Silicon alkali corrosion liquid for semiconductor industry and corrosion method thereof

Abstract

The invention discloses an alkali corrosion liquid for silicon in the semiconductor industry and a corrosion method of the alkali corrosion liquid. According to the alkali corrosion liquid, a corrosion method of slow acid corrosion and sufficient alkali corrosion is adopted, the surface roughness of the silicon wafer can be effectively reduced, in addition, in the alkali corrosion liquid, a surfactant, an active additive, sodium dodecyl polyoxyethylene ether sulfate and the like are matched with alkali, so that the surface tension of the alkali is further reduced, the corrosion rate is higher, and the service life of the silicon wafer is prolonged. The surface tension can be effectively reduced, the affinity of the etching liquid and a silicon substrate is improved, the selective etching capability to silicon dioxide in the etching process can be enhanced, corrosion to the silicon substrate is reduced, and a more uniform and accurate etching effect is achieved. Through measurement, the surface roughness Ra of the silicon wafer obtained by the corrosion method is less than or equal to 0.1 mu m, and the single metal cation is lt; and the corrosion rate can reach 1-1.5 microns / minute and is stabilized within + / -5%.

Description

Technical Field

[0001] The invention belongs to the technical field of silicon etching, and in particular relates to an alkaline etching solution for silicon used in the semiconductor industry and an etching method thereof. Background Art

[0002] Anisotropy, also known as "heterogeneity", refers to the property that the physical, chemical and other properties of an object vary with the measured direction. Silicon anisotropic etching is one of the key technologies for manufacturing micromechanical structures. Through anisotropic etching technology, single-crystal silicon devices with various shapes and sizes can be manufactured. The most common application area is integrated circuits, such as the manufacture of tuners, filters, sensors, etc. in microelectronic components and integrated circuits. In micro-electromechanical systems, anisotropic etching technology is also used to manufacture optical and mechanical devices. In addition, anisotropic etching technology can also produce structures such as micropores and microchannels, which are used to prepare microfluidic chips and microbial chips.

[0003] The main characteristics of silicon anisotropic etching are related to the etching rate, silicon crystal orientation, doping concentration and applied potential. This etching technology provides an appropriate method for device precision processing. It relies on adjusting the device structure to adapt it to the direction of the fast-etching crystal plane or the slow-etching crystal plane, and uses the characteristic that the etching rate depends on the impurity concentration and the applied potential to stop the corrosion in time.

[0004] Alkali etching is an anisotropic etching process. After etching, the surface of the silicon wafer is flat. Moreover, alkaline etching has the advantages of simple process, no stirring of the etching solution, controllable etching rate, relatively easy environmental treatment, non-toxicity, and waste liquid can be recycled. At present, polishing wafer manufacturers use alkaline etching in this process. There are two main types of commonly used alkaline etching solutions, one is inorganic alkaline corrosive agents, such as potassium hydroxide solution, and the other is organic alkaline corrosive agents, such as EPW (the abbreviation of ethylenediamine, phthalic acid and water). Among them, potassium hydroxide solution is widely used by polishing wafer manufacturers because of its mature process, low cost of etching solution, and fast corrosion rate. However, the conventional alkaline etching process also has limitations, such as its slow corrosion rate, and metal ions may remain on the surface. In particular, the surface of the single crystal silicon wafer after etching is rough, and it is easy to adsorb impurities, which will seriously affect the life and other parameters.

[0005] Patent 202010621821.2 discloses a method for preparing and etching a TMAH etching solution. The etching solution in the patent includes tetramethylammonium hydroxide, alcohols and water. The silicon oxide on the surface of the pattern to be etched on the single crystal silicon wafer is corroded cleanly, and then the single crystal silicon wafer is immersed in the heated TMAH silicon etching solution to complete the etching. This method is used in MEMS micromachining technology. After etching, the silicon wafer has no surface pyramids or orange peel effects, which meets the needs of semiconductor customers. It has the advantages of simple operation, precise control of etching depth, strong repeatability, low toxicity and low pollution, and easy to achieve batch production. However, this method still has the problems of uneven surface after etching and etching of aluminum mask. Summary of the invention

[0006] To overcome the shortcomings and deficiencies of the prior art, the primary purpose of the present invention is to provide an alkaline etching solution for silicon used in the semiconductor industry.

[0007] Another object of the present invention is to use the alkaline etching solution for silicon to be used in the semiconductor industry for etching.

[0008] The present invention is achieved in this way: an alkaline etching solution for silicon used in the semiconductor industry, the alkaline etching solution comprising the following components by mass: 40-50 parts of alkali, 2-3 parts of surfactant, 1-2 parts of sodium dodecyl polyoxyethylene ether sulfate, 0.1-0.4 parts of active additive and 70-80 parts of pure water.

[0009] Preferably, the base is selected from one or more of potassium hydroxide, sodium hydroxide, ammonium hydroxide, tetramethylammonium hydroxide, tetraethylammonium hydroxide, and tetrapropylammonium hydroxide.

[0010] Preferably, the base is tetramethylammonium hydroxide.

[0011] Preferably, the surfactant is selected from one or more of ethylene glycol, fatty alcohol polyoxyethylene ether, fatty amine polyoxyethylene ether, and lauryl alcohol polyoxyethylene ether.

[0012] Preferably, the active additive is selected from one or more of ammonium tetrafluoroborate, benzalkonium chloride, and sodium ammonium dodecyl sulfate.

[0013] The present invention further discloses a method for etching silicon for use in the semiconductor industry, the method comprising the following steps: (1) adding an acid etching solution and a single crystal silicon wafer into an acid etching machine, and performing root etching at a temperature of 45 to 75° C. for 2 to 6 minutes to remove the natural oxide layer of the surface pattern of the single crystal silicon wafer; wherein 10 to 20 parts by weight of hydrofluoric acid, 30 to 35 parts by weight of nitric acid, and 10 to 20 parts by weight of a fluoride salt are mixed and stirred uniformly to obtain the acid etching solution; (2) taking out the single crystal silicon wafer after acid etching and immersing it in a rinse agent, and cleaning it for 2 to 4 minutes under the flow of the rinse agent or ultrasonic vibration; wherein 10 to 20 parts by weight of a neutralizer, 2 to 5 parts by weight of alkylphenol polyoxyethylene ether and 65 to 75 parts by weight of pure water are uniformly mixed to obtain the rinse agent; (3) Taking out the cleaned single crystal silicon wafer and vacuum drying it at room temperature; (4) Adding alkaline etching liquid and the dried single crystal silicon wafer into an alkaline etching machine, and etching at a temperature of 60-70° C. for 8-10 minutes; wherein 40-50 parts by weight of alkali, 2-3 parts by weight of surfactant, 1-2 parts by weight of sodium dodecyl polyoxyethylene ether sulfate, 0.1-0.4 parts by weight of active additive and 70-80 parts by weight of pure water are mixed and stirred evenly to obtain the alkaline etching liquid; (5) After the alkali corrosion, the single crystal silicon wafer is taken out and rinsed with ultrapure water. After the rinsed single crystal silicon wafer is taken out, it is vacuum dried at room temperature to obtain a single crystal silicon wafer for the semiconductor industry that has been completely etched.

[0014] Preferably, in step (1), the acid etching solution further comprises 50-60 parts by weight of ethylene glycol.

[0015] Preferably, in step (1), the fluoride salt is selected from one or more of sodium fluoride, magnesium fluoride, and lithium fluoride.

[0016] Preferably, in step (2), the neutralizing agent is selected from one or more of triethylamine, dimethylethanolamine, diethylethanolamine, and 2-amino-2-methylpropanol.

[0017] Preferably, in step (4), the base is selected from one or more of potassium hydroxide, sodium hydroxide, ammonium hydroxide, tetramethylammonium hydroxide, tetraethylammonium hydroxide, and tetrapropylammonium hydroxide; Preferably, in step (4), the surfactant is selected from one or more of ethylene glycol, fatty alcohol polyoxyethylene ether, fatty amine polyoxyethylene ether, and lauryl alcohol polyoxyethylene ether; Preferably, in step (4), the active additive is selected from one or more of ammonium tetrafluoroborate, benzalkonium chloride, and sodium ammonium dodecyl sulfate.

[0018] Compared with the shortcomings and deficiencies of the prior art, the present invention has the following beneficial effects: the present invention adopts a corrosion method of first slowly acid etching and then fully alkali etching, which can effectively reduce the surface roughness of the silicon wafer. In addition, in the alkaline etching solution of the present invention, tetramethylammonium hydroxide is preferably used as the source of alkaline TMAH, which can fully utilize the advantages of TMAH corrosion such as environmental protection, no color spots, and low roughness. In addition, in the selection of additives for the alkaline etching solution, the present invention further reduces the surface tension of the alkali by combining surfactants, active additives, sodium dodecyl polyoxyethylene ether sulfate, etc. with alkali (including TMAH), and the corrosion rate is higher, which can not only effectively reduce the surface tension and improve the affinity of the etching solution with the silicon substrate, but also enhance the selective etching ability of silicon dioxide during the etching process, reduce the corrosion of the silicon substrate, and achieve a more uniform and precise etching effect. It has been determined that the surface roughness of the silicon wafer obtained by the etching method of the present invention is Ra≤0.1um, the single metal cation (maximum) is <1ppb, the corrosion rate can reach 1~1.5 microns / minute, and is stable within ±5%. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. Example 1

[0020] (1) Mix hydrofluoric acid, nitric acid and sodium fluoride in a mass ratio of 15:35:10 to obtain an acid etching solution; place a single crystal silicon wafer (6 inches, resistivity 0.002-0.005Ω / ㎝, TTV of the silicon wafer before etching <1, and the removal amount is required to remove 60um / double side) in the acid etching solution for acid etching, start the acid etching machine, and etch at 55°C for 3 minutes to remove the natural oxide layer of the surface pattern of the single crystal silicon wafer. The acid etching removal amount is about 20μm; (2) 10 parts by mass of triethylamine, 2 parts by mass of alkylphenol polyoxyethylene ether and 75 parts by mass of pure water are uniformly mixed to obtain a rinse agent; the single crystal silicon wafer after acid corrosion is taken out and immersed in the rinse agent, and cleaned for 2 to 4 minutes under the flow of the rinse agent or ultrasonic vibration; (3) Taking out the cleaned single crystal silicon wafer and vacuum drying it at room temperature; (4) 45 parts by mass of tetramethylammonium hydroxide, 2 parts by mass of fatty alcohol polyoxyethylene ether, 2 parts by mass of sodium dodecyl polyoxyethylene ether sulfate, 0.2 parts by mass of ammonium tetrafluoroborate and 75 parts by mass of pure water are mixed evenly to obtain an alkaline etching solution; a single crystal silicon wafer is placed in the alkaline etching solution for alkaline etching, an alkaline etching machine is started, and etching is performed at 65°C for 9 minutes, and the amount of alkaline etching removal is about 10 μm; (5) After the alkali corrosion, the single crystal silicon wafer is taken out and rinsed with ultrapure water for 30 seconds. After the rinsed single crystal silicon wafer is taken out, it is vacuum dried at room temperature to obtain the single crystal silicon wafer for the semiconductor industry that has completed corrosion and sent for inspection.

[0021] Technical effect test: 180 6-inch single crystal silicon wafers were produced by the method of this embodiment. Among them, the metal content test found that the single metal cation was <1ppb, the TTV of the single crystal silicon wafer after corrosion was <1μm, and the roughness Ra≤0.1μm was tested according to the inspection standard. 176 wafers passed the inspection, with a pass rate of 99.77%. Example 2

[0022] (1) Mix hydrofluoric acid, nitric acid and sodium fluoride in a mass ratio of 20:35:20 to obtain an acid etching solution; place a single crystal silicon wafer (6 inches, resistivity 0.002-0.005Ω / ㎝, silicon wafer TTV <1 before etching, removal amount required to remove 60um / double side) in the acid etching solution for acid etching, the acid etching temperature is 55°C, the etching time is controlled to be 3 minutes according to the etching amount requirement, start the acid etching machine, remove the natural oxide layer of the surface pattern of the single crystal silicon wafer, and the acid etching removal amount is about 20μm; (2) 20 parts by mass of dimethylethanolamine, 5 parts by mass of alkylphenol polyoxyethylene ether and 65 parts by mass of pure water are uniformly mixed to obtain a rinse agent; the single crystal silicon wafer after acid corrosion is taken out and immersed in the rinse agent, and cleaned for 2 to 4 minutes under the flow of the rinse agent or ultrasonic vibration; (3) Taking out the cleaned single crystal silicon wafer and vacuum drying it at room temperature; (4) 40 parts by mass of potassium hydroxide, 3 parts by mass of fatty amine polyoxyethylene ether, 2 parts by mass of sodium dodecyl polyoxyethylene ether sulfate, 0.4 parts by mass of benzalkonium chloride and 80 parts by mass of pure water are mixed evenly to obtain an alkaline etching solution; a single crystal silicon wafer is placed in the alkaline etching solution for alkaline etching, an alkaline etching machine is started, and the etching is performed at 70° C. for 10 minutes, and the amount of alkaline etching removed is about 10 μm; (5) After the alkali corrosion, the single crystal silicon wafer is taken out and rinsed with ultrapure water for 30 seconds. After the rinsed single crystal silicon wafer is taken out, it is vacuum dried at room temperature to obtain the single crystal silicon wafer for the semiconductor industry that has completed corrosion and sent for inspection.

[0023] Technical effect test: 180 6-inch single crystal silicon wafers were produced by the method of this embodiment. Among them, the metal content test found that the single metal cation was <120ppb, the TTV of the single crystal silicon wafer after corrosion was <1μm, and the roughness Ra≤0.1μm was tested according to the inspection standard. 178 wafers passed the inspection, with a pass rate of 98.88%. Example 3

[0024] (1) Mix hydrofluoric acid, nitric acid and lithium fluoride in a mass ratio of 10:30:15 to obtain an acid etching solution; place a single crystal silicon wafer (6 inches, resistivity 0.002-0.005Ω / ㎝, silicon wafer TTV <1 before etching, removal amount required to remove 60um / double side) in the acid etching solution for acid etching, start the acid etching machine, and etch at 55°C for 3 minutes to remove the natural oxide layer of the surface pattern of the single crystal silicon wafer. The acid etching removal amount is about 20μm; (2) 15 parts by weight of diethylethanolamine, 4 parts by weight of alkylphenol polyoxyethylene ether and 60 parts by weight of pure water are uniformly mixed to obtain a rinse agent; the single crystal silicon wafer after acid corrosion is taken out and immersed in the rinse agent, and cleaned for 2 to 4 minutes under the flow of the rinse agent or ultrasonic vibration; (3) Taking out the cleaned single crystal silicon wafer and vacuum drying it at room temperature; (4) 45 parts by mass of ammonium hydroxide, 2 parts by mass of lauryl alcohol polyoxyethylene ether, 1 part by mass of sodium dodecyl polyoxyethylene ether sulfate, 0.2 parts by mass of sodium ammonium dodecyl sulfate and 75 parts by mass of pure water are mixed evenly to obtain an alkaline etching solution; a single crystal silicon wafer is placed in the alkaline etching solution for alkaline etching, an alkaline etching machine is started, and the etching is performed at 60° C. for 8 minutes, and the amount of alkaline etching removed is about 10 μm; (5) After the alkali corrosion, the single crystal silicon wafer is taken out and rinsed with ultrapure water for 30 seconds. After the rinsed single crystal silicon wafer is taken out, it is vacuum dried at room temperature to obtain the single crystal silicon wafer for the semiconductor industry that has completed corrosion and sent for inspection.

[0025] Technical effect test: 178 6-inch single crystal silicon wafers were produced by the method of this embodiment. Among them, the metal content test found that the single metal cation was <2ppb, the TTV of the single crystal silicon wafer after corrosion was <1μm, and the roughness Ra≤0.1μm was tested according to the inspection standard. 174 wafers passed the inspection, with a pass rate of 97.75%. Example 4

[0026] (1) Mix hydrofluoric acid, nitric acid and sodium fluoride in a mass ratio of 15:35:16 to obtain an acid etching solution; place a single crystal silicon wafer (6 inches, resistivity 0.002-0.005Ω / ㎝, TTV of the silicon wafer before etching <1, and the removal amount is required to remove 60um / double side) in the acid etching solution for acid etching, start the acid etching machine, and etch at 55°C for 3 minutes to remove the natural oxide layer of the surface pattern of the single crystal silicon wafer. The acid etching removal amount is about 20μm; (2) 12 parts by mass of 2-amino-2-methylpropanol, 4 parts by mass of alkylphenol polyoxyethylene ether and 68 parts by mass of pure water are uniformly mixed to obtain a rinse agent; the single crystal silicon wafer after acid corrosion is taken out and immersed in the rinse agent, and cleaned for 2 to 4 minutes under the flow of the rinse agent or ultrasonic vibration; (3) Taking out the cleaned single crystal silicon wafer and vacuum drying it at room temperature; (4) 44 parts by mass of tetraethylammonium hydroxide, 2 parts by mass of ethylene glycol, 1 part by mass of sodium dodecyl polyoxyethylene ether sulfate, 0.3 parts by mass of ammonium tetrafluoroborate and 78 parts by mass of pure water are mixed evenly to obtain an alkaline etching solution; a single crystal silicon wafer is placed in the alkaline etching solution for alkaline etching, an alkaline etching machine is started, and the etching is carried out at 64°C for 9 minutes, and the amount of alkaline etching removed is about 10 μm; (5) After the alkali corrosion, the single crystal silicon wafer is taken out and rinsed with ultrapure water for 30 seconds. After the rinsed single crystal silicon wafer is taken out, it is vacuum dried at room temperature to obtain the single crystal silicon wafer for the semiconductor industry that has completed corrosion and sent for inspection.

[0027] Technical effect test: 183 6-inch single crystal silicon wafers were produced by the method of this embodiment. Among them, the metal content test found that the single metal cation was <1ppb, the TTV of the single crystal silicon wafer after corrosion was <1μm, and the roughness Ra≤0.1μm was tested according to the inspection standard. 181 wafers passed the inspection, and the pass rate was 98.90%. Example 5

[0028] (1) Mix hydrofluoric acid, nitric acid and sodium fluoride in a mass ratio of 15:35:10 to obtain an acid etching solution; place a single crystal silicon wafer (6 inches, resistivity 0.002-0.005Ω / ㎝, TTV of the silicon wafer before etching <1, and the removal amount is required to remove 60um / double side) in the acid etching solution for acid etching, start the acid etching machine, and etch at 55°C for 3 minutes to remove the natural oxide layer of the surface pattern of the single crystal silicon wafer. The acid etching removal amount is about 20μm; (2) 10 parts by mass of triethylamine, 5 parts by mass of alkylphenol polyoxyethylene ether and 75 parts by mass of pure water are uniformly mixed to obtain a rinse agent; the single crystal silicon wafer after acid etching is taken out and immersed in the rinse agent, and the rinse agent is flowed for 2 to 4 minutes for cleaning; (3) Taking out the cleaned single crystal silicon wafer and vacuum drying it at room temperature; (4) 44 parts by mass of tetrapropylammonium hydroxide, 2 parts by mass of lauryl alcohol polyoxyethylene ether, 2 parts by mass of sodium dodecyl polyoxyethylene ether sulfate, 0.1 parts by mass of ammonium tetrafluoroborate and 70 parts by mass of pure water are mixed evenly to obtain an alkaline etching solution; a single crystal silicon wafer is placed in the alkaline etching solution for alkaline etching, an alkaline etching machine is started, and etching is performed at 60° C. for 8 minutes, and the amount of alkaline etching removal is about 10 μm; (5) After the alkali corrosion, the single crystal silicon wafer is taken out and rinsed with ultrapure water for 30 seconds. After the rinsed single crystal silicon wafer is taken out, it is vacuum dried at room temperature to obtain the single crystal silicon wafer for the semiconductor industry that has completed corrosion and sent for inspection.

[0029] Technical effect test: 152 6-inch single crystal silicon wafers were produced by the method of this embodiment. Among them, the metal content test found that the single metal cation was <1ppb, the TTV of the single crystal silicon wafer after corrosion was <1μm, and the roughness Ra≤0.1μm was tested according to the inspection standard. 150 wafers passed the inspection, with a pass rate of 98.68%. Example 6

[0030] (1) Mix hydrofluoric acid, nitric acid and sodium fluoride in a mass ratio of 20:35:20 to obtain an acid etching solution; place a single crystal silicon wafer (6 inches, resistivity 0.002-0.005Ω / ㎝, silicon wafer TTV <1 before etching, removal amount required to remove 60um / double side) in the acid etching solution for acid etching, the acid etching temperature is 55°C, the etching time is controlled to be 3 minutes according to the etching amount requirement, start the acid etching machine, remove the natural oxide layer of the surface pattern of the single crystal silicon wafer, and the acid etching removal amount is about 20μm; (2) 18 parts by mass of dimethylethanolamine, 3 parts by mass of alkylphenol polyoxyethylene ether and 65 parts by mass of pure water are uniformly mixed to obtain a rinse agent; the single crystal silicon wafer after acid etching is taken out and immersed in the rinse agent, and cleaned under ultrasonic vibration for 2 to 4 minutes; (3) Taking out the cleaned single crystal silicon wafer and vacuum drying it at room temperature; (4) 48 parts of tetramethylammonium hydroxide, 3 parts of lauryl alcohol polyoxyethylene ether, 2 parts of sodium dodecyl polyoxyethylene ether sulfate, 0.4 parts of ammonium tetrafluoroborate and 80 parts of pure water are mixed evenly to obtain an alkaline etching solution; a single crystal silicon wafer is placed in the alkaline etching solution for alkaline etching, an alkaline etching machine is started, and the etching is performed at 70°C for 10 minutes, and the amount of alkaline etching removed is about 10 μm; (5) After the alkali corrosion, the single crystal silicon wafer is taken out and rinsed with ultrapure water for 30 seconds. After the rinsed single crystal silicon wafer is taken out, it is vacuum dried at room temperature to obtain the single crystal silicon wafer for the semiconductor industry that has completed corrosion and sent for inspection.

[0031] Technical effect test: 165 6-inch single crystal silicon wafers were produced by the method of this embodiment. Among them, the metal content test found that the single metal cation was <1ppb, the TTV of the single crystal silicon wafer after corrosion was <1μm, and the roughness Ra≤0.1μm was tested according to the inspection standard. 164 wafers passed the inspection, with a pass rate of 99.39%. Example 7

[0032] (1) Mix hydrofluoric acid, nitric acid, sodium fluoride and ethylene glycol in a mass ratio of 15:35:10:50 to obtain an acid etching solution; place a single crystal silicon wafer (6 inches, resistivity 0.002-0.005Ω / ㎝, TTV of the silicon wafer before etching <1, and the removal amount is required to remove 60um / double side) in the acid etching solution for acid etching, start the acid etching machine, and etch at 55°C for 3 minutes to remove the natural oxide layer of the surface pattern of the single crystal silicon wafer. The acid etching removal amount is about 20μm; (2) 16 parts by mass of diethylethanolamine, 4 parts by mass of alkylphenol polyoxyethylene ether and 72 parts by mass of pure water are mixed evenly to obtain a rinse agent; the single crystal silicon wafer after acid etching is taken out and immersed in the rinse agent, and cleaned under ultrasonic vibration for 3 minutes; (3) Taking out the cleaned single crystal silicon wafer and vacuum drying it at room temperature; (4) 45 parts by mass of tetramethylammonium hydroxide, 2 parts by mass of fatty alcohol polyoxyethylene ether, 2 parts by mass of sodium dodecyl polyoxyethylene ether sulfate, 0.2 parts by mass of ammonium tetrafluoroborate and 75 parts by mass of pure water are mixed evenly to obtain an alkaline etching solution; a single crystal silicon wafer is placed in the alkaline etching solution for alkaline etching, an alkaline etching machine is started, and etching is performed at 65°C for 9 minutes, and the amount of alkaline etching removal is about 10 μm; (5) After the alkali corrosion, the single crystal silicon wafer is taken out and rinsed with ultrapure water for 30 seconds. After the rinsed single crystal silicon wafer is taken out, it is vacuum dried at room temperature to obtain the single crystal silicon wafer for the semiconductor industry that has completed corrosion and sent for inspection.

[0033] Technical effect test: 182 6-inch single crystal silicon wafers were produced by the method of this embodiment. Among them, the metal content test found that the single metal cation was <1ppb, the TTV of the single crystal silicon wafer after corrosion was <1μm, and the roughness Ra≤0.1μm was tested according to the inspection standard. 181 wafers were qualified, and the qualified rate was 99.45%. Example 8

[0034] (1) Mix hydrofluoric acid, nitric acid, sodium fluoride and ethylene glycol in a mass ratio of 15:35:10:60 to obtain an acid etching solution; place a single crystal silicon wafer (6 inches, resistivity 0.002-0.005Ω / ㎝, TTV of the silicon wafer before etching <1, and the removal amount is required to remove 60um / double side) in the acid etching solution for acid etching, start the acid etching machine, and etch at 55°C for 3 minutes to remove the natural oxide layer of the surface pattern of the single crystal silicon wafer. The acid etching removal amount is about 20μm; (2) 16 parts by mass of diethylethanolamine, 4 parts by mass of alkylphenol polyoxyethylene ether and 72 parts by mass of pure water are mixed evenly to obtain a rinse agent; the single crystal silicon wafer after acid etching is taken out and immersed in the rinse agent, and cleaned under ultrasonic vibration for 3 minutes; (3) Taking out the cleaned single crystal silicon wafer and vacuum drying it at room temperature; (4) 45 parts by mass of tetramethylammonium hydroxide, 2 parts by mass of fatty alcohol polyoxyethylene ether, 2 parts by mass of sodium dodecyl polyoxyethylene ether sulfate, 0.2 parts by mass of ammonium tetrafluoroborate and 75 parts by mass of pure water are mixed evenly to obtain an alkaline etching solution; a single crystal silicon wafer is placed in the alkaline etching solution for alkaline etching, an alkaline etching machine is started, and etching is performed at 65°C for 9 minutes, and the amount of alkaline etching removal is about 10 μm; (5) After the alkali corrosion, the single crystal silicon wafer is taken out and rinsed with ultrapure water for 30 seconds. After the rinsed single crystal silicon wafer is taken out, it is vacuum dried at room temperature to obtain the single crystal silicon wafer for the semiconductor industry that has completed corrosion and sent for inspection.

[0035] Technical effect test: 183 6-inch single crystal silicon wafers were produced by the method of this embodiment. Among them, the metal content test found that the single metal cation was <1ppb, the TTV of the single crystal silicon wafer after corrosion was <1μm, and the roughness Ra≤0.1μm was tested according to the inspection standard. 182 wafers passed the inspection, and the pass rate was 99.45%.

[0036] Comparative Example 1 (1) Mix hydrofluoric acid, nitric acid and sodium fluoride in a mass ratio of 15:35:10 to obtain an acid etching solution; place a single crystal silicon wafer (6 inches, resistivity 0.002-0.005Ω / ㎝, TTV of the silicon wafer before etching <1, and the removal amount is required to remove 60um / double side) in the acid etching solution for acid etching, start the acid etching machine, and etch at 55°C for 3 minutes to remove the natural oxide layer of the surface pattern of the single crystal silicon wafer. The acid etching removal amount is about 20μm; (2) 10 parts by mass of triethylamine, 2 parts by mass of alkylphenol polyoxyethylene ether and 75 parts by mass of pure water are uniformly mixed to obtain a rinse agent; the single crystal silicon wafer after acid corrosion is taken out and immersed in the rinse agent, and cleaned for 2 to 4 minutes under the flow of the rinse agent or ultrasonic vibration; (3) Taking out the cleaned single crystal silicon wafer and vacuum drying it at room temperature; (4) 45 parts by mass of tetramethylammonium hydroxide, 2 parts by mass of fatty alcohol polyoxyethylene ether and 75 parts by mass of pure water are mixed evenly to obtain an alkaline etching solution; a single crystal silicon wafer is placed in the alkaline etching solution for alkaline etching, an alkaline etching machine is started, and the etching is performed at 65°C for 30 minutes, and the amount of alkaline etching removed is about 10 μm; (5) After the alkali corrosion, the single crystal silicon wafer is taken out and rinsed with ultrapure water for 30 seconds. After the rinsed single crystal silicon wafer is taken out, it is vacuum dried at room temperature to obtain the single crystal silicon wafer for the semiconductor industry that has completed corrosion and sent for inspection.

[0037] Technical effect test: 180 6-inch single crystal silicon wafers were produced by the method of this embodiment. Among them, the metal content test found that the single metal cation was <1ppb, the TTV of the single crystal silicon wafer after corrosion was greater than 3μm, and the roughness Ra≤0.1μm was tested according to the inspection standard. 85 wafers were qualified, and the qualified rate was 47.22%.

[0038] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. An alkaline etching solution for silicon used in the semiconductor industry, characterized in that: The alkaline etching solution comprises the following components in parts by mass: 40-50 parts of alkali, 2-3 parts of surfactant, 1-2 parts of sodium dodecyl polyoxyethylene ether sulfate, 0.1-0.4 parts of active additive and 70-80 parts of pure water.

2. The alkaline etching solution according to claim 1, characterized in that The base is selected from one or more of potassium hydroxide, sodium hydroxide, ammonium hydroxide, tetramethylammonium hydroxide, tetraethylammonium hydroxide, and tetrapropylammonium hydroxide.

3. The alkaline etching solution according to claim 2, characterized in that The base is tetramethylammonium hydroxide.

4. The alkaline etching solution according to claim 1, characterized in that The surfactant is selected from one or more of ethylene glycol, fatty alcohol polyoxyethylene ether, fatty amine polyoxyethylene ether, and lauryl alcohol polyoxyethylene ether.

5. The alkaline etching solution according to claim 1, characterized in that The active additive is selected from one or more of ammonium tetrafluoroborate, benzalkonium chloride, and sodium ammonium dodecyl sulfate.

6. A method for etching silicon for use in the semiconductor industry, characterized in that: The method comprises the following steps: (1) adding an acid etching solution and a single crystal silicon wafer into an acid etching machine, and performing root etching at a temperature of 45 to 75° C. for 2 to 6 minutes to remove the natural oxide layer of the surface pattern of the single crystal silicon wafer; wherein 10 to 20 parts by weight of hydrofluoric acid, 30 to 35 parts by weight of nitric acid, and 10 to 20 parts by weight of a fluoride salt are mixed and stirred uniformly to obtain the acid etching solution; (2) taking out the single crystal silicon wafer after acid etching and immersing it in a rinse agent, and cleaning it for 2 to 4 minutes under the flow of the rinse agent or ultrasonic vibration; wherein 10 to 20 parts by weight of a neutralizer, 2 to 5 parts by weight of alkylphenol polyoxyethylene ether and 65 to 75 parts by weight of pure water are uniformly mixed to obtain the rinse agent; (3) Taking out the cleaned single crystal silicon wafer and vacuum drying it at room temperature; (4) Adding alkaline etching liquid and the dried single crystal silicon wafer into an alkaline etching machine, and etching at a temperature of 60-70° C. for 8-10 minutes; wherein 40-50 parts by weight of alkali, 2-3 parts by weight of surfactant, 1-2 parts by weight of sodium dodecyl polyoxyethylene ether sulfate, 0.1-0.4 parts by weight of active additive and 70-80 parts by weight of pure water are mixed and stirred evenly to obtain the alkaline etching liquid; (5) After the alkali corrosion, the single crystal silicon wafer is taken out and rinsed with ultrapure water. After the rinsed single crystal silicon wafer is taken out, it is vacuum dried at room temperature to obtain a single crystal silicon wafer for the semiconductor industry that has been completely etched.

7. The etching method according to claim 6, characterized in that: In step (1), the acid etching solution also includes 50-60 parts by weight of ethylene glycol.

8. The etching method according to claim 6, characterized in that: In step (1), the fluoride salt is selected from one or more of sodium fluoride, magnesium fluoride, and lithium fluoride.

9. The etching method according to claim 6, characterized in that: In step (2), the neutralizing agent is selected from one or more of triethylamine, dimethylethanolamine, diethylethanolamine, and 2-amino-2-methylpropanol.

10. The etching method according to claim 6, characterized in that: In step (4), the base is selected from one or more of potassium hydroxide, sodium hydroxide, ammonium hydroxide, tetramethylammonium hydroxide, tetraethylammonium hydroxide, and tetrapropylammonium hydroxide; The surfactant is selected from one or more of ethylene glycol, fatty alcohol polyoxyethylene ether, fatty amine polyoxyethylene ether, and lauryl alcohol polyoxyethylene ether; The active additive is selected from one or more of ammonium tetrafluoroborate, benzalkonium chloride, and sodium ammonium dodecyl sulfate.