the position accuracy of the positioning guide wheel 45.

[0033] like Figure 5 As shown, the polishing head assembly 29 includes a rotary joint 47, a polishing liquid conduit 48 and a polishing cloth 55. The polishing head bearing seat 51 is mounted on the lower mounting plate 28, a polishing head bearing 52 is mounted in the polishing head bearing seat 51, a hollow polishing head shaft 53 is mounted on the inner ring of the polishing head bearing 51, a polishing liquid conduit 48 is provided in the polishing head shaft 53, a driven gear 50 is mounted on the polishing head shaft 53 through a gear locking nut 49, a rotary joint 47 is mounted on the upper end of the polishing head shaft 53, and a polishing cloth mounting block 54 is mounted on the lower end of the polishing head shaft 53 through a polishing head locking nut 57. A liquid passage is provided in the polishing cloth mounting block 54, and the polishing liquid conduit 48 is connected with the rotary joint 47 and the liquid passage in the polishing cloth mounting block 54. The polishing liquid 56 is introduced from the rotary joint 47, enters the polishing cloth mounting block 54 through the polishing liquid conduit 48, and directly contacts the back of the polishing cloth 55.

[0034] The principle of the present invention is that the upper, middle and lower surfaces of the edge of the wafer 3 are in contact with the polishing cloth 55 respectively. During the polishing process, the polishing cloth can not only rotate around the central axis, but also move up and down. The wafer 3 can not only rotate around the central axis, but also fit with the polishing cloth 55 at different angles. The mutual friction between the wafer 3 and the polishing cloth 55 polishes the upper surface, end surface and lower surface of the edge of the wafer 3. Before polishing the wafer 3, the fan-shaped nozzle 35 first sprays the polishing liquid 56 evenly on the polishing cloth 55, so that the polishing cloth 55 completely absorbs the polishing liquid 56. During the rotation of the polishing head, the polishing liquid is directly contacted with the polishing cloth 55 by the action of centrifugal force, so that the polishing cloth 55 is always in a state of absorbing the polishing liquid 56, and the wafer 3 can be directly polished.

[0035] The method for polishing the edge surface of a wafer using the above device comprises the following steps:

[0036] (1) First, the wafer 3 is placed on the vacuum suction cup 43 by a robot. At this time, the piston rods in the positioning cylinders 44 on both sides of the wafer rotation assembly 21 are extended, and the positioning slide blocks 40 on both sides are closed under the drive of the positioning cylinders 44. The four positioning guide wheels 45 are tangent to the edge of the wafer 3, that is, the position of the wafer 3 is accurately located, ensuring the concentricity of the wafer 3 and the rotating motor 37.

[0037] (2) The fan-shaped nozzle 35 sprays the polishing liquid 56 onto the polishing cloth 55 , and at the same time, the polishing cloth 55 rotates at a certain speed so that the polishing liquid 56 is evenly sprayed onto the surface of the polishing cloth 55 .

[0038] (3) After the position of the wafer 3 is determined, the vacuum force generated by the vacuum suction cup 43 fixes the wafer 3. Driven by the linear push module 5, the edge of the wafer 3 is pressed against the polishing cloth 55. At the same time, the piston rod of the pressing cylinder 7 is extended, so that the wafer 3 is pressed against the surface of the polishing cloth 55 with a certain pressure.

[0039] (4) The polishing head assembly 29 rotates at a certain speed under the drive of the polishing head driving motor 31, and the wafer 3 rotates at a certain speed in the direction opposite to the polishing head under the drive of the rotating motor 37; the wafer 3 and the polishing cloth 55 rub against each other to polish the edge surface of the wafer 3.

[0040] (5) First, the wafer 3 is in a horizontal state driven by the swing motor 13, and the end face of the edge of the wafer 3 is polished first; after completion, the swing motor 13 rotates an angle so that the upper surface of the edge of the wafer 3 fits with the polishing cloth 55, and the upper surface is polished at this time; after completion, the swing motor 13 rotates an angle again so that the lower surface of the edge of the wafer 3 fits with the polishing cloth 55, and the lower surface is polished.

[0041] (6) During the polishing process of the edge surface of the wafer 3, the polishing cloth 55 is driven by the lifting linear module 27 to reciprocate up and down at a certain speed, thereby ensuring that the polishing cloth 55 can evenly polish the edge of the wafer 3 and improving the service life of the polishing cloth 55.

[0042] (7) After the edge surface polishing of the wafer 3 is completed, each moving component stops, and the wafer 3 returns to the initial position under the drive of the propulsion linear module, and the robot can move the wafer 3 to the next station.

[0043] Finally, it should be noted that the above examples are only specific embodiments of the present invention. Obviously, the present invention is not limited to the above examples, and there are many variations. All variations that can be directly derived or associated with the content disclosed by a person skilled in the art should be considered as the protection scope of the present invention.

Claims

1. A wafer edge polishing device, characterized in that: It includes a wafer fixing and flipping assembly, a wafer rotating assembly and a polishing head driving assembly; The wafer fixing flipping assembly comprises a pushing linear module and a machine base, the pushing linear module is installed on the pushing linear module mounting plate, and the tightening cylinder mounting block is fixed on the slider of the pushing linear module; the tightening cylinder is fixed on the tightening cylinder mounting block, the cylinder piston rod is connected to the tightening block, the tightening block is installed on the supporting seat connecting block, and the supporting seat and the swing motor mounting seat are fixedly installed on the supporting seat connecting block; the swing motor mounting seat is installed on the swing motor mounting seat, and the driving pulley is installed on the swing motor; a horizontal linear guide rail is provided on the side of the machine base, the support seat is connected to the slider of the linear guide rail, a horizontal swing shaft is provided on the top of the machine base, the driven pulley is installed at one end of the swing shaft, and the synchronous pulley connects the driving pulley and the driven pulley; the swing arm is installed and fixed on the other end of the swing shaft, the driven support seat is arranged on the side of the machine base, and the driven support seat is also provided with a swingable support arm, the support arm and the swing arm are respectively arranged on both sides of the wafer rotating assembly for supporting the wafer rotating assembly; the wafer is arranged on the wafer rotating assembly; The polishing head driving assembly includes a base, which is fixed on the frame, and a linear bearing mounting plate is mounted on the base. A plurality of linear bearings are arranged on the linear bearing mounting plate, and a guide shaft is arranged in each linear bearing. The upper end of the guide shaft is fixed to the upper connecting plate, and the lower end is fixed to the lower mounting plate; the upper mounting plate is connected to the slider of the lifting linear module, and the lower mounting plate can make linear motion up and down under the drive of the lifting linear module; a polishing head driving motor mounting seat is installed on the lower mounting plate, and a polishing head driving motor is installed on the polishing head driving motor mounting seat, and a driving gear is fixed on the output shaft of the motor, and the polishing head assembly is arranged below the lower mounting plate through an axis, and a driven gear is arranged at the top of the axis, and the driven gear is meshed with the driving gear; the polishing head assembly includes a polishing cloth, and a nozzle mounting block is also provided below the lower mounting plate, and a fan-shaped nozzle is provided on the nozzle mounting block for spraying polishing liquid onto the polishing cloth; The wafer rotating assembly includes a rotating motor mounting seat, the rotating motor is mounted on the rotating motor mounting seat, the rotating shaft is mounted on the rotating motor, a vacuum suction cup is mounted on the upper end of the rotating shaft, and a vacuum rotating joint is mounted on the lower end; two positioning cylinders are symmetrically and horizontally mounted on both sides of the rotating motor mounting seat, one end of the guide rod is connected to the cylinder piston rod, and the other end is connected to the positioning slider, and a positioning guide wheel is provided on the positioning slider; The polishing head assembly also includes a rotary joint and a polishing head bearing. The polishing head bearing is installed on the lower mounting plate through a polishing head bearing seat. A hollow polishing head shaft is installed on the inner ring of the polishing head bearing. The driven gear is installed on the upper part of the polishing head shaft. A rotary joint is installed on the upper end of the polishing head shaft. The polishing cloth mounting block is installed at the lower end of the polishing head shaft, and the polishing cloth is arranged on the polishing cloth mounting block. The polishing liquid conduit is arranged in the polishing head shaft, the top end is connected to the rotary joint, and the bottom end is connected to the polishing cloth mounting block. A liquid passage is arranged in the polishing cloth mounting block and is connected to the polishing liquid conduit.

2. The device according to claim 1, characterized in that A tightening nut is arranged on the cylinder piston rod for squeezing the tightening block.

3. The device according to claim 1, characterized in that The linear bearing mounting plate is rectangular, and four linear bearings are arranged at four corners of the linear bearing mounting plate.

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