A method for producing a polished wafer free of etch pits

Abstract

The present application relates to the technical field of silicon wafer processing, in particular to a method for preparing a non-etching pit polished wafer, comprising the following steps: slicing, chamfering, grinding, chemical polishing, normal pressure chemical vapor deposition, end face processing, edge polishing, single side polishing and final cleaning. Most surface defects are removed through multiple rough polishing, the surface is further refined through middle polishing, and extremely high surface smoothness and flatness are achieved through fine polishing; prolonging the middle and fine polishing time helps to process all tiny defects and reduce etching pits on the product. Cerium dioxide and benzotriazole are added in the original solution because cerium dioxide has good hardness and wear resistance, can remove the unevenness on the surface of the material, and benzotriazole can form a protective film on the metal surface, which helps to reduce tiny scratches or defects in the polishing process, so as to obtain better surface integrity, thereby improving the consistency and efficiency of polishing.

Description

Technical Field

[0001] This invention belongs to the field of silicon wafer processing technology, and specifically relates to a method for preparing a polished wafer without corrosion pits. Background Technology

[0002] For silicon wafers, polishing is a necessary process. Its purpose is to: 1. remove the micro-damage layer on the surface of the silicon wafer; 2. ensure that the overall thickness and local thickness of the silicon wafer are sufficiently consistent; and 3. ensure consistent surface roughness and surface condition. Currently, the 8-inch silicon wafer polishing industry generally uses the chemical mechanical polishing method, which is usually divided into several steps: rough polishing and medium-fine polishing. During the polishing process, each step has its own function, and the polishing fluid and polishing cloth used in each step are different, resulting in different processing characteristics.

[0003] This invention specifically relates to the processing of 8-inch silicon polished wafers. Existing 8-inch silicon wafer processing uses the 221 process. The 221 process is characterized by requiring two rough polishing passes to remove 15 micrometers, and approximately 7.5 micrometers per machine. The polishing temperature is approximately 36℃~37℃. High temperatures accelerate the chemical reaction rate, especially for N-type wafers, leading to severe corrosion pits and affecting the quality of the polished wafer. To avoid producing silicon wafers with corrosion pits under existing support systems, equipment, and auxiliary materials, it is necessary to improve the polishing temperature and reduce the impact of rough polishing on the surface condition of the silicon wafer. Ensuring a pit-free surface after polishing is the problem this invention aims to solve. Therefore, this invention provides a method for preparing pit-free polished wafers. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing a corrosion-free polished disc, so as to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides a method for preparing a corrosion-free polished sheet, comprising the following steps:

[0006] S1.1. Use a laser cutting machine to cut silicon ingots into silicon wafers. The laser power is 50-200W, the cutting speed is 100-500mm / s, and the coolant flow rate is 5-20L / min.

[0007] S1.2 Place the silicon wafer on the chamfering machine, and cut it at a speed of 1000-1500 rpm and an angle of 30-60° close to the edge of the silicon wafer.

[0008] S1.3 First, use silicon carbide abrasive with a particle size of 20-40μm to coarsely grind the silicon wafer at a speed of 100-500rpm and a grinding pressure of 1-2kg / cm. 2The grinding time is 10-30 minutes; after rough grinding, the silicon wafer is ultrasonically cleaned with deionized water.

[0009] The silicon wafer is then finely ground using silicon carbide abrasive with a particle size of 5-10 μm at a grinding speed of 100-300 rpm and a grinding pressure of 0.5-1 kg / cm². 2 Time: 30-60 minutes;

[0010] S1.4. Immerse the silicon wafer in a 30% hydrogen peroxide solution for 1-2 minutes, then rinse with deionized water; fix the cleaned silicon wafer on a polishing machine and polish for 1-10 minutes.

[0011] After polishing, rinse with deionized water for 5-10 minutes, then dry with nitrogen gas at a pressure of 0.2-0.3 MPa.

[0012] S1.5 Place the silicon wafer in an atmospheric pressure chemical vapor deposition equipment, heat the silicon wafer to 300-500℃, introduce silicon source gas and oxygen source gas into the reaction chamber, and the deposition time is 30-90 minutes;

[0013] After deposition, the silicon wafer is allowed to cool naturally to room temperature in the reaction chamber. After cooling, it is ultrasonically cleaned at a frequency of 20-40kHz for 3-5 minutes, and then dried with nitrogen gas at a pressure of 0.2-0.3MPa.

[0014] S1.6 Place the silicon wafer in the etching solution and etch it at room temperature for 1-2 minutes, stirring gently at a speed of 100-200 rpm.

[0015] The etched silicon wafer is mounted on a polishing machine. The polishing pressure is 0.1-0.5MPa, the polishing speed is 50-150rpm, and the polishing time is 10-30min. After polishing, it is rinsed with deionized water and vacuum dried at a temperature of 60-80℃ for 30-60min.

[0016] S1.7. Install the silicon wafer on the polishing machine, perform rough polishing first, and then fine polishing. After polishing, rinse the edges of the silicon wafer with deionized water for 5-10 minutes, and then dry it with hot air at a temperature of 40-60℃ for 30-60 minutes.

[0017] S1.8 Place the silicon wafer on the polishing machine, set the polishing pressure to 0.1-0.5MPa, the rotation speed to 50-150rpm, and the polishing fluid flow rate to 5-10ml / min;

[0018] Polishing is performed by sequentially applying three rough polishing passes, one medium polishing pass, and one fine polishing pass.

[0019] Rinse with deionized water for 10-20 minutes, then vacuum dry at 60-80℃ for 30-60 minutes.

[0020] S1.9. The silicon wafer is ultrasonically cleaned with deionized water at a frequency of 30-50kHz for 5-10 minutes, and then vacuum dried at a temperature of 60-80℃ for 30-60 minutes to obtain a polished wafer without corrosion pits.

[0021] Preferably, in step S1.2, the cutting speed is 1000-3000 rpm and the feed rate is 0.01-0.1 mm / revolution.

[0022] Preferably, in step S1.3, the ultrasonic cleaning uses an ultrasonic frequency of 20-40kHz and a cleaning time of 5-10min.

[0023] Preferably, in step S1.5, the flow rate of the silicon source gas is 10-50 sccm, and the flow rate of the oxygen source gas is 50-200 sccm.

[0024] Preferably, in step S1.6, the corrosive solution is a mixture of hydrofluoric acid and nitric acid, with the hydrofluoric acid having a mass percentage concentration of 40% and the nitric acid having a mass percentage concentration of 49%.

[0025] Preferably, in step S1.7, the coarse polishing speed is 1500-2000 rpm, the pressure is 0.3-0.5 MPa, and the polishing time is 10-30 min; the fine polishing speed is 800-1500 rpm, the pressure is 0.1-0.3 MPa, and the polishing time is 5-15 min.

[0026] Preferably, in step S1.8, the coarse polishing speed is 1500-2000 rpm, the pressure is 0.3-0.5 MPa, the processing time is 5-7 min, and the processing temperature is 33-34℃; the medium polishing speed is 1000-1500 rpm, the pressure is 0.2-0.4 MPa, the fine polishing speed is 800-1500 rpm, the pressure is 0.1-0.3 MPa, the medium and fine polishing times are both 8-10 min, and the polishing pH value is 9-12.

[0027] Preferably, in step S1.8, the polishing slurry is prepared as follows;

[0028] S1.81. Add cerium dioxide powder with a particle size of 50-500nm to the original solution NP6504 and GLANZOX-3000LA, and stir continuously at a stirring speed of 100-300rpm to ensure that the cerium dioxide powder can be uniformly dispersed in the original solution.

[0029] S1.82. Dissolve benzotriazole in deionized water and slowly add it dropwise to the stock solution in S1.1 at a rate of 15-20 drops per minute. Continue stirring to ensure thorough mixing and obtain the mixed stock solution.

[0030] S1.83. Mix the original mixed solution with deionized water at a ratio of 1:10 to 1:30, and then perform ultrasonic treatment to obtain the polishing solution.

[0031] Preferably, in step S1.82, the stirring speed is 100-300 rpm and the stirring time is 10-20 min.

[0032] Preferably, in S1.83, the ultrasonic power is set to 100-500W, the frequency is 20-40kHz, and the processing time is 10-30min.

[0033] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0034] 1. A method for preparing a corrosion-pit-free polished disc involves polishing with three rough polishing passes, one intermediate polishing pass, and one fine polishing pass, with extended intermediate and fine polishing times. Multiple rough polishing passes remove most surface defects and unevenness, laying the foundation for subsequent finer polishing. Intermediate polishing further refines the surface, removing smaller scratches and pits. Fine polishing focuses on achieving extremely high surface smoothness and flatness. While rapidly removing material during the rough polishing stage, some minor scratches or pits may be introduced. These defects can be gradually eliminated through subsequent intermediate and fine polishing steps. Extending the intermediate and fine polishing times helps ensure that all minor defects are thoroughly addressed, thereby reducing corrosion pits on the final product.

[0035] 2. In a method for preparing a corrosion-free polishing pad, cerium dioxide and benzotriazole are added to the polishing slurry NP6504 and GLANZOX-3000LA. This is because cerium dioxide has good hardness and wear resistance, effectively removing uneven parts of the material surface, thereby improving polishing efficiency; its relatively small and uniform particle size helps achieve a smoother and finer surface treatment effect; benzotriazole is an excellent corrosion inhibitor that can prevent metal surfaces from being corroded and maintain material properties; by forming a protective film covering the metal surface, it helps reduce micro-scratches or defects during the polishing process, thereby obtaining better surface integrity; it also helps stabilize the polishing slurry system, preventing unnecessary chemical reactions of certain components and extending the effective service life of the polishing slurry; ultrasonic treatment promotes the uniform dispersion of particles in the polishing slurry, making cerium dioxide and benzotriazole more evenly distributed in the solution, thereby improving the consistency and efficiency of polishing. Attached Figure Description

[0036] Figure 1The polishing sheet prepared by the process of Comparative Example 1 in this invention;

[0037] Figure 2 The polishing sheet prepared by the process of Comparative Example 2 in this invention;

[0038] Figure 3 The polishing sheet prepared by the process of Comparative Example 3 in this invention;

[0039] Figure 4 This is a polishing sheet prepared using the process of preferred embodiment 1 of the present invention. Detailed Implementation

[0040] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0041] The present invention provides a method for preparing a corrosion-free polished sheet, comprising the following steps:

[0042] S1.1. Use a laser cutting machine to cut silicon ingots into silicon wafers. The laser power is 50-200W, the cutting speed is 100mm / s-500mm / s, and the coolant flow rate is 5-20L / min.

[0043] S1.2 Place the silicon wafer on the chamfering machine. The cutter cuts at a speed of 1000-1500 rpm and an angle of 30-60° close to the edge of the silicon wafer. The cutting speed is 1000-3000 rpm and the feed rate is 0.01-0.1 mm / revolution.

[0044] S1.3 First, use silicon carbide abrasive with a particle size of 20-40μm to coarsely grind the silicon wafer at a speed of 100-500rpm and a grinding pressure of 1-2kg / cm. 2 The time is 10-30 minutes; after rough grinding, the silicon wafer is ultrasonically cleaned with deionized water. The ultrasonic cleaning frequency is 20-40 kHz and the cleaning time is 5-10 minutes.

[0045] The silicon wafer is then finely ground using silicon carbide abrasive with a particle size of 5-10 μm at a grinding speed of 100-300 rpm and a grinding pressure of 0.5-1 kg / cm². 2 Time: 30-60 minutes;

[0046] S1.4. Immerse the silicon wafer in a 30% hydrogen peroxide solution for 1-2 minutes, then rinse with deionized water; fix the cleaned silicon wafer on a polishing machine and polish for 1-10 minutes.

[0047] After polishing, rinse with deionized water for 5-10 minutes, then dry with nitrogen gas at a pressure of 0.2-0.3 MPa.

[0048] S1.5 Place the silicon wafer in the atmospheric pressure chemical vapor deposition equipment, heat the silicon wafer to 300-500℃, introduce the silicon source gas at a flow rate of 10-50 sccm and the oxygen source gas at a flow rate of 50-200 sccm into the reaction chamber, and the deposition time is 30-90 min.

[0049] After deposition, the silicon wafer is allowed to cool naturally to room temperature in the reaction chamber. After cooling, it is ultrasonically cleaned at a frequency of 20-40kHz for 3-5 minutes, and then dried with nitrogen gas at a pressure of 0.2-0.3MPa.

[0050] S1.6 Place the silicon wafer in the etching solution and etch it at room temperature for 1-2 minutes, stirring gently at a speed of 100-200 rpm; the etching solution is a mixture of 40% hydrofluoric acid and 49% nitric acid by mass percentage.

[0051] The etched silicon wafer is mounted on a polishing machine. The polishing pressure is 0.1-0.5MPa, the polishing speed is 50-150rpm, and the polishing time is 10-30min. After polishing, it is rinsed with deionized water and vacuum dried at a temperature of 60-80℃ for 30-60min.

[0052] S1.7. Install the silicon wafer on the polishing machine and perform rough polishing first, with a rotation speed of 1000-2000 rpm, a pressure of 0.2-0.5 MPa, and a polishing time of 10-30 min; then perform fine polishing, with a rotation speed of 800-1500 rpm, a pressure of 0.1-0.3 MPa, and a polishing time of 5-15 min.

[0053] After polishing, rinse the edges of the silicon wafer with deionized water for 5-10 minutes, and then dry with hot air at a temperature of 40-60℃ for 30-60 minutes.

[0054] S1.8 Place the silicon wafer on the polishing machine, set the polishing pressure to 0.1-0.5MPa, the rotation speed to 50-150rpm, and the polishing fluid flow rate to 5-10ml / min;

[0055] The polishing process involves three rounds of rough polishing, one round of medium polishing, and one round of fine polishing. The rough polishing speed is 1500-2000 rpm, the pressure is 0.3-0.5 MPa, the processing time is 5-7 min, and the processing temperature is 33-34℃. The medium polishing speed is 1000-1500 rpm, the pressure is 0.2-0.4 MPa, and the fine polishing speed is 800-1500 rpm, the pressure is 0.1-0.3 MPa, and the medium and fine polishing times are both 8-10 min. The polishing pH value is 9-12.

[0056] Rinse with deionized water for 10-20 minutes, then vacuum dry at 60-80℃ for 30-60 minutes.

[0057] S1.9. The silicon wafer is ultrasonically cleaned with deionized water at a frequency of 30-50kHz for 5-10 minutes, and then vacuum dried at a temperature of 60-80℃ for 30-60 minutes to obtain a polished wafer without corrosion pits.

[0058] In S1.8, the specific preparation of the composite polishing liquid is as follows;

[0059] S1.81. Add cerium dioxide powder with a particle size of 50-500nm to the original solution NP6504 and GLANZOX-3000LA, and stir continuously at a stirring speed of 100-300rpm to ensure that the cerium dioxide powder can be uniformly dispersed in the original solution.

[0060] S1.82. Dissolve benzotriazole in deionized water and slowly add it dropwise to the stock solution in S1.1 at a rate of 15-20 drops per minute. Continue stirring at a speed of 100-300 rpm for 10-20 minutes to ensure thorough mixing and obtain the mixed stock solution.

[0061] S1.83. Mix the original mixed solution with deionized water at a ratio of 1:10 to 1:30, and then perform ultrasonic treatment. Set the ultrasonic power to 100-500W, the frequency to 20-40kHz, and the treatment time to 10-30min to obtain the polishing solution.

[0062] The NP6504 stock solution is a mixture, and its main components include water (CAS: 7732-18-5, mass concentration 60-70%), silica (CAS: 7631-86-9, mass concentration 25.0-35.0%), diethyleneimine (CAS: 110-85-0, mass concentration 1.0-7.0%), tetramethylammonium hydroxide (CAS: 75-59-2, mass concentration 1.0-5.0%), methanol (CAS: 67-56-1, mass concentration 0.1-1.0%), and carboxyalkylamine (mass concentration 0.1-1.0%).

[0063] GLANZOX-3000LA is a mixture, with the main components being approximately 10% silica, less than 1% cellulose, less than 1% ammonia, and more than 88% water.

[0064] Example 1: A method for preparing a corrosion-free polished sheet according to the present invention includes the following steps:

[0065] S1.1. Use a laser cutting machine to cut silicon ingots into silicon wafers. The laser power is 150W, the cutting speed is 200mm / s, and the coolant flow rate is 15L / min.

[0066] S1.2 Place the silicon wafer on the chamfering machine. The cutter cuts at a speed of 1000 rpm and an angle of 45° close to the edge of the silicon wafer. The cutting speed is 2000 rpm and the feed rate is 0.05 mm / revolution.

[0067] S1.3. First, use silicon carbide abrasive with a particle size of 20μm to coarsely grind the silicon wafer at a speed of 300rpm and a grinding pressure of 1.5kg / cm. 2 The grinding process takes 20 minutes. After the rough grinding is completed, the silicon wafer is ultrasonically cleaned with deionized water at a frequency of 40 kHz for 10 minutes.

[0068] The silicon wafer is then finely ground using silicon carbide abrasive with a particle size of 6μm at a grinding speed of 200 rpm and a grinding pressure of 0.5 kg / cm². 2 Time: 60 minutes;

[0069] S1.4. Immerse the silicon wafer in a 30% hydrogen peroxide solution for 2 minutes, then rinse with deionized water; fix the cleaned silicon wafer on a polishing machine and polish for 10 minutes.

[0070] After polishing, rinse with deionized water for 10 minutes, and then dry the cleaned silicon wafer with nitrogen gas at a pressure of 0.3 MPa.

[0071] S1.5 Place the silicon wafer in an atmospheric pressure chemical vapor deposition equipment, heat the silicon wafer to 500°C, use silicon source gas at a flow rate of 30 sccm, introduce oxygen source gas at a flow rate of 50 sccm, and deposit for 90 min.

[0072] After deposition, the silicon wafer is allowed to cool naturally to room temperature in the reaction chamber; after cooling, it is ultrasonically cleaned at a frequency of 40 kHz for 5 minutes, and then dried with nitrogen gas at a pressure of 0.3 MPa.

[0073] S1.6 Place the silicon wafer in the etching solution and etch it at room temperature for 2 minutes, stirring gently at a speed of 200 rpm; the etching solution is a mixture of 40% hydrofluoric acid and 49% nitric acid by mass percentage.

[0074] The etched silicon wafer was mounted on a polishing machine. The polishing pressure was 0.5 MPa, the polishing speed was 100 rpm, and the polishing time was 30 min. After polishing, it was rinsed with deionized water and vacuum dried at 80℃ for 60 min.

[0075] S1.7. Install the silicon wafer on the polishing machine and perform rough polishing first at a speed of 1200 rpm and a pressure of 0.5 MPa for 30 minutes; then perform fine polishing at a speed of 800 rpm and a pressure of 0.3 MPa for 15 minutes.

[0076] After polishing, rinse the edges of the silicon wafer with deionized water for 10 minutes, and then dry it with hot air at 60°C for 60 minutes.

[0077] S1.8 Place the silicon wafer on the polishing machine, set the polishing pressure to 0.5MPa, the rotation speed to 150rpm, and the polishing fluid flow rate to 10ml / min;

[0078] The polishing process involved three rounds of rough polishing, one round of medium polishing, and one round of fine polishing. The rough polishing speed was 1500 rpm, the pressure was 0.5 MPa, the processing time was 6 min, and the processing temperature was 34℃. The medium polishing speed was 1000 rpm, the pressure was 0.3 MPa, and the fine polishing speed was 800 rpm, the pressure was 0.1 MPa, and the medium and fine polishing times were both 9 min. The polishing pH value was 11.

[0079] Rinse with deionized water for 20 minutes, then vacuum dry at 80°C for 60 minutes.

[0080] S1.9. The silicon wafer is ultrasonically cleaned with deionized water at a frequency of 50 kHz for 10 min, and then vacuum dried at a temperature of 80 ℃ for 60 min to obtain a polished wafer without corrosion pits.

[0081] In step S1.8, the polishing slurry is prepared as follows;

[0082] S1.81. Add cerium dioxide powder with a particle size of 50-500nm to the original solution NP6504 and GLANZOX-3000LA, and stir continuously at a stirring speed of 200rpm to ensure that the cerium dioxide powder can be uniformly dispersed in the original solution.

[0083] S1.82. Dissolve benzotriazole in deionized water and slowly add it dropwise at 15 drops per minute to the stock solution in S1.1. Continue stirring at 150 rpm for 20 minutes to ensure thorough mixing and obtain the mixed stock solution.

[0084] S1.83. Mix the original mixed solution with deionized water at a ratio of 1:20, and then perform ultrasonic treatment. Set the ultrasonic power to 300W, the frequency to 40kHz, and the treatment time to 30min to obtain the polishing solution.

[0085] Example 2: A method for preparing a corrosion-free polished sheet according to the present invention includes the following steps:

[0086] S1.1. Use a laser cutting machine to cut silicon ingots into silicon wafers. The laser power is 150W, the cutting speed is 200mm / s, and the coolant flow rate is 15L / min.

[0087] S1.2 Place the silicon wafer on the chamfering machine. The cutter cuts at a speed of 1000 rpm and an angle of 45° close to the edge of the silicon wafer. The cutting speed is 2000 rpm and the feed rate is 0.05 mm / revolution.

[0088] S1.3. First, use silicon carbide abrasive with a particle size of 20μm to coarsely grind the silicon wafer at a speed of 300rpm and a grinding pressure of 1.5kg / cm. 2 The grinding process takes 20 minutes. After the rough grinding is completed, the silicon wafer is ultrasonically cleaned with deionized water at a frequency of 40 kHz for 10 minutes.

[0089] The silicon wafer is then finely ground using silicon carbide abrasive with a particle size of 6μm at a grinding speed of 200 rpm and a grinding pressure of 0.5 kg / cm². 2 Time: 60 minutes;

[0090] S1.4. Immerse the silicon wafer in a 30% hydrogen peroxide solution for 2 minutes, then rinse with deionized water; fix the cleaned silicon wafer on a polishing machine and polish for 10 minutes.

[0091] After polishing, rinse with deionized water for 10 minutes, and then dry the cleaned silicon wafer with nitrogen gas at a pressure of 0.3 MPa.

[0092] S1.5 Place the silicon wafer in an atmospheric pressure chemical vapor deposition equipment, heat the silicon wafer to 500°C, use silicon source gas at a flow rate of 30 sccm, introduce oxygen source gas at a flow rate of 50 sccm, and deposit for 90 min.

[0093] After deposition, the silicon wafer is allowed to cool naturally to room temperature in the reaction chamber; after cooling, it is ultrasonically cleaned at a frequency of 40 kHz for 5 minutes, and then dried with nitrogen gas at a pressure of 0.3 MPa.

[0094] S1.6 Place the silicon wafer in the etching solution and etch it at room temperature for 2 minutes, stirring gently at a speed of 200 rpm; the etching solution is a mixture of 40% hydrofluoric acid and 49% nitric acid by mass percentage.

[0095] The etched silicon wafer was mounted on a polishing machine. The polishing pressure was 0.5 MPa, the polishing speed was 100 rpm, and the polishing time was 30 min. After polishing, it was rinsed with deionized water and vacuum dried at 80℃ for 60 min.

[0096] S1.7. Install the silicon wafer on the polishing machine and perform rough polishing first at a speed of 1200 rpm and a pressure of 0.5 MPa for 30 minutes; then perform fine polishing at a speed of 800 rpm and a pressure of 0.3 MPa for 15 minutes.

[0097] After polishing, rinse the edges of the silicon wafer with deionized water for 10 minutes, and then dry it with hot air at 60°C for 60 minutes.

[0098] S1.8 Place the silicon wafer on the polishing machine, set the polishing pressure to 0.5MPa, the rotation speed to 150rpm, and the polishing fluid flow rate to 10ml / min;

[0099] The polishing process involved three rounds of rough polishing, one round of medium polishing, and one round of fine polishing. The rough polishing speed was 1500 rpm, the pressure was 0.5 MPa, the processing time was 6 min, and the processing temperature was 34℃. The medium polishing speed was 1000 rpm, the pressure was 0.3 MPa, and the fine polishing speed was 800 rpm, the pressure was 0.1 MPa, and the medium and fine polishing times were both 10 min. The polishing pH value was 11.

[0100] Rinse with deionized water for 20 minutes, then vacuum dry at 80°C for 60 minutes.

[0101] S1.9. The silicon wafer is ultrasonically cleaned with deionized water at a frequency of 50 kHz for 10 min, and then vacuum dried at a temperature of 80 ℃ for 60 min to obtain a polished wafer without corrosion pits.

[0102] In step S1.8, the polishing slurry is prepared as follows;

[0103] S1.81. Add cerium dioxide powder with a particle size of 50-500nm to the original solution NP6504 and GLANZOX-3000LA, and stir continuously at a stirring speed of 200rpm to ensure that the cerium dioxide powder can be uniformly dispersed in the original solution.

[0104] S1.82. Dissolve benzotriazole in deionized water and slowly add it dropwise at 15 drops per minute to the stock solution in S1.1. Continue stirring at 150 rpm for 20 minutes to ensure thorough mixing and obtain the mixed stock solution.

[0105] S1.83. Mix the original mixed solution with deionized water at a ratio of 1:20, and then perform ultrasonic treatment. Set the ultrasonic power to 300W, the frequency to 40kHz, and the treatment time to 30min to obtain the polishing solution.

[0106] Example 3: A method for preparing a corrosion-free polished sheet according to the present invention includes the following steps:

[0107] S1.1. Use a laser cutting machine to cut silicon ingots into silicon wafers. The laser power is 150W, the cutting speed is 200mm / s, and the coolant flow rate is 15L / min.

[0108] S1.2 Place the silicon wafer on the chamfering machine. The cutter cuts at a speed of 1000 rpm and an angle of 45° close to the edge of the silicon wafer. The cutting speed is 2000 rpm and the feed rate is 0.05 mm / revolution.

[0109] S1.3. First, use silicon carbide abrasive with a particle size of 20μm to coarsely grind the silicon wafer at a speed of 300rpm and a grinding pressure of 1.5kg / cm. 2 The grinding process takes 20 minutes. After the rough grinding is completed, the silicon wafer is ultrasonically cleaned with deionized water at a frequency of 40 kHz for 10 minutes.

[0110] The silicon wafer is then finely ground using silicon carbide abrasive with a particle size of 6μm at a grinding speed of 200 rpm and a grinding pressure of 0.5 kg / cm². 2 Time: 60 minutes;

[0111] S1.4. Immerse the silicon wafer in a 30% hydrogen peroxide solution for 2 minutes, then rinse with deionized water; fix the cleaned silicon wafer on a polishing machine and polish for 10 minutes.

[0112] After polishing, rinse with deionized water for 10 minutes, and then dry the cleaned silicon wafer with nitrogen gas at a pressure of 0.3 MPa.

[0113] S1.5 Place the silicon wafer in an atmospheric pressure chemical vapor deposition equipment, heat the silicon wafer to 500°C, use silicon source gas at a flow rate of 30 sccm, introduce oxygen source gas at a flow rate of 50 sccm, and deposit for 90 min.

[0114] After deposition, the silicon wafer is allowed to cool naturally to room temperature in the reaction chamber; after cooling, it is ultrasonically cleaned at a frequency of 40 kHz for 5 minutes, and then dried with nitrogen gas at a pressure of 0.3 MPa.

[0115] S1.6 Place the silicon wafer in the etching solution and etch it at room temperature for 2 minutes, stirring gently at a speed of 200 rpm; the etching solution is a mixture of 40% hydrofluoric acid and 49% nitric acid by mass percentage.

[0116] The etched silicon wafer was mounted on a polishing machine. The polishing pressure was 0.5 MPa, the polishing speed was 100 rpm, and the polishing time was 30 min. After polishing, it was rinsed with deionized water and vacuum dried at 80℃ for 60 min.

[0117] S1.7. Install the silicon wafer on the polishing machine and perform rough polishing first at a speed of 1200 rpm and a pressure of 0.5 MPa for 30 minutes; then perform fine polishing at a speed of 800 rpm and a pressure of 0.3 MPa for 15 minutes.

[0118] After polishing, rinse the edges of the silicon wafer with deionized water for 10 minutes, and then dry it with hot air at 60°C for 60 minutes.

[0119] S1.8 Place the silicon wafer on the polishing machine, set the polishing pressure to 0.5MPa, the rotation speed to 150rpm, and the polishing fluid flow rate to 10ml / min;

[0120] The polishing process involved three rounds of rough polishing, one round of medium polishing, and one round of fine polishing. The rough polishing speed was 1500 rpm, the pressure was 0.5 MPa, the processing time was 6 min, and the processing temperature was 34℃. The medium polishing speed was 1000 rpm, the pressure was 0.3 MPa, and the fine polishing speed was 800 rpm, the pressure was 0.1 MPa, and the medium and fine polishing times were both 8 min. The polishing pH value was 11.

[0121] Rinse with deionized water for 20 minutes, then vacuum dry at 80°C for 60 minutes.

[0122] S1.9. The silicon wafer is ultrasonically cleaned with deionized water at a frequency of 50 kHz for 10 min, and then vacuum dried at a temperature of 80 ℃ for 60 min to obtain a polished wafer without corrosion pits.

[0123] In step S1.8, the polishing slurry is prepared as follows;

[0124] S1.81. Add cerium dioxide powder with a particle size of 50-500nm to the original solution NP6504 and GLANZOX-3000LA, and stir continuously at a stirring speed of 200rpm to ensure that the cerium dioxide powder can be uniformly dispersed in the original solution.

[0125] S1.82. Dissolve benzotriazole in deionized water and slowly add it dropwise at 15 drops per minute to the stock solution in S1.1. Continue stirring at 150 rpm for 20 minutes to ensure thorough mixing and obtain the mixed stock solution.

[0126] S1.83. Mix the original mixed solution with deionized water at a ratio of 1:20, and then perform ultrasonic treatment. Set the ultrasonic power to 300W, the frequency to 40kHz, and the treatment time to 30min to obtain the polishing solution.

[0127] Example 4: A method for preparing a corrosion-free polished sheet according to the present invention includes the following steps:

[0128] S1.1. Use a laser cutting machine to cut silicon ingots into silicon wafers. The laser power is 150W, the cutting speed is 200mm / s, and the coolant flow rate is 15L / min.

[0129] S1.2 Place the silicon wafer on the chamfering machine. The cutter cuts at a speed of 1000 rpm and an angle of 45° close to the edge of the silicon wafer. The cutting speed is 2000 rpm and the feed rate is 0.05 mm / revolution.

[0130] S1.3. First, use silicon carbide abrasive with a particle size of 20μm to coarsely grind the silicon wafer at a speed of 300rpm and a grinding pressure of 1.5kg / cm. 2 The grinding process takes 20 minutes. After the rough grinding is completed, the silicon wafer is ultrasonically cleaned with deionized water at a frequency of 40 kHz for 10 minutes.

[0131] The silicon wafer is then finely ground using silicon carbide abrasive with a particle size of 6μm at a grinding speed of 200 rpm and a grinding pressure of 0.5 kg / cm². 2 Time: 60 minutes;

[0132] S1.4. Immerse the silicon wafer in a 30% hydrogen peroxide solution for 2 minutes, then rinse with deionized water; fix the cleaned silicon wafer on a polishing machine and polish for 10 minutes.

[0133] After polishing, rinse with deionized water for 10 minutes, and then dry the cleaned silicon wafer with nitrogen gas at a pressure of 0.3 MPa.

[0134] S1.5 Place the silicon wafer in an atmospheric pressure chemical vapor deposition equipment, heat the silicon wafer to 500°C, use silicon source gas at a flow rate of 30 sccm, introduce oxygen source gas at a flow rate of 50 sccm, and deposit for 90 min.

[0135] After deposition, the silicon wafer is allowed to cool naturally to room temperature in the reaction chamber; after cooling, it is ultrasonically cleaned at a frequency of 40 kHz for 5 minutes, and then dried with nitrogen gas at a pressure of 0.3 MPa.

[0136] S1.6 Place the silicon wafer in the etching solution and etch it at room temperature for 2 minutes, stirring gently at a speed of 200 rpm; the etching solution is a mixture of 40% hydrofluoric acid and 49% nitric acid by mass percentage.

[0137] The etched silicon wafer was mounted on a polishing machine. The polishing pressure was 0.5 MPa, the polishing speed was 100 rpm, and the polishing time was 30 min. After polishing, it was rinsed with deionized water and vacuum dried at 80℃ for 60 min.

[0138] S1.7. Install the silicon wafer on the polishing machine and perform rough polishing first at a speed of 1200 rpm and a pressure of 0.5 MPa for 30 minutes; then perform fine polishing at a speed of 800 rpm and a pressure of 0.3 MPa for 15 minutes.

[0139] After polishing, rinse the edges of the silicon wafer with deionized water for 10 minutes, and then dry it with hot air at 60°C for 60 minutes.

[0140] S1.8 Place the silicon wafer on the polishing machine, set the polishing pressure to 0.5MPa, the rotation speed to 150rpm, and the polishing fluid flow rate to 10ml / min;

[0141] The polishing process involved three rounds of rough polishing, one round of medium polishing, and one round of fine polishing. The rough polishing speed was 1500 rpm, the pressure was 0.5 MPa, the processing time was 6 min, and the processing temperature was 34℃. The medium polishing speed was 1000 rpm, the pressure was 0.3 MPa, and the fine polishing speed was 800 rpm, the pressure was 0.1 MPa, and the medium and fine polishing times were both 9 min. The polishing pH value was 12.

[0142] Rinse with deionized water for 20 minutes, then vacuum dry at 80°C for 60 minutes.

[0143] S1.9. The silicon wafer is ultrasonically cleaned with deionized water at a frequency of 50 kHz for 10 min, and then vacuum dried at a temperature of 80 ℃ for 60 min to obtain a polished wafer without corrosion pits.

[0144] In step S1.8, the polishing slurry is prepared as follows;

[0145] S1.81. Add cerium dioxide powder with a particle size of 50-500nm to the original solution NP6504 and GLANZOX-3000LA, and stir continuously at a stirring speed of 200rpm to ensure that the cerium dioxide powder can be uniformly dispersed in the original solution.

[0146] S1.82. Dissolve benzotriazole in deionized water and slowly add it dropwise at 15 drops per minute to the stock solution in S1.1. Continue stirring at 150 rpm for 20 minutes to ensure thorough mixing and obtain the mixed stock solution.

[0147] S1.83. Mix the original mixed solution with deionized water at a ratio of 1:20, and then perform ultrasonic treatment. Set the ultrasonic power to 300W, the frequency to 40kHz, and the treatment time to 30min to obtain the polishing solution.

[0148] Example 5: A method for preparing a corrosion-free polished sheet according to the present invention includes the following steps:

[0149] S1.1. Use a laser cutting machine to cut silicon ingots into silicon wafers. The laser power is 150W, the cutting speed is 200mm / s, and the coolant flow rate is 15L / min.

[0150] S1.2 Place the silicon wafer on the chamfering machine. The cutter cuts at a speed of 1000 rpm and an angle of 45° close to the edge of the silicon wafer. The cutting speed is 2000 rpm and the feed rate is 0.05 mm / revolution.

[0151] S1.3. First, use silicon carbide abrasive with a particle size of 20μm to coarsely grind the silicon wafer at a speed of 300rpm and a grinding pressure of 1.5kg / cm. 2 The grinding process takes 20 minutes. After the rough grinding is completed, the silicon wafer is ultrasonically cleaned with deionized water at a frequency of 40 kHz for 10 minutes.

[0152] The silicon wafer is then finely ground using silicon carbide abrasive with a particle size of 6μm at a grinding speed of 200 rpm and a grinding pressure of 0.5 kg / cm².2 Time: 60 minutes;

[0153] S1.4. Immerse the silicon wafer in a 30% hydrogen peroxide solution for 2 minutes, then rinse with deionized water; fix the cleaned silicon wafer on a polishing machine and polish for 10 minutes.

[0154] After polishing, rinse with deionized water for 10 minutes, and then dry the cleaned silicon wafer with nitrogen gas at a pressure of 0.3 MPa.

[0155] S1.5 Place the silicon wafer in an atmospheric pressure chemical vapor deposition equipment, heat the silicon wafer to 500°C, use silicon source gas at a flow rate of 30 sccm, introduce oxygen source gas at a flow rate of 50 sccm, and deposit for 90 min.

[0156] After deposition, the silicon wafer is allowed to cool naturally to room temperature in the reaction chamber; after cooling, it is ultrasonically cleaned at a frequency of 40 kHz for 5 minutes, and then dried with nitrogen gas at a pressure of 0.3 MPa.

[0157] S1.6 Place the silicon wafer in the etching solution and etch it at room temperature for 2 minutes, stirring gently at a speed of 200 rpm; the etching solution is a mixture of 40% hydrofluoric acid and 49% nitric acid by mass percentage.

[0158] The etched silicon wafer was mounted on a polishing machine. The polishing pressure was 0.5 MPa, the polishing speed was 100 rpm, and the polishing time was 30 min. After polishing, it was rinsed with deionized water and vacuum dried at 80℃ for 60 min.

[0159] S1.7. Install the silicon wafer on the polishing machine and perform rough polishing first at a speed of 1200 rpm and a pressure of 0.5 MPa for 30 minutes; then perform fine polishing at a speed of 800 rpm and a pressure of 0.3 MPa for 15 minutes.

[0160] After polishing, rinse the edges of the silicon wafer with deionized water for 10 minutes, and then dry it with hot air at 60°C for 60 minutes.

[0161] S1.8 Place the silicon wafer on the polishing machine, set the polishing pressure to 0.5MPa, the rotation speed to 150rpm, and the polishing fluid flow rate to 10ml / min;

[0162] The polishing process involved three rounds of rough polishing, one round of medium polishing, and one round of fine polishing. The rough polishing speed was 1500 rpm, the pressure was 0.5 MPa, the processing time was 6 min, and the processing temperature was 34℃. The medium polishing speed was 1000 rpm, the pressure was 0.3 MPa, and the fine polishing speed was 800 rpm, the pressure was 0.1 MPa, and the medium and fine polishing times were both 9 min. The polishing pH value was 9.

[0163] Rinse with deionized water for 20 minutes, then vacuum dry at 80°C for 60 minutes.

[0164] S1.9. The silicon wafer is ultrasonically cleaned with deionized water at a frequency of 50 kHz for 10 min, and then vacuum dried at a temperature of 80 ℃ for 60 min to obtain a polished wafer without corrosion pits.

[0165] In step S1.8, the polishing slurry is prepared as follows;

[0166] S1.81. Add cerium dioxide powder with a particle size of 50-500nm to the original solution NP6504 and GLANZOX-3000LA, and stir continuously at a stirring speed of 200rpm to ensure that the cerium dioxide powder can be uniformly dispersed in the original solution.

[0167] S1.82. Dissolve benzotriazole in deionized water and slowly add it dropwise at 15 drops per minute to the stock solution in S1.1. Continue stirring at 150 rpm for 20 minutes to ensure thorough mixing and obtain the mixed stock solution.

[0168] S1.83. Mix the original mixed solution with deionized water at a ratio of 1:20, and then perform ultrasonic treatment. Set the ultrasonic power to 300W, the frequency to 40kHz, and the treatment time to 30min to obtain the polishing solution.

[0169] Comparative Example 1: Using the method of Example 1, in step S1.8, polishing is performed by only two rough polishing, one medium polishing, and one fine polishing.

[0170] Comparative Example 2: The method of Example 1 was used to remove cerium dioxide and benzotriazole from the polishing solution.

[0171] Comparative Example 3: The method of Example 1 was used, with the time for medium and fine polishing set to 6 minutes.

[0172] The accompanying drawings of this invention ( Figure 1-4 Microscopic images of the polished surface states prepared by the original process (i.e., Comparative Example 1) and the process of the present invention embodiment were compared respectively. It can be seen that the original process (i.e., Comparative Example 1) Figure 1The surface of the polished sheet shown is relatively rough; among Examples 1-5, Example 1 is selected as the optimal example, wherein, from Figure 4 As can be seen from the process of the optimal embodiment 1, the surface of the polished sheet is relatively flat.

[0173] Through Examples 1-5, Comparative Example 1 and Comparative Example 3, and in combination Figure 1 , Figure 3 and Figure 4 As can be seen, the surface of the example is relatively smooth, mainly because it is polished using a process of three rough polishings, one medium polishing, and one fine polishing. The multiple rough polishings in the early stage can remove most surface defects and unevenness, laying the foundation for subsequent finer polishing. The medium polishing further refines the surface, removing smaller scratches and pits, while the fine polishing focuses on achieving extremely high surface smoothness and flatness. While the material is quickly removed during the rough polishing stage, some tiny scratches or pits may be introduced. Through the subsequent medium and fine polishing steps, these defects can be gradually eliminated. Extending the medium and fine polishing time helps to ensure that all minor defects are thoroughly treated, thereby reducing corrosion pits on the final product.

[0174] Three rough polishing stages can use relatively large abrasive particles and high cutting speeds to quickly remove excess material. This gradual rough polishing method is more efficient than a single rough polishing stage that removes a large amount of material, as a single rough polishing stage may lead to problems such as excessively high surface temperature and abrasive clogging. Medium and fine polishing stages are performed on the basis of rough polishing, so they require relatively less time. The overall process arrangement can make reasonable use of the cutting capabilities of abrasive particles of different sizes while ensuring surface quality, thereby improving the overall polishing efficiency.

[0175] The abrasives used in the three rough polishing processes are usually inexpensive. By performing rough polishing multiple times, the abrasives can be fully utilized, reducing the excessive consumption of high-cost fine polishing abrasives. Moreover, this process can reduce the need for rework due to unsatisfactory surface quality, thereby reducing production costs.

[0176] Through Examples 1-5, Comparative Example 2, and in combination Figure 2 and Figure 4 As can be seen, the surface of the example is relatively smooth, mainly because cerium dioxide is a highly efficient polishing abrasive. It has suitable hardness and chemical activity. During the polishing process, it can react chemically with the surface of the material being polished to form a soft reaction layer, thereby accelerating the removal of material and effectively improving the polishing rate. In the polishing liquid, cerium dioxide particles can be evenly distributed and contact the workpiece surface to perform fine grinding on the surface, effectively reducing scratches and surface defects, making the polished surface smoother and achieving a high surface finish.

[0177] Benzotriazole is an excellent metal corrosion inhibitor. During the polishing process, benzotriazole can prevent corrosion by forming a protective film on the metal surface. Benzotriazole can also be used as an additive to stabilize the chemical properties of polishing fluid, inhibit the decomposition or chemical reaction of certain components in the polishing fluid, and extend the service life of the polishing fluid.

[0178] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a corrosion-free polished disc, characterized in that, Includes the following steps: S1.

1. Use a laser cutting machine to cut silicon ingots into silicon wafers. The laser power is 50-200W, the cutting speed is 100-500mm / s, and the coolant flow rate is 5-20L / min. S1.2 Place the silicon wafer on the chamfering machine, and cut it at a speed of 1000-1500 rpm and an angle of 30-60° close to the edge of the silicon wafer. S1.3 First, use silicon carbide abrasive with a particle size of 20-40μm to coarsely grind the silicon wafer at a speed of 100-500rpm and a grinding pressure of 1-2kg / cm. 2 The grinding time is 10-30 minutes; after the rough grinding is completed, the silicon wafer is ultrasonically cleaned with deionized water. The silicon wafer is then finely ground using silicon carbide abrasive with a particle size of 5-10 μm at a grinding speed of 100-300 rpm and a grinding pressure of 0.5-1 kg / cm². 2 Time: 30-60 minutes; S1.

4. Immerse the silicon wafer in a 30% hydrogen peroxide solution for 1-2 minutes, then rinse with deionized water; fix the cleaned silicon wafer on a polishing machine and polish for 1-10 minutes. After polishing, rinse with deionized water for 5-10 minutes, then dry with nitrogen gas at a pressure of 0.2-0.3 MPa. S1.5 Place the silicon wafer in an atmospheric pressure chemical vapor deposition equipment, heat the silicon wafer to 300-500℃, introduce silicon source gas and oxygen source gas into the reaction chamber, and the deposition time is 30-90 minutes; After deposition, the silicon wafer is allowed to cool naturally to room temperature in the reaction chamber. After cooling, it is ultrasonically cleaned at a frequency of 20-40kHz for 3-5 minutes, and then dried with nitrogen gas at a pressure of 0.2-0.3MPa. S1.6 Place the silicon wafer in the etching solution and etch it at room temperature for 1-2 minutes, stirring gently at a speed of 100-200 rpm. The etched silicon wafer is mounted on a polishing machine. The polishing pressure is 0.1-0.5MPa, the polishing speed is 50-150rpm, and the polishing time is 10-30min. After polishing, it is rinsed with deionized water and vacuum dried at a temperature of 60-80℃ for 30-60min. S1.

7. Install the silicon wafer on the polishing machine, perform rough polishing first, and then fine polishing. After polishing, rinse the edges of the silicon wafer with deionized water for 5-10 minutes, and then dry it with hot air at a temperature of 40-60℃ for 30-60 minutes. S1.8 Place the silicon wafer on the polishing machine, set the polishing pressure to 0.1-0.5MPa, the rotation speed to 50-150rpm, and the polishing fluid flow rate to 5-10ml / min; Polishing is performed by sequentially applying three rough polishing passes, one medium polishing pass, and one fine polishing pass. Rinse with deionized water for 10-20 minutes, then vacuum dry at 60-80℃ for 30-60 minutes. S1.

9. The silicon wafer is ultrasonically cleaned with deionized water at a frequency of 30-50kHz for 5-10 minutes, and then vacuum dried at a temperature of 60-80℃ for 30-60 minutes to obtain a polished wafer without corrosion pits.

2. The method for preparing a corrosion-free polished disc according to claim 1, characterized in that: In step S1.2, the cutting speed is 1000-3000 rpm and the feed rate is 0.01-0.1 mm / revolution.

3. The method for preparing a corrosion-free polished disc according to claim 1, characterized in that: In S1.3, the ultrasonic cleaning uses an ultrasonic frequency of 20-40kHz and a cleaning time of 5-10min.

4. The method for preparing a corrosion-free polished disc according to claim 1, characterized in that: In step S1.5, the flow rate of the silicon source gas is 10-50 sccm, and the flow rate of the oxygen source gas is 50-200 sccm.

5. The method for preparing a corrosion-free polished disc according to claim 1, characterized in that: In S1.6, the corrosive solution is a mixture of hydrofluoric acid and nitric acid, with a mass percentage concentration of 40% for hydrofluoric acid and 49% for nitric acid.

6. The method for preparing a pit-free polished disc according to claim 1, characterized in that: In step S1.7, the coarse polishing speed is 1500-2000 rpm, the pressure is 0.3-0.5 MPa, and the polishing time is 10-30 min; the fine polishing speed is 800-1500 rpm, the pressure is 0.1-0.3 MPa, and the polishing time is 5-15 min.

7. The method for preparing a pit-free polished disc according to claim 1, characterized in that: In step S1.8, the coarse polishing speed is 1500-2000 rpm, the pressure is 0.3-0.5 MPa, the processing time is 5-7 min, and the processing temperature is 33-34℃; the medium polishing speed is 1000-1500 rpm, the pressure is 0.2-0.4 MPa, the fine polishing speed is 800-1500 rpm, the pressure is 0.1-0.3 MPa, the medium and fine polishing times are both 8-10 min, and the polishing pH value is 9-12.

8. The method for preparing a pit-free polished disc according to claim 1, characterized in that: In step S1.8, the polishing slurry is prepared as follows; S1.

81. Add cerium dioxide powder with a particle size of 50-500nm to the original solution NP6504 and GLANZOX-3000LA, and stir continuously at a stirring speed of 100-300rpm to ensure that the cerium dioxide powder can be uniformly dispersed in the original solution. S1.

82. Dissolve benzotriazole in deionized water and slowly add it dropwise to the stock solution of S1.1 at a rate of 15-20 drops per minute. Continue stirring to mix it thoroughly and evenly to obtain a mixed stock solution. S1.

83. Mix the original mixed solution with deionized water at a ratio of 1:10 to 1:30, and then perform ultrasonic treatment to obtain the polishing solution.

9. The method for preparing a pit-free polished disc according to claim 8, characterized in that: In step S1.82, the stirring speed is continued at 100-300 rpm, and the stirring time is 10-20 min.

10. The method for preparing a pit-free polished disc according to claim 8, characterized in that: In S1.83, the ultrasonic power is set to 100-500W, the frequency is 20-40kHz, and the processing time is 10-30min.

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