Annealing process of monocrystalline silicon wafer

Abstract

The invention provides an annealing process of a monocrystalline silicon wafer. The annealing process comprises the following steps: cleaning a silicon wafer before annealing; annealing and cleaning the furnace tube; putting the silicon wafer into the furnace tube for annealing; and cleaning the silicon wafer after annealing. The method has the beneficial effects that by carrying out annealing cleaning on the furnace tube before the silicon wafer is annealed and adjusting the cleaning process of the silicon wafer after high-temperature annealing, the aggregation of small particles in the edge area of the silicon wafer after high-temperature annealing is reduced, the annealing quality and the surface cleanliness of the silicon wafer are improved, and the use performance of the silicon wafer is ensured.

Description

Technical Field

[0001] The present invention belongs to the field of semiconductor technology, and particularly relates to an annealing process for single crystal silicon wafers. Background Art

[0002] Semiconductor single crystal pulling is mainly divided into two categories: Czochralski method and zone melting method. For Czochralski single crystals, because quartz crucibles are used, the oxygen content in the crystal is higher than that of zone melting single crystals. The mechanical properties of silicon wafers are better than those of zone melting single crystals, and the application fields are much wider than those of zone melting single crystals. During use, devices have high requirements for defect-free and internal gettering of Czochralski single crystal silicon wafers. During the process of growing single crystals by the Czochralski method, due to the aggregation of vacancies, a kind of cavity-type microdefect will be formed, that is, crystal originated particles (COP). This kind of defect will reduce the integrity of the device gate oxide layer. In order to meet the requirements of device preparation, it is necessary to reduce the crystal originated particles (COP) on the surface of the silicon wafer. The argon annealing process can solve the COP on the surface layer of the silicon wafer and form a denuded zone (DZ) layer and bulk microdefects (BMD) layer inside the silicon wafer, meeting the requirements of the device for internal gettering.

[0003] In the prior art, after high-temperature argon annealing of single crystal silicon wafers, particle testing and particle morphology analysis are respectively carried out using a particle tester and a particle morphology tester. Circular small particles with a size of 30 - 50 nm will be formed on the surface of the single crystal silicon wafer, especially in the edge area. The main components are C, O, and Si, as Figure 1 and Figure 2 shown, and it is difficult to remove these small particles using conventional post-annealing cleaning processes, which affects the electrical properties of the silicon wafer. Summary of the Invention

[0004] In order to solve the above technical problems, the present invention provides an annealing process for single crystal silicon wafers, effectively solving the technical problem that small particles are generated on the surface edge of the silicon wafer after high-temperature annealing and are difficult to remove, and overcoming the deficiencies of the prior art.

[0005] The technical solution adopted by the present invention is: an annealing process for single crystal silicon wafers, including the following steps:

[0006] Performing pre-annealing cleaning on the silicon wafer;

[0007] Performing annealing cleaning on the furnace tube;

[0008] Placing the silicon wafer into the furnace tube for annealing;

[0009] Performing post-annealing cleaning on the silicon wafer.

[0010] Further, in the step of performing annealing cleaning on the furnace tube, it includes:

[0011] The first heating process, introducing nitrogen into the furnace tube and raising the temperature of the furnace tube to the furnace tube annealing temperature;

[0012] The first annealing process: Oxygen and a chlorine-containing atmosphere are introduced into the furnace tube, and the temperature of the furnace tube is maintained at the furnace tube annealing temperature without change.

[0013] The first cooling process: Nitrogen is introduced into the furnace tube to cool down the furnace tube.

[0014] Furthermore, during the first annealing process, the furnace tube annealing temperature is set to 1150 - 1250 °C, and the annealing time is set to 1 - 10 h.

[0015] Furthermore, the flow rate of the nitrogen is set to 5 - 20 SLM, the flow rate of the oxygen is set to 5 - 20 SLM, and the flow rate of the chlorine-containing atmosphere is set to 0.1 - 5 SLM.

[0016] Furthermore, the chlorine-containing atmosphere is set to hydrogen chloride or dichloroethylene.

[0017] Furthermore, the step of putting the silicon wafer into the furnace tube for annealing includes:

[0018] The second heating process: Argon is introduced into the furnace tube, and the furnace tube is heated to the silicon wafer annealing temperature at a continuously decreasing heating rate.

[0019] The second annealing process: Argon is introduced into the furnace tube, and the temperature of the furnace tube is maintained at the silicon wafer annealing temperature without change.

[0020] The second cooling process: Argon is introduced into the furnace tube, and the furnace tube is cooled at a continuously increasing cooling rate.

[0021] Furthermore, during the second annealing process, the silicon wafer annealing temperature is set to 1150 - 1250 °C, the annealing time is set to 1 - 10 h, and the flow rate of the argon is set to 5 - 20 SLM.

[0022] Furthermore, the step of cleaning the silicon wafer after annealing includes cleaning the silicon wafer with a mixed solution composed of ammonia water, hydrogen peroxide, and deionized water.

[0023] Furthermore, the volume ratio of the mixed solution is set to NH3·H2O:H2O2:DIW = 1:(1 - 3):1000.

[0024] Furthermore, the cleaning time of the mixed solution is set to 10 - 30 s.

[0025] The advantages and positive effects of the present invention are: By annealing and cleaning the furnace tube before annealing the silicon wafer and adjusting the cleaning process of the silicon wafer after high-temperature annealing, the aggregation of small particles in the edge region of the silicon wafer after high-temperature annealing is reduced, the annealing quality and surface cleanliness of the silicon wafer are improved, and the service performance of the silicon wafer is ensured. Brief Description of the Drawings

[0026] Figure 1 is a schematic diagram of particle testing after annealing of a silicon wafer in the prior art.

[0027] Figure 2 is a schematic diagram of particle morphology analysis after annealing of a silicon wafer in the prior art.

[0028] Figure 3 is a process flow chart of an annealing process for a single crystal silicon wafer according to an embodiment of the present invention.

[0029] Figure 4 is a schematic diagram of particle testing of an annealing process for a single crystal silicon wafer according to Embodiment 1 of the present invention.

[0030] Figure 5 is a schematic diagram of particle testing of an annealing process for a single crystal silicon wafer according to Embodiment 2 of the present invention. Detailed Embodiments

[0031] The embodiments of the present invention provide an annealing process for a single crystal silicon wafer. The embodiments of the present invention will be described below with reference to the accompanying drawings.

[0032] In the description of the embodiments of the present invention, it should be understood that the orientation or positional relationship indicated by terms such as "top", "bottom", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. In the description of the present invention, it should be noted that unless otherwise clearly defined and limited, the terms "set" and "connect" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be directly connected, or indirectly connected through an intermediate medium, and may be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0033] As Figure 3 shown, the present invention provides an annealing process for a single crystal silicon wafer, including the following steps: cleaning the silicon wafer before annealing; annealing and cleaning the furnace tube; placing the silicon wafer in the furnace tube for annealing; cleaning the silicon wafer after annealing. Before annealing the silicon wafer, the furnace tube is annealed first to clean the inside of the furnace tube, reducing the influence of metal impurities on the silicon wafer. Cleaning the silicon wafer before and after annealing further ensures the cleanliness of the silicon wafer.

[0034] The following is a detailed introduction:

[0035] S1: Cleaning the silicon wafer before annealing;

[0036] Before silicon wafer polishing, control the X-axis crystal orientation deviation to be 0.25 ± 0.1°, and minimize the introduction of other types of particles. Place the polished silicon wafers into an O3 tank, an HF tank, an O3 tank, an SC1-1 tank, and an SC1-2 tank in sequence for wet cleaning, and dry them in a drying tank to remove organic substances, particles, and metal residues on the silicon wafer surface.

[0037] S2: Anneal and clean the furnace tube;

[0038] Before annealing the silicon wafer, first anneal and clean the furnace tube to remove metal impurities inside the furnace tube. It includes the following steps:

[0039] a. Start the annealing furnace;

[0040] Introduce nitrogen into the furnace tube, set the flow rate to 5 - 20 SLM, and heat the furnace tube to 550 - 650 °C.

[0041] b. The first heating process;

[0042] Introduce nitrogen into the furnace tube, set the flow rate to 5 - 20 SLM, raise the temperature of the furnace tube to the furnace tube annealing temperature, set the heating rate to 1 - 15 °C / s, and set the furnace tube annealing temperature to 1150 - 1250 °C.

[0043] c. The first annealing process;

[0044] Introduce oxygen and a chlorine-containing atmosphere into the furnace tube, keep the temperature of the furnace tube unchanged at the furnace tube annealing temperature, and set the annealing time to 1 - 10 h. The chlorine-containing atmosphere is set to hydrogen chloride or dichloroethylene.

[0045] In a high-temperature environment, the chlorine-containing atmosphere reacts with the oxygen entering the furnace tube simultaneously. The generated chlorine atoms have very strong reaction activities and will react with trace metal ions on the furnace tube wall to form stable chloro-metal salts, thereby fixing the metal ions on the tube wall and preventing the metal ions from ionizing in subsequent processes. When a certain amount of chloro-metal salts is generated, they will be carried out of the furnace tube by the gas flow from the tail gas pipe due to their small particle size. During the annealing and cleaning process, if the oxygen supply is insufficient, a small amount of phosgene will be generated. Phosgene decomposes rapidly into carbon dioxide and hydrogen chloride when it meets water. Insufficient oxygen supply will also cause carbon deposition in the tail gas pipeline. Therefore, the flow rate of oxygen is greater than that of the chlorine-containing atmosphere. Preferably, the flow rate of oxygen is set to 5 - 20 SLM, the flow rate of the chlorine-containing atmosphere is set to 0.1 - 5 SLM, and the concentration of the chlorine-containing atmosphere is set to 35% - 38%.

[0046] d. The first cooling process;

[0047] Introduce nitrogen into the furnace tube, set the flow rate to 5 - 20 SLM, and lower the temperature of the furnace tube to 550 - 650 °C.

[0048] S3. Place the silicon wafer into the furnace tube for annealing;

[0049] a. Loading the silicon wafer into the furnace;

[0050] Place the silicon wafer into the furnace tube, introduce argon gas into the furnace tube, set the flow rate to 5 - 20 SLM, and raise the temperature of the furnace tube to 550 - 650 °C.

[0051] b. The second heating process;

[0052] Introduce argon gas into the furnace tube, set the flow rate to 5 - 20 SLM, and heat the furnace tube to the silicon wafer annealing temperature at a continuously decreasing heating rate. The silicon wafer annealing temperature is set to 1150 - 1250 °C. During the heating process below 950 °C, control the heating rate at 1 - 10 °C / min; during the heating process from 950 - 1000 °C, control the heating rate at 1 - 5 °C / min; during the heating process from 1000 - 1150 °C, control the heating rate at 1 - 3 °C / min; and during the heating process above 1150 °C, control the heating rate to be less than 2 °C / min. The decreasing heating rate can minimize the slip line defects of the silicon wafer.

[0053] c. The second annealing process;

[0054] Introduce argon gas into the furnace tube, set the flow rate to 5 - 20 SLM, keep the temperature of the furnace tube at the silicon wafer annealing temperature unchanged, and set the annealing time to 1 - 10 h.

[0055] d. The second cooling process;

[0056] Introduce argon gas into the furnace tube, set the flow rate to 5 - 20 SLM, and cool the furnace tube to 550 - 650 °C at a continuously increasing cooling rate. During the cooling process above 1150 °C, control the cooling rate to be less than 2 °C / min; during the cooling process from 1150 - 1000 °C, control the cooling rate at 1 - 3 °C / min; during the cooling process from 1000 - 950 °C, control the cooling rate at 1 - 5 °C / min; and during the cooling process below 950 °C, control the cooling rate at 1 - 10 °C / min. The increasing cooling rate can minimize the slip line defects of the silicon wafer.

[0057] S4. Clean the silicon wafer after annealing;

[0058] During the post-annealing cleaning process, a mixed solution composed of ammonia water, hydrogen peroxide, and deionized water is first used to clean the silicon wafers. The mixed solution is placed in a single-wafer cleaning machine to perform single-wafer cleaning on the silicon wafers, achieving high cleanliness, high uniformity, and no cross-contamination. By oxidation and micro-etching, particles on the surface of the silicon wafers are removed, and mild organic contamination and partial metal contamination can also be removed. The volume ratio of the mixed solution is set as NH3·H2O:H2O2:DIW = 1:(1 - 3):1000. The cleaning time of the mixed solution is set as 10 - 30 s.

[0059] After cleaning with the mixed solution, O3, HF, and DIW are used for multiple cycles of cleaning and then drying.

[0060] Example 1: An annealing process for single-crystalline silicon wafers includes the following steps:

[0061] S1: Perform pre-annealing cleaning on the silicon wafers;

[0062] Before the silicon wafers are polished, control the X-axis crystal orientation deviation to be 0.25 ± 0.1°, and try to reduce the introduction of other types of particles. The polished silicon wafers are sequentially placed in an O3 tank, an HF tank, an O3 tank, an SC1-1 tank, and an SC1-2 tank for wet cleaning, and then dried in a drying tank.

[0063] S2: Perform annealing cleaning on the furnace tube;

[0064] Before annealing the silicon wafers, first perform annealing cleaning on the furnace tube to remove metal impurities inside the furnace tube. It includes the following steps:

[0065] a. Start the annealing furnace;

[0066] Introduce nitrogen into the furnace tube, set the flow rate to 5 SLM, and heat the furnace tube to 550 °C.

[0067] b. The first heating process;

[0068] Introduce nitrogen into the furnace tube, set the flow rate to 5 SLM, raise the temperature of the furnace tube to the furnace tube annealing temperature, set the heating rate to 1 °C / s, and the furnace tube annealing temperature is set to 1150 °C.

[0069] c. The first annealing process;

[0070] Introduce oxygen and a chlorine-containing atmosphere into the furnace tube, keep the temperature of the furnace tube unchanged at the furnace tube annealing temperature, and set the annealing time to 1 h. The chlorine-containing atmosphere is set as hydrogen chloride. The concentration of hydrogen chloride is set to 35%. The flow rate of oxygen is set to 5 SLM, and the flow rate of hydrogen chloride is set to 0.1 SLM.

[0071] d. The first cooling process;

[0072] Introduce nitrogen into the furnace tube, set the flow rate to 5 SLM, and reduce the temperature of the furnace tube to 550 °C.

[0073] S3. Place the silicon wafer into the furnace tube for annealing;

[0074] a. The silicon wafer enters the furnace;

[0075] Place the silicon wafer into the furnace tube, introduce argon into the furnace tube, set the flow rate to 5 SLM, and raise the temperature of the furnace tube to 550 °C.

[0076] b. The second heating process;

[0077] Introduce argon into the furnace tube, set the flow rate to 5 SLM, and raise the temperature of the furnace tube to the annealing temperature of the silicon wafer at a continuously decreasing heating rate. The annealing temperature of the silicon wafer is set to 1150 °C. During the heating process below 950 °C, the heating rate is 5 °C / min. During the heating process from 950 to 1000 °C, the heating rate is 2.5 °C / min. During the heating process from 1000 to 1150 °C, the heating rate is 2 °C / min.

[0078] c. The second annealing process;

[0079] Introduce argon into the furnace tube, set the flow rate to 5 SLM, keep the temperature of the furnace tube constant at the annealing temperature of the silicon wafer, and set the annealing time to 1 h.

[0080] d. The second cooling process;

[0081] Introduce argon into the furnace tube, set the flow rate to 5 SLM, and cool the furnace tube to 550 °C at a continuously increasing cooling rate. During the cooling process from 1150 to 1000 °C, the cooling rate is 2 °C / min. During the cooling process from 1000 to 950 °C, the cooling rate is 3 °C / min. During the cooling process below 950 °C, the cooling rate is 5 °C / min.

[0082] S4. Clean the silicon wafer after annealing;

[0083] During the post-annealing cleaning process, first clean the silicon wafer with a mixed solution composed of ammonia water, hydrogen peroxide, and deionized water. Place this mixed solution in a single-wafer cleaning machine and perform single-wafer cleaning on the silicon wafer. The volume ratio of the mixed solution is set to NH3·H2O:H2O2:DIW = 1:1:1000. The cleaning time of the mixed solution is set to 10 s.

[0084] After cleaning with the mixed solution, perform multiple cycles of cleaning with O3, HF, and DIW, and then dry.

[0085] Example 2: An annealing process for a single-crystal silicon wafer, comprising the following steps:

[0086] S1: Perform pre-annealing cleaning on the silicon wafer;

[0087] Before silicon wafer polishing, control the X-axis crystal orientation deviation to be 0.25 ± 0.1°, and minimize the introduction of other types of particles. Place the polished silicon wafer into the O3 tank, HF tank, O3 tank, SC1-1 tank, and SC1-2 tank in sequence for wet cleaning, and dry it in the drying tank.

[0088] S2: Perform annealing cleaning on the furnace tube;

[0089] Before annealing the silicon wafer, first perform annealing cleaning on the furnace tube to remove the metal impurities inside the furnace tube. It includes the following steps:

[0090] a. Start the annealing furnace;

[0091] Inject nitrogen into the furnace tube, set the flow rate to 20 SLM, and heat the furnace tube to 650°C.

[0092] b. The first heating process;

[0093] Inject nitrogen into the furnace tube, set the flow rate to 20 SLM, raise the temperature of the furnace tube to the furnace tube annealing temperature, set the heating rate to 15°C / s, and set the furnace tube annealing temperature to 1250°C.

[0094] c. The first annealing process;

[0095] Inject oxygen and a chlorine-containing atmosphere into the furnace tube, keep the temperature of the furnace tube unchanged at the furnace tube annealing temperature, set the annealing time to 10 h. Set the chlorine-containing atmosphere to dichloroethylene. Set the concentration of dichloroethylene to 38%. Set the flow rate of oxygen to 20 SLM, and set the flow rate of dichloroethylene to 5 SLM.

[0096] d. The first cooling process;

[0097] Inject nitrogen into the furnace tube, set the flow rate to 20 SLM, and lower the temperature of the furnace tube to 650°C.

[0098] S3. Place the silicon wafer into the furnace tube for annealing;

[0099] a. The silicon wafer enters the furnace;

[0100] Place the silicon wafer into the furnace tube, inject argon into the furnace tube, set the flow rate to 20 SLM, and raise the temperature of the furnace tube to 650°C.

[0101] b. The second heating process;

[0102] Argon is introduced into the furnace tube with a flow rate set at 20 SLM. The furnace tube is heated to the silicon wafer annealing temperature at a continuously decreasing heating rate. The silicon wafer annealing temperature is set at 1250 °C. During the heating process below 950 °C, the heating rate is 5 °C / min; during the heating process from 950 to 1000 °C, the heating rate is 2.5 °C / min; during the heating process from 1000 to 1150 °C, the heating rate is 2 °C / min; and during the heating process above 1150 °C, the heating rate is 1 °C / min.

[0103] c. The second annealing process;

[0104] Argon is introduced into the furnace tube with a flow rate set at 20 SLM. The temperature of the furnace tube is kept constant at the silicon wafer annealing temperature, and the annealing time is set at 10 h.

[0105] d. The second cooling process;

[0106] Argon is introduced into the furnace tube with a flow rate set at 20 SLM. The furnace tube is cooled to 650 °C at a continuously increasing cooling rate. During the cooling process above 1150 °C, the cooling rate is 1 °C / min; during the cooling process from 1150 to 1000 °C, the cooling rate is 2 °C / min; during the cooling process from 1000 to 950 °C, the cooling rate is 3 °C / min; and during the cooling process below 950 °C, the cooling rate is controlled at 5 °C / min.

[0107] S4. Clean the silicon wafer after annealing;

[0108] During the post-annealing cleaning process, first, the silicon wafer is cleaned with a mixed solution composed of ammonia water, hydrogen peroxide, and deionized water. The mixed solution is placed in a single-wafer cleaning machine to perform single-wafer cleaning on the silicon wafer. The volume ratio of the mixed solution is set as NH3·H2O:H2O2:DIW = 1:3:1000. The cleaning time of the mixed solution is set at 10 s.

[0109] After cleaning with the mixed solution, it is then cleaned cyclically multiple times with O3, HF, and DIW and dried.

[0110] Comparative example: An annealing process for a single-crystalline silicon wafer. In this embodiment, the furnace tube is not annealed and cleaned before the silicon wafer annealing, and the silicon wafer is not cleaned with a mixed solution composed of ammonia water, hydrogen peroxide, and deionized water after the silicon wafer annealing, including the following steps:

[0111] S1: Clean the silicon wafer before annealing;

[0112] Before silicon wafer polishing, control the deviation of the X-axis crystal orientation to be 0.25 ± 0.1°, and minimize the introduction of other types of particles. Put the polished silicon wafer into an O3 tank, an HF tank, an O3 tank, an SC1-1 tank, and an SC1-2 tank in sequence for wet cleaning, and dry it in a drying tank.

[0113] S2. Put the silicon wafer into a furnace tube for annealing;

[0114] a. Put the silicon wafer into the furnace;

[0115] Put the silicon wafer into the furnace tube, introduce argon into the furnace tube, set the flow rate to 20 SLM, and raise the temperature of the furnace tube to 650 °C.

[0116] b. The second heating process;

[0117] Introduce argon into the furnace tube, set the flow rate to 20 SLM, and raise the temperature of the furnace tube to the silicon wafer annealing temperature at a continuously decreasing heating rate. The silicon wafer annealing temperature is set to 1250 °C. During the heating process below 950 °C, the heating rate is 5 °C / min. During the heating process from 950 to 1000 °C, the heating rate is 2.5 °C / min. During the heating process from 1000 to 1150 °C, the heating rate is 2 °C / min. During the heating process above 1150 °C, the heating rate is 1 °C / min.

[0118] c. The second annealing process;

[0119] Introduce argon into the furnace tube, set the flow rate to 20 SLM, and keep the temperature of the furnace tube at the silicon wafer annealing temperature unchanged. Set the annealing time to 10 h.

[0120] d. The second cooling process;

[0121] Introduce argon into the furnace tube, set the flow rate to 20 SLM, and cool the furnace tube to 650 °C at a continuously increasing cooling rate. During the cooling process above 1150 °C, the cooling rate is 1 °C / min. During the cooling process from 1150 to 1000 °C, the cooling rate is 2 °C / min. During the cooling process from 1000 to 950 °C, the cooling rate is 3 °C / min. During the cooling process below 950 °C, control the cooling rate to be 5 °C / min.

[0122] S3. Clean the silicon wafer after annealing;

[0123] Put the silicon wafer into a single-wafer cleaning machine and perform multiple cycle cleaning with O3, HF, and DIW, and then dry it.

[0124] Put the silicon wafers processed in Example 1, Example 2, and the comparative example into a particle tester respectively to perform silicon wafer surface particle testing. Figure 4 and Figure 5 are the test results of Example 1 and Example 2.Figure 1 As the test results of the comparative example, it can be clearly seen that the small particles in the edge regions of the silicon wafers in the first embodiment and the second embodiment are significantly reduced.

[0125] Advantages and positive effects of the present invention:

[0126] By annealing and cleaning the furnace tube before annealing the silicon wafer and adjusting the cleaning process of the silicon wafer after high-temperature annealing, the aggregation of small particles in the edge region of the silicon wafer after high-temperature annealing is reduced, the annealing quality and surface cleanliness of the silicon wafer are improved, and the service performance of the silicon wafer is ensured.

[0127] The embodiments of the present invention have been described in detail above, but the above content is only the preferred embodiments of the present invention and cannot be considered as limiting the scope of implementation of the present invention. Any equivalent changes and improvements made according to the scope of the application of the present invention should still fall within the scope covered by the patent of the present invention.

Claims

1. An annealing process for single-crystal silicon wafers, characterized in that, It includes the following steps: Clean the silicon wafer before annealing; Clean the furnace tube for annealing; Put the silicon wafer into the furnace tube for annealing; Clean the silicon wafer after annealing.

2. The annealing process of a single crystal silicon wafer according to claim 1, characterized in that, In the step of cleaning the furnace tube for annealing, it includes: The first heating process, introducing nitrogen into the furnace tube and heating the temperature of the furnace tube to the furnace tube annealing temperature; The first annealing process, introducing oxygen and a chlorine-containing atmosphere into the furnace tube, and keeping the temperature of the furnace tube unchanged at the furnace tube annealing temperature; The first cooling process, introducing nitrogen into the furnace tube and cooling the furnace tube.

3. The annealing process of a single-crystalline silicon wafer according to claim 2, characterized in that: In the first annealing process, the furnace tube annealing temperature is set to 1150 - 1250 °C, and the annealing time is set to 1 - 10 h.

4. The annealing process of a single-crystalline silicon wafer according to claim 2 or 3, characterized in that: The flow rate of the nitrogen is set to 5 - 20 SLM, the flow rate of the oxygen is set to 5 - 20 SLM, and the flow rate of the chlorine-containing atmosphere is set to 0.1 - 5 SLM.

5. The annealing process of a single crystal silicon wafer according to claim 4, characterized in that: The chlorine-containing atmosphere is set to hydrogen chloride or dichloroethylene.

6. A annealing process for single crystal silicon wafers according to claims 1-3, characterized in that, In the step of putting the silicon wafer into the furnace tube for annealing, it includes: The second heating process, introducing argon into the furnace tube, and heating the furnace tube to the silicon wafer annealing temperature at a continuously decreasing heating rate; The second annealing process, introducing argon into the furnace tube, and keeping the temperature of the furnace tube unchanged at the silicon wafer annealing temperature; The second cooling process, introducing argon into the furnace tube, and cooling the furnace tube at a continuously increasing cooling rate.

7. The annealing process of a single crystal silicon wafer according to claim 6, characterized in that: In the second annealing process, the silicon wafer annealing temperature is set to 1150 - 1250 °C, the annealing time is set to 1 - 10 h, and the flow rate of the argon is set to 5 - 20 SLM.

8. An annealing process for a single crystal silicon wafer according to any one of claims 1-3, 5, and 7, characterized in that: In the step of cleaning the silicon wafer after annealing, it includes cleaning the silicon wafer with a mixed solution composed of ammonia water, hydrogen peroxide and deionized water.

9. The annealing process of a single crystal silicon wafer according to claim 6, characterized in that: The volume ratio of the mixed solution is set to NH3·H2O:H2O2:DIW = 1:(1 - 3):1000.

10. A annealing process for single crystal silicon wafers according to claim 6, characterized in that: The cleaning time of the mixed solution is set to 10 - 30 s.

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