Technological method for controlling oxidation film of gallium antimonide polishing substrate slice of type II superlattice substrate

Abstract

The invention relates to a process method for controlling an oxide film of a gallium antimonide polished substrate slice of a class-II superlattice substrate. Aiming at the problem that a gallium antimonide material is high in chemical activity and easy to oxidize, a megasonic vibration device is additionally arranged in a medium polishing process, so that coagulation of a polishing solution is effectively controlled, and the surface roughness of a wafer is less than 0.5 nm. And in the final fine polishing process, a polishing method in which the chemical removal force is greater than the mechanical removal force is designed, so that the surface roughness of the wafer is further reduced to 0.3 nm, and the thickness of an oxide film is controlled to be less than or equal to 8.5 nm. A three-step wet etching process is adopted and comprises variable-temperature strong acid oxidation corrosion, low-temperature weak acid oxidation corrosion dissolution and room-temperature alkaline solution treatment, the thickness of an oxidation film on the surface of the wafer is smaller than or equal to 1.5 nm, and the surface uniformity of the wafer is larger than or equal to 97%. The thickness of the passivation layer is 2 nm, the passivation layer protects the surface of the gallium antimonide polished wafer from being oxidized, the state density of the surface of the wafer is effectively reduced, the carrier recombination center is reduced, the electrical performance of a device is improved, and the high requirement of a type-II superlattice epitaxial wafer for a substrate material can be met.

Description

Technical Field

[0001] The present invention belongs to the technical field of high-quality gallium antimonide wafer processing methods, and particularly relates to a process method for controlling the oxide film of a gallium antimonide polished substrate for a type-II superlattice substrate. Background Art

[0002] The production of semiconductor wafers mainly realizes the preparation of a high-quality surface through processing techniques such as polishing and cleaning. The GaSb material has high chemical activity and is prone to oxidation, requiring higher surface preparation processes and having higher processing difficulty compared to materials such as GaAs and InP. With the development of device epitaxial processes, the requirements for the surface performance of single wafers are becoming increasingly stringent, and the preparation of a high-quality surface has become the key to the development of GaSb single wafers.

[0003] Gallium antimonide is a key substrate material for type-II superlattice epitaxial wafers. The thickness and uniformity of the oxide film on the gallium antimonide substrate material directly affect the quality of the epitaxial wafer. First, theoretically analyzed, the oxide film on the gallium antimonide polished wafer is an oxide layer formed on the surface of the gallium antimonide polished wafer. This oxide film has an impact on the luminescence quality of the gallium antimonide material because the oxide layer cannot emit light but will affect the luminescence properties of gallium antimonide. In addition, the changes in the thickness, uniformity of the oxide film formed by polishing the gallium antimonide wafer and after wet etching will directly affect the stability, repeatability, consistency, etc. of the pre-treatment demoulding process for type-II superlattice epitaxial wafers, and even affect the quality of the epitaxial wafer, the quality of the device, and its luminescence properties.

[0004] The GaSb material has active chemical properties and will react in air and water to form oxides of Ga and Sb and elemental Sb. These oxides and dangling bonds will cause non-radiative recombination centers at the interface, resulting in the generation of interface leakage current and affecting device performance.

[0005] Therefore, improving the surface performance of GaSb wafers: the surface roughness of the wafer, the thickness and uniformity of the oxide film on the wafer surface, forming a gallium nitride thin layer on the wafer surface to cover the surface, replacing the original unstable oxide (Ga2O3), and suppressing oxidation and surface state defects have become the main problems studied in the present invention. Summary of the Invention

[0006] The present invention analyzes that the surface roughness and damage depth of the gallium antimonide wafer are directly related to the setting of chemical mechanical polishing process parameters and the cloth, pad, and liquid used in polishing. The thickness and uniformity distribution of the oxide film on the gallium antimonide wafer have a certain relationship with the etching method. Therefore, the present invention provides a process method for controlling the oxide film of a gallium antimonide polished substrate for a type-II superlattice substrate to solve the above technical problems from the process.

[0007] The technical solution provided by the present invention is: A process method for controlling the oxide film of a gallium antimonide polished substrate for a type-II superlattice substrate includes the following steps: Add a megasonic oscillation device in the medium polishing stage to use the megasonic energy to break up the colloid agglomeration in the polishing liquid; In the fine polishing stage, adopt a polishing method in which the chemical removal force is greater than the mechanical removal force; In the cleaning stage, adopt a three-step variable-temperature wet etching process: first, strong acid variable-temperature oxidation etching, the second step is weak acid oxidation low-temperature etching, and the third step is alkaline solution room-temperature treatment.

[0008] A further technical solution is that the megasonic oscillation device generates a high-frequency oscillation signal with a frequency ≥ 950KHZ through a megasonic generator, and converts it into a high-frequency mechanical oscillation through a transducer and conducts it to the abrasive in the polishing liquid to break up part of the formed colloid solution, inhibit the aggregation of nanoscale colloids, and then promote the uniform distribution of the solution on the polishing disc, so that the surface roughness of the wafer is relatively consistent. The surface roughness of the obtained gallium antimonide wafer is < 0.5nm.

[0009] A further technical solution is that in the fine polishing stage, use a polishing liquid composed of a polishing agent and high-purity deionized water, where the volume ratio of the polishing agent is ≤ 30%: high-purity water ≥ 70%, and the PH value is between 5-9; and the used polishing cloth has a Mohs hardness ≤ 40, a compression elastic modulus of 50-90%, and an aperture ≥ 200 mesh; the polishing pressure ≤ 80g / cm 2 , the flow rate ≥ 300ml / min, the rotation speed is 40-60 revolutions / min, and the polishing time is 5-10 minutes; thus meeting the requirement that the chemical removal force is greater than the mechanical removal force, achieving rapid polishing in a short time, reducing the surface roughness of the wafer to ≤ 0.3nm, and the thickness of the oxide film is 5-6nm.

[0010] A further technical solution is that in the three-step wet etching process, in the first step, an acid solution with a PH value ≤ 3 is used to etch and dissolve the front and back surfaces of the wafer. The etching and dissolution temperature is carried out in a variable temperature. First, etch and dissolve at 20-30 0 C for 3-5 seconds, then etch and dissolve at 80-100℃ for ≤ 20 seconds, and then etch and dissolve at 20-30 0 C for 3-5 seconds. On the one hand, it removes the organic matter on the wafer surface, and on the other hand, it forms soluble salts of the oxides of antimony and gallium, thereby removing the oxide layer.

[0011] A further technical solution is that in the three-step wet etching process, the second step is prepared by mixing a strongly oxidizing acid, an alkaline solution and a certain amount of high-purity deionized water, with a comprehensive PH ≤ 8. In order to slow down the reaction rate, the etching temperature is carried out at 0℃, and the etching time ≤ 10 seconds. The role of the second step is to etch and dissolve the metal impurities and organic matter on the surface of the GaSb wafer, improve the surface roughness, and obtain a GaSb wafer with a surface roughness < 0.3nm and an oxide film ≤ 2nm.

[0012] A further technical solution is as follows: in the three-step wet etching process, in the third step, a mixed solution of an alkaline solution and an organic solvent is used to prepare an etching solution with a comprehensive pH value between 8 and 10. The etching dissolution temperature is between 20 and 30 °C, and the etching dissolution time is ≤ 20 seconds. It can dissolve organic substances, remove particles and residues on the wafer surface. At the same time, a passivation layer about 2 nm thick is formed on the wafer surface to protect the wafer from environmental factors, prevent further oxidation on the surface during subsequent processing, extend the service time of the epitaxial wafer, and help to demold more easily during the subsequent epitaxial growth process, thereby improving the stability of device performance.

[0013] After being treated by the three-step wet etching process, the thickness of the oxide film on the gallium arsenide wafer is reduced from 8 - 8.5 nm to ≤ 1.5 nm, the uniformity of the oxide film reaches ≥ 97%, and the thickness of the GaNx passivation layer formed is 2 nm, which can meet the requirements of type II superlattice epitaxial wafers for the thickness and uniformity of the substrate oxide film. The process of this application has been solidified and transferred to production.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The present invention first introduces a megasonic oscillation device in the medium polishing stage, effectively solving the problem of colloid coagulation of the polishing liquid. It can effectively disperse the agglomerated particles formed by a colloidal solution of silica dioxide with a size of dozens of nanometers, promote the uniform distribution of silica dioxide molecules, and make the surface roughness of the wafer relatively consistent. The surface roughness of the obtained gallium antimonide wafer is < 0.5 nm.

[0015] 2. The present invention designs a final chemical mechanical polishing process method, in which the chemical removal force is greater than the mechanical removal force in a short time to quickly obtain a surface with low roughness, improving the polishing efficiency and quality. The surface roughness of the obtained gallium antimonide wafer is ≤ 0.3 nm, and the thickness of the oxide film is between 5 and 6 nm.

[0016] 3. The present invention innovatively designs a new wet cleaning process. The oxides on the surface and back are etched by a variable-temperature strong acid etching process to remove the remaining organic substances, inorganic substances and oxides on the wafer surface; the surface is oxidized and dissolved with a low-temperature weak acid to remove metal impurities and organic substances, obtaining a wafer with an oxide film ≤ 2 nm and a surface roughness < 0.3 nm; finally, it is treated with a room-temperature alkaline solution to remove the remaining organic particles, and a GaNx passivation layer with a thickness of 2 nm is formed. This passivation film can protect the material from environmental factors, such as the erosion of oxygen and moisture, thereby extending the service time of the epitaxial wafer. After being treated by the three-step wet etching process, the thickness of the oxide film on the gallium arsenide wafer is reduced from 8 - 8.5 nm to ≤ 1.5 nm, and the uniformity of the oxide film reaches ≥ 97%, which can meet the requirements of type II superlattice epitaxial wafers for the thickness and uniformity of the substrate oxide film. Description of the Drawings

[0017] Figure 1 For the prior art, the thickness of the oxide film on the wafer surface before cleaning after fine polishing is between 8.14 nm, and the non-uniformity is 6.81%.

[0018] Figure 2 For the polished wafer of the present application after wet etching, the thickness of the oxide film is between 1.25 nm, and the non-uniformity is 2.739%. Figure 3 The surface roughness Ra of the wafer after fine polishing measured by atomic force microscope is 0.1 nm.

[0019] Figure 4 Test by XSP photoelectron spectrometer: The significant N1s peak (binding energy is about 393 ev) corresponds to the Ga-N bond peak, and the thickness of the passivation film is 2 nm. Specific embodiments

[0020] To make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below with reference to specific embodiments and the accompanying drawings.

[0021] This application belongs to the category of manufacturing special equipment for semiconductor devices. Since gallium antimonide is the substrate material for II-type superlattice epitaxy, the surface roughness and damage depth of the wafer directly affect the quality of the epitaxial wafer. The thickness and uniformity of the oxide film on the wafer surface directly affect the stability and repeatability of the epitaxial pretreatment process. At the same time, more importantly, it also affects the light emission efficiency of the device.

[0022] We analyze that the surface roughness and damage depth of gallium antimonide wafers are directly related to the setting of chemical mechanical polishing process parameters and the polishing cloth, pad and liquid used. The thickness and uniformity distribution of the oxide film on gallium antimonide wafers are related to the etching method to a certain extent. Therefore, the above technical problems are solved from the process.

[0023] The specific embodiments of this application include the following steps: 1. The chemical mechanical polishing equipment for gallium antimonide wafers used is a SEEDFAM-32G single-sided polishing machine, and 2 sets of equipment are used.

[0024] 2. The gallium antimonide wafers implemented are 2 inches in diameter, with a thickness <550 μm, and the number is 20. The wafer surface is thinned by a grinding wheel (grinding wheel mesh number ≥ 6000). After thinning, chemical etching treatment is carried out (alkaline solution + oxidant + high-purity water, with a volume ratio of 1%: 2%: 7%, and the comprehensive pH value ≥ 7), the etching time ≤ 20 s, and the surface is smooth without stripes, scratches or gouges under a fluorescent lamp, and the roughness is about 3 nm.

[0025] 3. The thinned wafer first enters the medium polishing process. The medium polishing solution is composed of colloidal silica solution + oxidant + high-purity water. Among them, the particle size of the colloidal silica solution is ≤100nm, the PH value is ≥9, and the oxidant (hydrogen peroxide, sodium dichloroisocyanurate, sodium phosphate, sodium pyrophosphate, organic acids, inorganic acids...) and high-purity deionized water etc. are used to form the polishing solution, and their volume ratio is ≤10%:≤20%:≥70%, and the measured PH value is between 5-9.

[0026] 4. The prepared medium polishing solution is placed in a quartz barrel and fully mixed and stirred for a time ≥2 hours.

[0027] 5. A megasonic generator is set below the quartz barrel. Using the high-frequency oscillation signal generated by the megasonic generator, it is converted into high-frequency mechanical oscillation through a transducer and conducted to the abrasives in the polishing solution. The nano-abrasives in the polishing solution can break up some of the agglomerated colloidal solutions through high-frequency oscillation of ≥950KHZ, and also inhibit the aggregation of nano-scale colloids, thereby promoting the uniform distribution of the solution on the polishing disc. Also pay attention to selecting appropriate polishing process parameters, etc.

[0028] 6. There are two latex tubes in the quartz barrel connected to a peristaltic pump, and two latex tubes on the peristaltic pump are connected to a filter, thereby controlling the flow rate of the polishing solution.

[0029] 7. The polishing solution used in medium polishing is filtered by three ≤0.5μm filters in series, and the filter particle size decreases step by step for filtration.

[0030] 8. The solution after being filtered by the filter is connected to the solution inlet of the polishing machine by a latex hose to supply liquid to the polishing disc in a timely manner.

[0031] 9. The peristaltic pump shows the rotation speed of the pump. Its rotation speed corresponds to the liquid flow rate per unit time of the solution. By controlling the rotation speed of the peristaltic pump, the flow rate of the solution entering the polishing disc is monitored to qualitatively monitor the solution flow rate.

[0032] 10. The polishing cloth used for medium polishing of gallium antimonide wafers is a more suitable black damping cloth, and its Mohs hardness is ≤60. The wafer is fixed on a wax-free pad. The polishing solution passes through the peristaltic pump and three-stage filtration, and finally flows to the main disc through a latex tube at 300-400ml / min, and the pressure of the upper polishing disc is ≤150g / cm 2 , the rotation speed of the main disc is 40-60 / min, and the polishing removal amount is ≤20μm.

[0033] 11. During the polishing process, pay attention to monitoring the surface fluctuation of the megasonic-treated polishing solution, the rotation speed of the peristaltic pump, and the flow rate setting on the polishing machine, etc.

[0034] 12. After the gallium antimonide wafer is chemically mechanically polished, promptly turn off the megasonic device of the polishing liquid, quickly lift the tray, rinse with high-purity water for about 30 - 50 seconds, then place it under an overflowing water rinse, pick up the wafer with a vacuum suction pen, and then enter a spin dryer for drying under nitrogen protection, etc.

[0035] 13. Observe the surface of the wafer for shallow scratches, cloth marks, growth stripes, chemical stains, etc. under a strong light, and then enter the fine polishing process.

[0036] It should be noted that usually, the final polishing of gallium antimonide wafers is completed by chemical mechanical polishing. However, practice tells us that during this polishing process, if the mechanical force is relatively strong, the surface of the wafer is relatively rough and prone to dark scratches, growth lines, etc. If the chemical force is relatively strong, defects are likely to appear on the surface. To obtain a surface with relatively low roughness and good smoothness, it is necessary to adjust the balance point between chemical force and mechanical force in the process. The following steps 14 - 17 are the innovative steps of this application.

[0037] 14. Final fine polishing: Use a polishing liquid composed of a polishing agent and high-purity deionized water, where the volume ratio of the polishing agent ≤ 30%: high-purity water ≥ 70%, and the pH value is between 5 - 9. The polishing agent is one or several of hydrogen peroxide, potassium hypochlorite, sodium dichloroisocyanurate, organic acids, inorganic acids, sodium hypochlorite, tartaric acid, etc. Stir the polishing liquid for ≥ 2 hours.

[0038] 15. The polishing liquid is passed through a peristaltic pump and three-stage filtration, and finally flows onto the main tray through a latex tube at a rate of 300 - 400 ml / min.

[0039] 16. The black damping cloth used for fine polishing has a Mohs hardness ≤ 40, a compression elastic modulus of 50 - 90%, and an aperture ≥ 200 mesh.

[0040] 17. The wafer is fixed on a wax-free pad, the pressure on the upper polishing disc ≤ 80 g / cm 2 around, the rotational speed of the main tray is 40 - 60 / min, the polishing time is about 5 - 10 minutes, and the polishing removal amount is generally ≤ 5 μm or so. The above parameters achieve polishing with the chemical removal force greater than the mechanical removal force. The roughness of the polished wafer is ≤ 0.3 nm, and the thickness of the oxide film is between 5 - 6 nm.

[0041] 18. After polishing, quickly lift the tray, rinse with high-purity water for ≤ 30 seconds and then unload the tray, rinse with overflowing water, pick up the wafer with a vacuum suction pen and place it in a multi-wafer CASS, and then put it into a spin dryer for drying, and the drying time of the spin dryer is ≤ 60 seconds.

[0042] 19. Observe the surface of the above wafer for shallow scratches, cloth marks, growth stripes, chemical stains, etc. at different angles under a strong light.

[0043] 20. Mark the qualified wafers after inspection and transfer them to the "Cleaning Workshop" through the logistics window. Place the unqualified wafers in the designated area.

[0044] 21. After receiving the wafers, the cleaning workshop conducts surface treatment (the residence time of the wafers before cleaning ≤ 0.5 hours) 1) First, place the wafer on a single-piece clip. In the first step, use 100% inorganic acid with a pH value ≤ 3 (such as sulfuric acid, hydrofluoric acid, hydrochloric acid, nitric acid, phosphoric acid,...), and carry out etching treatment under the condition of variable temperature (from room temperature to high temperature and then back to room temperature). The room temperature is 20 - 30 0 °C, the high temperature is 80 - 100 0 °C, and then back to room temperature 20 - 30 0 °C. The time ranges from 3 - 5 s to ≤ 20 s and then back to 3 - 5 s. During the etching process, the clip swings uniformly back and forth to achieve an even etching solution. Finally, rinse with high-purity deionized water for ≤ 10 s and then enter the second-step cleaning.

[0045] The change in the temperature of the first-step wet etching can better control the etching process, ensure etching uniformity and surface quality. The room temperature stage is used to control the reaction rate, making the etching process stable, with the wafer surface wetted evenly. The high-temperature stage increases the reaction rate, accelerates the etching process, and can quickly remove pollutants, oxide layers, and organic substances, etc. Finally, in the room temperature stage, the reaction rate is reduced, and the temperature difference between the wafer surface and the high-purity water rinse is reduced, thereby protecting the wafer surface.

[0046] 2) Place the wafer in an acidic etching solution, which is composed of a strongly oxidizing inorganic acid as an oxidant (such as one of hydrochloric acid, nitric acid, glacial acetic acid, hydrocyanic acid, tartaric acid, and hydrogen peroxide), a basic solvent (such as ammonia water, ammonium hydroxide, sodium hydroxide, potassium hydroxide, ammonium hydroxide.....), and high-purity water. The volume ratio of the solution is inorganic acid < 10%, basic solvent < 20, and high-purity water > 70%. The pH value of the mixed solution ≤ 7, the etching time ≤ 10 s, the etching temperature is 0 °C, and the clip swings uniformly back and forth during the etching process to achieve an even etching solution. Rinse with high-purity deionized water for ≤ 10 s and then enter the third-step cleaning.

[0047] The function of the second-step wet etching process is: etch and dissolve the metal impurities and organic substances on the surface of the GaSb wafer, improve the surface roughness, and obtain a wafer with a surface roughness < 0.3 nm and an oxide layer ≤ 2 nm.

[0048] 3) Place the wafer in a solution combining an alkaline solution and an organic solvent. The alkaline solution can be one of sodium hydroxide, potassium hydroxide, ammonium hydroxide, and ammonia water, and the organic solution can be one of isopropyl alcohol, acetone, ethanol, and tetramethylammonium hydroxide. Among them, the volume ratio of the alkaline solution ≤ 10%, the organic solvent ≤ 20%, high-purity water ≥ 70, the pH value is 8 - 10, process at room temperature (20 - 30 °C) for ≤ 20 s, rinse with high-purity deionized water for ≤ 20 s, and then place the wafer in a single-wafer spin dryer to spin dry, with the spin-drying time approximately 60 seconds.

[0049] The function of the third-step wet etching process is as follows: Remove particles and residues on the wafer surface. At the same time, the combination of the alkaline solution and the organic solvent can play a role in the passivation process. The passivation layer forms a protective film on the wafer surface, reducing the surface state density. The nitrogen passivation layer involves the formation of nitrides or nitrogen-containing compounds. Gallium on the surface of gallium antimonide reacts with nitrogen in the solution to form a gallium nitride layer, and the organic solvent acts as a solvent or surfactant to help the reaction proceed uniformly and remove by-products.

[0050] GaSb is easily oxidized in air to form GaOx and SbOx. These oxides are unstable and non-uniform. Through the above-mentioned third-step process treatment, a more stable and dense nitride passivation layer can replace the oxide layer, achieving a reduction in surface states and improving device performance.

[0051] After being treated by the three-step wet etching process, the thickness of the oxide film on the gallium antimonide wafer decreases from 8 - 8.5 nm to ≤ 1.5 nm, and the uniformity of the oxide film reaches 97 - 99%. A GaNx passivation film of 2 nm is formed, which can meet the requirements of the II-class superlattice epitaxial wafer for the thickness and uniformity of the substrate oxide film. The process of this application has been solidified and transferred to production.

[0052] 22. Place the wafers in the cassette under a strong light at different angles to inspect surface scratches, dark scratches, dark spots, bright spots, chemical solutions, chemical stains, growth rings, and other items. Then observe the back surface scratches, scuffs, edge residues, chipping, and edge knocking of the wafer under a fluorescent lamp, mark the qualified wafers, and place them in the designated area.

[0053] 23. After the wafers are qualified, other parameters need to be detected: 1) Observe the surface defects of the wafer under a microscope at a magnification of 200 - 500 times and judge according to the standard to meet the customer requirements; Measure the thickness of the oxide film with a spectroscopic ellipsometer ES01A-U. Usually, the thickness of the oxide film on the polished gallium antimonide wafer before cleaning is between 8 - 8.5 nm, with an average value ≤ 8.5 nm and an average non-uniformity ≤ 5%. After cleaning the polished gallium antimonide wafer, the thickness of the oxide film is between 1.1 - 1.3, with an average value ≤ 1.25 nm and an average non-uniformity ≤ 3%. See Tables A and B for details. A: Oxide film on the polished gallium antimonide wafer before cleaning

[0054] B: Oxide film on the polished gallium antimonide wafer after cleaning

[0055] In the test of a high-sensitivity, high-resolution and non-destructive XSP photoelectron spectrometer, there is a significant N1s peak (binding energy of about 393 eV) corresponding to the Ga-N bond peak, which is measured to be about 2 nm.

[0056] The roughness of the wafer detected by an atomic force microscope is between 0.2 - 0.3 nm.

[0057] The total thickness variation (TTV) of the flatness tester is ≤ 5 μm, and the warp is ≤ 10 μm.

[0058] In the test of the SFS6200 particle size detector, the number of particles not exceeding 0.15 μm is no more than 90.

[0059] 24. Mark the wafers that pass the inspection, place them in a single wafer cassette, put the cassette in a double-layer aluminum foil, evacuate the inside, fill the outside with inert gas, pack them and store them in the warehouse, and place them in the designated area.

Claims

1. A process for controlling the oxide film of a polished gallium antimonide substrate of a type-II superlattice, characterized in that Including the following steps: Adding a megasonic oscillation device in the medium polishing stage to break up the colloid agglomeration in the polishing liquid by using the megasonic energy; Adopting a polishing method in the fine polishing stage where the chemical removal force is greater than the mechanical removal force; In the cleaning stage, adopting a three-step wet etching process: variable-temperature strong acid oxidation etching, low-temperature weak acid oxidation etching, and room-temperature alkaline solution treatment.

2. The process method for controlling the oxide film of the gallium antimonide lapping substrate of the II-type superlattice substrate according to claim 1, characterized in that, The megasonic oscillation device generates a high-frequency oscillation signal with a frequency ≥ 950KHZ through a megasonic generator, and converts it into a high-frequency mechanical oscillation through a transducer and conducts it to the abrasive in the polishing liquid.

3. The process method for controlling the oxide film of the gallium antimonide substrate polishing back film of type II superlattice according to claim 1, wherein, In the fine polishing stage, a polishing liquid composed of polishing agent and high-purity deionized water is used, where the volume ratio of the polishing agent is ≤30%: high-purity water ≥70%, and the pH value is between 5 and 9; and the polishing cloth used has a Mohs hardness ≤40, a compression elastic modulus of 50-90%, and an opening diameter ≥200 mesh; the polishing pressure ≤80 g / cm 2 , the flow rate ≥300 ml / min, the rotation speed is 40-60 revolutions / min, and the polishing time is 5-10 minutes.

4. The process method for controlling the oxide film of the gallium antimonide polished substrate of the II-type superlattice substrate according to claim 1, characterized in that, In the three-step wet etching process with different temperatures, in the first step, an acid solution with a pH value ≤ 3 is used to etch and dissolve the front and back surfaces of the wafer. The etching and dissolution temperature is carried out under variable temperature. The so-called variable temperature first etches and dissolves for 3 - 5 seconds at 20 - 30°C, then etches and dissolves for ≤ 20 seconds at 80 - 100°C, and then etches and dissolves for 3 - 5 seconds at 20 - 30°C.

5. The process method for controlling the oxide film of the gallium antimonide polished substrate of the II-class superlattice substrate according to claim 1, characterized in that, In the three-step wet etching process, the second step is prepared by adding a strongly oxidizing acid, an alkaline solution, and high-purity deionized water, with a comprehensive pH ≤ 8. In order to slow down the reaction rate, the etching temperature is carried out at 0°C, and the etching time ≤ 10 seconds.

6. The process method for controlling the oxide film of a gallium antimonide polished substrate of a type-II superlattice substrate according to claim 1, characterized in that In the three-step wet etching process, in the third step, a mixed solution of an alkaline solution and an organic solvent is used to prepare an etching solution with a comprehensive pH value between 8 - 10. The etching and dissolution temperature is between 20 - 30°C, and the etching and dissolution time ≤ 20 seconds.

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