A process for controlling surface defects of gallium antimonide polished wafers

Abstract

A process method for controlling surface defects of a polished gallium antimonide wafer relates to wafer polishing technology. The invention first optimizes a crystal outer circle rolling process, controls the crystal outer circle rolling feed amount and the crystal movement rate, so as to obtain a surface with a dense crystal structure and good finish; designs a crystal chamfering process, and optimizes the grinding wheel grit, number of chamfering turns and feed speed of the chamfering under different conditions; designs the radius of the wafer main positioning fillet, changes the previous main edge sharp corner into a fillet, thereby ensuring that the main edge fillet can withstand external forces without problems such as falling off and slagging; designs a gallium antimonide wafer edge end face polishing technology, so as to obtain a dense and bright edge structure without chamfering tracks; finally, optimizes the three major processes of gallium antimonide wafer polishing. Through systematic process control, the structure of the wafer edge is stabilized, and wafer edge shedding is greatly reduced, so that the "dark scratch" of the wafer in the final polishing is reduced from 60% to 10%, and the final polishing pass rate is greatly improved.

Description

Technical Field

[0001] The invention belongs to the technical field of wafer polishing, and in particular relates to a process method for controlling surface defects of a gallium antimonide polished wafer. Background Art

[0002] Group III-V compound semiconductor materials have attracted widespread attention due to their advantages in optoelectronic device applications. Antimonide infrared optoelectronic devices, with their excellent performance, show great application prospects in infrared imaging, medical diagnosis, resource exploration, gas detection, optical communications, thermophotovoltaics, and other fields, and have become a current research hotspot. Gallium antimonide (GaSb), a typical Group III-V compound semiconductor material, has a band gap of 0.725 eV and a lattice constant of 6.0959 Å. It is lattice-matched with Group III-V materials with a lattice constant of 6.1 Å and their ternary and quaternary antimony-containing compounds. Its wavelength range covers the near-infrared to far-infrared band, making it an ideal substrate material for the preparation of antimonide infrared optoelectronic devices. GaSb single crystals have a direct impact on the performance of antimonide infrared optoelectronic devices. Improving device performance requires single crystals with large size, lower defect density, and better surface quality. In recent years, antimonide infrared photoelectric technology has developed rapidly, especially the development and application of antimonide type II superlattice infrared focal plane detection technology, which has greatly promoted the development of GaSb materials. More and more institutions and enterprises have also invested in the research and development and production of GaSb single crystals.

[0003] The production of gallium antimonide single crystal wafers primarily relies on achieving high-quality surface preparation through processes such as polishing and cleaning. GaSb is a highly chemically active material that is easily oxidized, requiring a high level of surface preparation, making it more challenging to process than materials such as GaAs and InP. With the advancement of device epitaxial growth processes, the requirements for single crystal surface performance are becoming increasingly stringent, making high-quality surface preparation a key component of GaSb single crystal development. To meet the demands of epitaxial material growth, single crystal surfaces must exhibit low roughness, minimal residual impurities and defects, and a low surface oxide layer thickness.

[0004] The traditional method for polishing gallium antimonide wafers is chemical mechanical polishing. The CMP mechanism involves material removal from the wafer surface through a combination of chemical oxidation and mechanical grinding. During the CMP process, chemical oxidation creates a soft layer with lower hardness on the wafer surface, which is then removed by mechanical grinding. CMP typically utilizes nano-silicon oxide or aluminum oxide polishing slurries and various polishing machines.

[0005] Currently, the main surface defects of large-diameter GaSb chemical mechanical polishing wafers are dark scratches and particles. Dark scratches are relatively small, about a few microns, and can usually be seen under strong light by changing different angles. They can also be observed under a 200x microscope. Dark scratches directly affect the subsequent epitaxy and the yield rate of detector devices.

[0006] Rough and intermediate polishing of GaSb wafers, influenced by the polishing cloth and polishing chemicals, can easily produce macroscopically visible scratches and marks. These scratches are distributed in a cross-sectional, linear, and curved pattern, and can be as large as 10 microns. Final fine polishing can remove these scratches and marks from the intermediate polishing process. However, during fine polishing, a macroscopically invisible "dark scratch" defect, several microns in size and varying in length, has been discovered. These scratches appear and disappear intermittently, varying in location and length, directly impacting the first-pass yield of GaSb wafers.

[0007] We analyzed the location and length of "dark scratches" on numerous wafer surfaces after fine polishing and found that the location and length of the scratches varied. We observed the edge morphology before chamfering and after fine polishing under a microscope at 50-200x magnification and found that the edge morphology continued to change. After fine polishing, the wafer edge had numerous small micron- and nanometer-scale notches, resulting in an uneven end face. Using a process of elimination to eliminate factors such as polishing chemicals, liquid, cloth, and particles, we ultimately focused on the connection between the "dark scratch" defect on the wafer surface and the detached material from the wafer edge. Summary of the Invention

[0008] To mitigate the generation of debris from wafer edges and the impact of this debris on the wafer surface, the present invention provides a process for controlling surface defects in polished gallium antimonide wafers. This process advances the manufacturing process through two process innovations and multiple process optimizations, resulting in a new process for controlling surface defects in gallium antimonide wafers that significantly reduces and mitigates dark scratches.

[0009] The technical solution provided by the present invention is: a process for controlling surface defects of a gallium antimonide polished wafer, comprising the following steps:

[0010] S1, crystal rolling outer circle;

[0011] S2. Wafer chamfering: According to the thickness of the wafer, design the angle of the grinding wheel R angle and determine the depth of the A1 and A2 surface widths; increase the left and right fillet radius of the main and auxiliary positioning edges by more than 3 times on the current basis, so that the fillet radius of the main and auxiliary positioning edges is changed from sharp corners to rounded corners, which improves the wafer's ability to withstand external force impact during polishing and reduces the risk of edge knocking, edge drop and slag drop at the left and right corners of the wafer's main positioning edges; for rough chamfering, use a grinding wheel with a mesh number ≥1800 for rough chamfering, control the grinding wheel feed rate at 0.2-0.4mm / min, and the number of chamfering circles is ≥2 circles; for fine chamfering, use a grinding wheel with a mesh number ≥6000 for fine chamfering, control the grinding wheel feed rate at 0.2-0.4mm / min, and the number of chamfering circles is ≥2 circles; after fine chamfering, first check under fluorescent light, the wafer edge is uniform, there is no chipping or notch, which is qualified; then check under a 20x profilometer microscope, and the error between the A1, A2 surface width and R angle accuracy and the design value is within a reasonable range, which is qualified;

[0012] S3, chemical etching of chip chamfers;

[0013] S4. Mechanical polishing of wafer chamfers: Using a domestically produced 6B single-sided polishing machine, use a polishing slurry with a particle size of ≤100nm. Add an oxidizing agent to the polishing slurry to create a polishing slurry with a pH of ≥8. Place a black damping polishing cloth with a hardness of ≤40 on the polishing machine turntable. Manually fix the wafer in an upright position and polish the upright wafer on the polishing cloth. The main disk speed of the polishing machine is ≤5r / min, and the polishing slurry flow rate is 100-200ml / min. Perform chemical mechanical polishing on the chamfer of the gallium antimonide wafer by manually rotating the wafer for 60-120s. Rinse with high-purity water after polishing and spin dry. Observe with the naked eye under fluorescent light; wafer edges that are delicate, uniform, and shiny are considered acceptable.

[0014] S5. Wafer polishing: including rough polishing, medium polishing and fine polishing;

[0015] S6, wafer cleaning;

[0016] S7, drying the wafer;

[0017] S8, wafer inspection;

[0018] S9. Chip storage.

[0019] A further technical solution is: in S1, select a grinding wheel with a mesh size of ≥800, a grinding wheel feed amount of ≤0.5 mm / min, and a crystal moving rate of ≤3 mm / min.

[0020] A further technical solution is: use inorganic acid solution, buffer and high-purity water with a resistivity of 18 megohms to prepare a solution with a pH value of 5-6, chemically corrode the edge of the chamfered chip at 18-24°C for 20-30s, then rinse with high-purity water and dry; observe with the naked eye under a fluorescent light, and the chip edge is qualified if there is no obvious adsorbent, particles or burrs.

[0021] Further technical solutions are:

[0022] In S5, rough polishing is performed; the hardness of the polishing cloth selected is ≤80, the particle size of the polishing liquid selected is ≤150nm and the pH value is 7-12, and the polishing liquid is added with an oxidant to prepare a polishing liquid with a pH value of 8-12. The wafer is fixed on a wax-free pad and the polishing pressure is ≤200g / cm 2 , main disk speed 40-80r / min, polishing liquid flow ≤400ml / min, double-sided polishing, polishing removal amount controlled at 30-40 microns; after rough polishing, observe under fluorescent light and enter medium polishing after no obvious scratches, saw marks, etc.;

[0023] Medium polishing: The hardness of the polishing cloth should be ≤60, the particle size of the polishing liquid should be ≤100nm and the pH value should be ≥8. After adding an oxidant to the polishing liquid, the pH value should be 9-10. The wafer should be fixed on a wax-free pad and the polishing pressure should be ≤150g / cm 2 , main disk speed 40-60r / min, polishing liquid flow 300-400ml / min, double-sided polishing, polishing removal ≤ 20 microns; after medium polishing, observe under a strong light and enter fine polishing after no obvious scratches, saw marks, etc.;

[0024] Fine polishing: The hardness of the polishing cloth should be ≤40, the compression elasticity should be 50-90%, and the opening diameter should be ≥200 mesh. The polishing liquid should be mainly oxidant, with a pH value of 4-8. The wafer should be fixed on a wax-free pad, and the polishing pressure should be ≤100g / cm 2 The main disk speed is 40-60r / min, the polishing liquid flow rate is 300-400ml / min, and both sides are polished. The polishing removal amount is ≤10 microns. After fine polishing, observe under a strong light to see if there are obvious scratches, bright scratches, dark scratches, NG, and chemicals before cleaning.

[0025] A further technical solution is: in S6, after the wafer is polished, the lower plate is quickly flushed with water, the water gun pressure on both sides of the main plate is ≥1.5kg, and the megasonic wave-assisted high-purity water gun flushes the surface in different directions for ≤30S. The water flow direction is consistent, and there must be no backflow of flushing water.

[0026] A further technical solution is to check the wafer surface from different angles for defects such as dark scratches, dirty spots, dark spots, potions, and dirty potions under a 40W strong light and a 20x microscope.

[0027] The further technical solution is: the wafer storage room is a Class 100 environment, the room temperature is controlled at 18-22℃, and the humidity is controlled at ≤60%.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] 1. First, the crystal outer circle rolling process was optimized to obtain a relatively delicate and dense crystal surface. The grinding wheel mesh number selected in the process is ≥800 mesh. The grinding wheel feed rate is about 10 times slower than the previous crystal outer circle rolling speed, and the crystal movement rate is 5-8 times slower than before. The obtained crystal surface has no knife marks and no grinding wheel grinding tracks, and is relatively delicate. The stress of the crystal is also effectively released.

[0030] 2. The process of chamfering the edge of gallium antimonide wafers was optimized and designed to obtain a better chamfered end face. First, the grinding wheel structure and mesh size for chamfering soft gallium antimonide wafers were formulated, and the feed speed and moving speed were adjusted in the process to ensure the smoothness of the wafer edge.

[0031] 3. In the past, the left and right corner radii of the main positioning edge of the wafer were mostly sharp corners, which were easily knocked and chipped when impacted by external forces. The present invention innovatively designs the size of the left and right corner radii of the main positioning edge, and obtains larger left and right corner radii, which improves the ability of the wafer to withstand external force impact during polishing and reduces the risks of knocking, chipping and chipping of the left and right corners of the main positioning edge of the wafer.

[0032] 4. The present invention performs chemical etching of inorganic acid or ammonia series on the edge chamfered GaSb wafer to ensure that the wafer edge structure is dense and has no loose layer, and to ensure that the edge does not slag or fall off, thereby reducing the generation of dark scratches on the fine polishing surface.

[0033] 5. The present invention is designed to perform chemical mechanical polishing on the edge of the chip to obtain a high-end surface with a shallow damage layer and high smoothness, so as to prevent the chip edge from being affected by external forces and causing slag to fall off, resulting in dark scratches. At the same time, it can control the various substances that are easily retained due to the rough edge and are easy to diffuse back to the positive surface during epitaxy.

[0034] 6. The present invention optimizes the wafer polishing process, selects appropriate polishing pressure, filters the polishing liquid multiple times, balances chemical removal and mechanical removal forces, and adjusts the flow rate and rotation speed of the polishing liquid to effectively control the chip edge shedding and the problem of "dark scratches" easily generated on the wafer surface, thereby effectively improving the wafer one-time pass rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 The crystal of the present invention is rolled outward and the surface is chemically etched.

[0036] Figure 2 This is the chamfered edge of the wafer before the optimization process of the present invention.

[0037] Figure 3 This is the chamfered edge of the wafer after the optimization process of the present invention.

[0038] Figure 4 These are the left and right sharp corners of the main positioning edge before the optimization process of the present invention.

[0039] Figure 5 These are the left and right sharp corners of the main positioning edge after the optimization process of the present invention.

[0040] Figure 6 This is the length of the 10*10 "dark scratch" of the microscope before the optimization process of the present invention.

[0041] Figure 7 This is the width of the 10*10 "dark scratch" of the microscope before the optimization process of the present invention.

[0042] Figure 8 After the optimization process of the present invention, the microscope is 10*10 and there is no "dark scratch" on the chip surface. DETAILED DESCRIPTION

[0043] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0044] This embodiment discloses a process for controlling surface defects of a gallium antimonide polished wafer, comprising the following steps:

[0045] 1. Optimized the crystal outer circle rolling process.

[0046] Gallium antimonide has a hardness of 1.5, making it softer than gallium arsenide and indium phosphide. Therefore, we first optimized the crystal rolling process. We selected a grinding wheel with a grit of 800 or higher, with a grinding wheel feed rate approximately 10 times slower than previous crystal rolling processes, and a crystal movement rate 5-8 times slower. The resulting crystal surface is free of knife marks and grinding wheel tracks, resulting in a fine, dense structure and effective stress relief.

[0047] 2. Optimized the chip chamfering process.

[0048] Typically, semiconductor silicon, gallium arsenide, and indium phosphide wafers have R-shaped or T-shaped chamfers, with most using an R-shaped chamfer. The R-shaped radius is determined by the final thickness of the wafer. Based on the wafer thickness, the grinding wheel R angle is designed to determine the A1 and A2 surface depths. We use an R-shaped chamfer.

[0049] The wafer chamfering process is divided into coarse chamfering and fine chamfering, and the grinding wheels used are of different grits. I optimized the process and used a grinding wheel with a grit of 1800 or higher for coarse chamfering. During the chamfering process, the feed rate was controlled at 0.2-0.4mm / min, and the number of chamfering turns was 2 or higher. Fine chamfering was performed using a grinding wheel with a grit of 6000 or higher, with the feed rate controlled at 0.2-0.4mm / min, and the number of chamfering turns was 2 or higher. After fine chamfering, the wafer edge was inspected under a fluorescent light to ensure there were no chipping or notching, and the edge was relatively uniform with good finish and roughness. The wafer was then tested under a 20x profilometer microscope. The R angle accuracy was considered acceptable if the error between the design value and the R angle accuracy was within a reasonable range. Because we optimized the process, the coarse chamfering grinding wheel was changed from 800 mesh to ≥1800 mesh, and the fine grinding wheel was changed from 4000 mesh to ≥6000 mesh. The chamfering process slowed down the feed rate and increased the number of chamfering circles, resulting in an end face with small edge roughness, better structure, and less prone to falling debris.

[0050] 3. The radius of the left and right corners of the main and auxiliary positioning edges are innovatively designed.

[0051] At present, the left and right fillet radii of the main positioning edges of the chip are set to ≤3mm, and most of their shapes are sharp corners. Considering that when the main and secondary positioning edges are sharp corners, the external impact force they can withstand is relatively small, and the edges are prone to falling off. We designed the left and right fillet radii of the main and secondary positioning edges of the chip to be enlarged by more than 3 times, and the corners have changed from the previous "sharp corners" to "rounded corners", greatly reducing problems such as edge knocking, edge falling and slag falling.

[0052] 4. Optimized chemical etching to remove the loose layer on the edge of the wafer.

[0053] Usually, chemical etching is performed after the chip is chamfered to remove the edge damage layer and loose layer. We have optimized a new process method to use stable acidic and alkaline solutions with relatively slow chemical reaction rates for etching, which can obtain a chip with low edge roughness and a relatively smooth surface.

[0054] Specifically, we use a 10% or higher inorganic acid solution and buffer, along with 18 megohm high-purity water to create a chemical etching solution. The pH of the chemical etching solution is 5-6. At 18-24°C, the chamfered wafer edge is chemically etched for approximately 20-30 seconds. The wafer is then rinsed with high-purity water and dried. This removes residue, particulate matter, and metallic impurities from the wafer surface and edge. After drying, the wafer surface is visually observed under a fluorescent light. A shinier edge with no noticeable adsorbed matter, particles, or burrs is considered acceptable. The resulting wafer edge surface finish is smoother than before the etching.

[0055] 5. Optimized the chip end face polishing to improve the chip finish.

[0056] Wafer edge polishing can increase the density of the crystal structure and control the problem of residue and easy falling off on the edge of the wafer. At present, only large-diameter silicon is subjected to edge chemical mechanical polishing, while other materials have not yet started. We use chemical mechanical polishing to polish the edges of gallium antimonide wafers and obtain a polished end face with relatively good finish.

[0057] Specifically, we used a domestically produced 6B single-side polishing machine with a polishing slurry (colloidal silica solution, pH ≥ 9) with a particle size ≤ 100nm and an oxidizing agent (hydrogen peroxide, sodium dichloroisocyanurate, sodium bicarbonate, tartaric acid, organic acid, etc.) to create a polishing slurry with a pH ≥ 8. We used a domestically produced black damping cloth with a hardness ≤ 40. We manually positioned the wafer end face upright, with the polisher's main platen speed ≤ 5 rpm and a polishing slurry flow rate of 100-200 ml / min. We chemically mechanically polished the GaSb wafer end face for 60-120 seconds. The wafer was then rinsed with high-purity water and dried individually. The edge face was inspected under fluorescent light; a uniform, shiny, and smooth surface was considered acceptable. Further examination under a 20x microscope confirmed the end face was smooth, shiny, and free of chamfered edges. Chemical mechanical polishing of the wafer edge provides the basis for wafer polishing and preventing edge peeling. The edges of large-diameter silicon wafers have been fully polished, while the edges of gallium antimonide wafers have not yet been polished (the main reason is that gallium antimonide is soft and brittle, making it too difficult to polish, and the polishing method for silicon wafer edges is not suitable for gallium antimonide).

[0058] 6. Optimize the wafer polishing process.

[0059] We optimized the wafer polishing process and used three SEEDFAM-32G single-side polishers of the same model to perform coarse, medium, and fine chemical mechanical polishing on 2-inch (12 wafers / tray) and 3-inch (5 wafers / tray) GaSb wafers.

[0060] The polishing cloth used for rough polishing is a colorless white cloth with appropriate hardness, its hardness ≤80, the polishing abrasive liquid (silicon solution pH value 7-12, particle size ≤150nm) plus an oxidant (sodium dichloroisocyanurate, sodium phosphate, sodium pyrophosphate, organic acid...), its pH value is controlled between 8-12, the wafer is fixed on a wax-free pad, and the polishing pressure is ≤200g / cm 2 , main disk speed 40-80r / min, flow rate ≤400ml / min, double-sided polishing, polishing removal amount 30-40 microns, observe under fluorescent light without obvious scratches, saw marks, etc., then enter the middle polishing.

[0061] The polishing cloth used for polishing gallium antimonide wafers is a relatively suitable black damping cloth with a hardness of ≤60. The polishing liquid used is a silica colloidal solution with a particle size of ≤100nm and a pH value of ≥8, plus an oxidant (hydrogen peroxide, sodium dichloroisocyanurate, sodium phosphate, sodium pyrophosphate, organic acid, inorganic acid, etc.) to form the polishing liquid. Its pH value is controlled between 9-10. The wafer is fixed on a wax-free pad. The polishing liquid is supplied by a peristaltic pump, filtered in series by two ≤0.5 micron filter cartridges, and then distributed to the main plate through a latex tube at a rate of 300-400ml / min. The pressure on the upper polishing plate is ≤150g / cm 2 The main disk speed is 40-60r / min, the polishing removal amount is ≤20 microns, and after observing under a strong light and finding no obvious scratches or scratches, it enters the fine polishing.

[0062] The final fine polishing is performed using black damping cloth with a hardness of ≤40, a compression modulus of 50-90%, and an opening diameter of ≥200 mesh. The main components of the polishing liquid are oxidants (hydrogen peroxide, potassium hypochlorite, sodium dichloroisocyanurate, organic acid, inorganic acid, sodium hypochlorite, tartaric acid, etc.) and a pH value between 4 and 8. The wafer is fixed on a wax-free pad. The polishing liquid is supplied by a peristaltic pump, filtered in series by multiple ≤0.3 micron filter cartridges, and distributed to the main plate through a latex tube at a rate of 300-400 ml / min. The upper polishing plate pressure is ≤100 g / cm 2 The main disk speed is 40-60r / min, the polishing removal amount is ≤10 microns, and there are no obvious scratches, bright scratches, dark scratches, NG, chemicals, etc. when observed under a strong light.

[0063] After polishing, the plate is quickly removed and the wafer surface is rinsed with high-purity water with a pressure of ≥1.5KG using two guns with megasonic assistance, thus achieving a stable process.

[0064] 7. Chip cleaning.

[0065] After fine polishing, the lower plate of the wafer is quickly flushed with water. The water gun pressure on both sides of the main plate is ≥1.5KG. Megasonic wave-assisted high-purity water guns are used in different directions to fully cover the surface for ≤30S. The water flow direction is consistent and there must be no backflow of water.

[0066] 8. Wafer inspection.

[0067] Under a 40W strong light and a 20x microscope, check the wafer surface from different angles for defects such as dark scratches, dirty spots, dark spots, potions, and potion dirt.

[0068] 9. Chip storage.

[0069] The wafer storage room is a Class 100 environment, with room temperature controlled at 18-22°C and humidity controlled at ≤60%.

[0070] In summary, the present invention first optimizes the crystal outer circle rolling process, controls the crystal outer circle rolling feed amount and the crystal moving rate, so as to obtain a dense crystal structure and a smooth surface; designs a crystal chamfering process, optimizes the grinding wheel grit, chamfering circle number and feed speed of chamfering under different conditions; analyzes the influence of the radius of the main and secondary positioning edges of the chip on the main and secondary edge fillet morphology, designs the radius of the main positioning fillet of the chip, and changes the previous main edge sharp corner into a rounded corner, so as to ensure that the main edge fillet can withstand external force without falling off, slag falling and other problems; analyzes the large Polishing the edges of diameter silicon wafers can reduce the various particles and residues that are easily retained on the edges. This paper designs a gallium antimonide wafer edge end face polishing technology to obtain a dense, bright edge structure without chamfered edge tracks. Finally, the three major processes of gallium antimonide wafer polishing (rough polishing, medium polishing and fine polishing) are optimized. Different consumables are selected for different process sections, and different process parameters are set. Through systematic process control, the structure of the wafer edge is stable, and the wafer edge shedding is greatly reduced. The final polishing "dark scratch" of the wafer is reduced from 60% to 10%, and the final polishing pass rate is greatly improved.

Claims

1. A process for controlling surface defects of a gallium antimonide polished wafer, characterized in that The following steps are involved: S1, crystal rolling outer circle; S2. Wafer chamfering: According to the thickness of the wafer, design the angle of the grinding wheel R angle and determine the depth of the A1 and A2 surfaces; increase the left and right fillet radius of the main and auxiliary positioning edges by more than 3 times on the current basis, so that the left and right fillet radius of the main and auxiliary positioning edges change from sharp corners to rounded corners; for rough chamfering, use a grinding wheel with a mesh number ≥1800 for rough chamfering, control the grinding wheel feed rate at 0.2-0.4mm / min, and the number of chamfering circles ≥2 circles; Fine chamfering: Use a grinding wheel with a mesh size of ≥6000 for fine chamfering, control the grinding wheel feed rate at 0.2-0.4mm / min, and the number of chamfering turns ≥2 turns; after fine chamfering, first check under fluorescent light, and the wafer edge is uniform, without edge collapse or notch, which is qualified; then check under a 20x profilometer microscope, and the error between the A1, A2 surface width and R angle accuracy and the design value is within a reasonable range, which is qualified; S3, chemical etching of chip chamfers; S4. Mechanical polishing of wafer chamfers: Using a domestically produced 6B single-sided polishing machine, use a polishing slurry with a particle size ≤100nm. Add an oxidizing agent to the polishing slurry to create a polishing slurry with a pH ≥8. Place a black damping polishing cloth with a hardness ≤40 Shore A on the polishing machine turntable. Manually fix the wafer in an upright position and polish the upright wafer on the polishing cloth. The main disk speed of the polishing machine is ≤5r / min, and the polishing slurry flow rate is 100-200ml / min. Chemically mechanically polish the chamfer of the gallium antimonide wafer by manually rotating the wafer for 60-120s. Rinse with high-purity water after polishing and spin dry. Observe with the naked eye under fluorescent light; wafer edges that are delicate, uniform, and shiny are considered acceptable. S5. Wafer polishing: including rough polishing, medium polishing and fine polishing; S6, wafer cleaning; S7, drying the wafer; S8, wafer inspection; S9. Chip storage.

2. The method for controlling surface defects of a gallium antimonide polished wafer according to claim 1, wherein: In S1, select a grinding wheel with a mesh size of ≥800, a grinding wheel feed of ≤0.5 mm / min, and a crystal movement rate of ≤3 mm / min.

3. The method for controlling surface defects of a gallium antimonide polished wafer according to claim 1, wherein: A solution with a pH of 5-6 is prepared using an inorganic acid solution, a buffer, and high-purity water with a resistivity of 18 megohm-cm. The edge of the chamfered wafer is chemically etched at 18-24°C for 20-30 seconds, then rinsed with high-purity water and dried. The wafer edge is inspected with the naked eye under a fluorescent light and is considered qualified if there is no adsorbed matter, particles, or burrs on it.

4. The method for controlling surface defects of a gallium antimonide polished wafer according to claim 1, wherein: In S5, rough polishing is performed; the hardness of the polishing cloth selected is ≤80 Shore A, the particle size of the polishing liquid selected is ≤150nm and the pH value is 7-12, and the polishing liquid is added with an oxidizing agent to prepare a polishing liquid with a pH value of 8-12. The wafer is fixed on a wax-free pad and the polishing pressure is ≤200g / cm 2 , main disk speed 40-80r / min, polishing liquid flow ≤400ml / min, double-sided polishing, polishing removal amount controlled at 30-40 microns; after rough polishing, observe under fluorescent light that there are no scratches or saw marks defects before entering medium polishing; Medium polishing: The hardness of the polishing cloth should be ≤60 Shore A, the particle size of the polishing liquid should be ≤100nm and the pH value should be ≥8. After adding an oxidant to the polishing liquid, the pH value should be 9-10. The wafer should be fixed on a wax-free pad and the polishing pressure should be ≤150g / cm 2 , main disk speed 40-60r / min, polishing liquid flow 300-400ml / min, double-sided polishing, polishing removal ≤ 20 microns; after medium polishing, observe under 40W power strong light to ensure there are no scratches or saw marks, then proceed to fine polishing; Fine polishing: The hardness of the polishing cloth should be ≤40 Shore A, the compression elasticity should be 50-90%, and the opening diameter should be ≥200 mesh. The polishing liquid should contain an oxidant and the pH value should be 4-8. The wafer should be fixed on a wax-free pad and the polishing pressure should be ≤100g / cm 2 The main disk speed is 40-60r / min, the polishing liquid flow rate is 300-400ml / min, and both sides are polished. The polishing removal amount is ≤10 microns. After fine polishing, observe under a 40W strong light to ensure there are no scratches, bright scratches, dark scratches, NG, or chemical defects before entering the cleaning stage.

5. The method for controlling surface defects of a gallium antimonide polished wafer according to claim 1, wherein: In S6, after the wafer is polished, the lower plate is quickly flushed with water. The water gun pressure on both sides of the main plate is ≥1.5kg. The megasonic wave-assisted high-purity water gun flushes the surface in different directions for ≤30S. The water flow direction is consistent and there must be no backflow of flushing water.

6. The method for controlling surface defects of a gallium antimonide polished wafer according to claim 1, wherein: In S8, under a 40W strong light and a 20x microscope, the wafer surface is inspected from different angles for dark scratches, dirty spots, dark spots, potion, and potion dirt defects.

7. The method for controlling surface defects of a gallium antimonide polished wafer according to claim 1, wherein: In S9, the wafer storage room is a Class 100 environment, with room temperature controlled at 18-22°C and humidity controlled at ≤60%.

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