Preparation method of bamboo-based active carbon source for synthesizing semiconductor-grade silicon carbide grains

Abstract

This invention relates to the field of bamboo-based activated carbon source technology, specifically to a method for preparing a bamboo-based activated carbon source for semiconductor-grade silicon carbide grain synthesis, comprising the following steps: S1: Raw material screening and pretreatment, selecting healthy moso bamboo, cutting the middle part of the bamboo material, crushing it to obtain bamboo powder; soaking the bamboo powder in deionized water; then placing the soaked bamboo powder in a vacuum freeze-drying oven to obtain dried bamboo powder; S2: Impurity removal treatment; removing impurities from the dried bamboo powder in S1 to obtain impurity-removed bamboo powder; S3: Carbonization treatment: placing the impurity-removed bamboo powder in a sealed, oxygen-free calcining furnace, introducing inert gas as a protective gas, calcining, and then cooling to room temperature under an inert atmosphere to obtain bamboo charcoal. This carbon source has rich pores, and in terms of carbonization, pre-oxidation, and purification processes, it has progressive significance compared to natural flake graphite carbon sources and relatively dense artificial carbon sources such as petroleum coke and pitch coke, in the process of semiconductor-grade silicon carbide grain synthesis.

Description

Technical Field

[0001] This invention relates to the field of bamboo-based activated carbon source technology, specifically to a method for preparing a bamboo-based activated carbon source for semiconductor-grade silicon carbide grain synthesis. Background Technology

[0002] Currently, the high-purity carbon source for synthesizing semiconductor-grade silicon carbide grains is mainly flake-shaped natural graphite. The main advantage of natural graphite is its natural layered structure, which facilitates the penetration of high-purity silicon liquid. This accelerates the synthesis reaction and allows for more complete reaction processes. However, natural graphite, derived from mineral veins, contains a relatively high amount of impurities, requiring multiple purification processes to meet the purity standard (6N) for semiconductor-grade silicon carbide grain synthesis. Artificial carbon sources include petroleum coke, pitch coke, and biomass coke.

[0003] However, existing bamboo-based activated carbon preparation technologies are mostly aimed at general industrial applications. The purity of the products (especially the content of metal impurities) and the precision of pore structure control are insufficient. When used directly as a carbon source for the synthesis of semiconductor-grade silicon carbide grains, there are still problems such as excessive impurities and unstable reaction activity, which cannot meet the stringent requirements of semiconductor-grade raw materials. At the same time, the uneven distribution of pore structure cannot provide a stable mass transfer and reaction interface for the silicon carbide synthesis reaction. Summary of the Invention

[0004] In view of the above-mentioned shortcomings of the prior art, the present invention provides a method for preparing a bamboo-based active carbon source for semiconductor-grade silicon carbide grain synthesis, which can effectively solve the problems in the prior art.

[0005] This invention provides a method for preparing a bamboo-based activated carbon source for the synthesis of semiconductor-grade silicon carbide grains, comprising the following steps:

[0006] S1: Raw material screening and pretreatment: Select healthy moso bamboo, cut the bamboo material from the middle part, crush it to obtain bamboo powder; soak the bamboo powder in deionized water; then place the soaked bamboo powder in a vacuum freeze-drying oven to obtain dried bamboo powder.

[0007] S2: Impurity removal treatment; removing impurities from the dried bamboo powder in S1 to obtain impurity-removed bamboo powder;

[0008] S3: Carbonization treatment: Place the cleaned bamboo powder in a sealed, oxygen-free calcining furnace, introduce inert gas as a protective gas, calcine, and then cool to room temperature under the protection of an inert atmosphere to obtain bamboo charcoal.

[0009] S4: Grinding process: The bamboo charcoal obtained by carbonization is ground into powder using a Raymond mill to obtain bamboo charcoal powder.

[0010] S5: Pre-oxidation treatment: The bamboo charcoal powder obtained by grinding is mixed with the oxidant according to the solid-liquid ratio, placed in a calcining furnace, and inert gas is introduced as a protective gas for calcination to complete the pre-oxidation treatment and obtain pre-oxidized bamboo charcoal powder.

[0011] S6: Place the pre-oxidized bamboo charcoal powder in an atmosphere tube furnace, switch the protective gas, and introduce a mixed activation gas of high-purity water vapor and high-purity carbon dioxide. After activation, continue to introduce inert gas to cool to room temperature to obtain crude bamboo-based activated carbon.

[0012] S7: The crude bamboo-based activated carbon is loaded into a graphite jar, then into a purification furnace. Ar gas is introduced as a protective gas, and a special organic gas containing halogen elements is introduced for 10-20 hours. After the organic gas decomposes at high temperature, the halogen elements react with the impurities in the bamboo charcoal to form gaseous metal halides, which are discharged from the purification furnace system through a vacuum system to achieve 6N-level purification of the bamboo charcoal carbon source. After purification, Ar gas is continued to be introduced to cool to room temperature to obtain refined bamboo-based activated carbon.

[0013] S8: Crushing and Grading: The refined bamboo-based activated carbon is crushed to a particle size of 100-200 mesh, and after grading and screening, a bamboo-based activated carbon source for semiconductor-grade silicon carbide crystal synthesis is obtained.

[0014] Furthermore, before the S3 carbonization treatment, the bamboo powder needs to be treated in a multi-stage gradient manner. The specific implementation process is as follows: ① Alkali leaching for impurity removal: Add the dried bamboo powder to a sodium hydroxide solution and treat it with ultrasound for 2-3 hours. Filter and wash with deionized water until the pH of the filtrate is 7.0±0.2; ② Acid washing for impurity removal: Add the alkaline-leached bamboo powder to a pure hydrochloric acid solution and stir for 1.5-2 hours. Filter and wash with deionized water until the pH of the filtrate is 7.0±0.2; ③ Vacuum drying: Place the acid-washed bamboo powder in a vacuum freeze-drying oven and dry for 10-12 hours to obtain impurity-free bamboo powder.

[0015] Furthermore, in S1, healthy moso bamboo is 4-6 years old and 5-8 cm in diameter. The bamboo nodes, green bamboo, and yellow bamboo need to be removed within one week after felling. The particle size of the crushed bamboo powder is 20-40 mesh. During the soaking process, the deionized water needs to be changed every 8 hours. The drying oven is set to -40~-30℃ and vacuum degree ≤10Pa for 12-16 hours. The conductivity of the deionized water is ≤10μS / cm.

[0016] Furthermore, in S2, ① the mass concentration of the sodium hydroxide solution is 5-8%, and the ultrasonic treatment is set at a frequency of 40-60kHz and a temperature of 50-60℃; ② during pickling, the mass concentration of the hydrochloric acid solution is 3-5%, and the treatment is carried out at a temperature of 60-70℃ and a stirring rate of 150-200r / min; ③ the working environment inside the vacuum freeze-drying oven is -35~-25℃ and the vacuum degree is ≤10Pa.

[0017] Furthermore, the inert gas is either N2 or Ar. In S3, the inert gas flow rate is 50-80 mL / min; the temperature is increased to 700-1200℃ at a heating rate of 10-20℃ / min, and calcined for 5-7 h. In S5, the inert gas flow rate is 60-100 mL / min; the temperature is increased to 800-1500℃ at a heating rate of 10-20℃ / min, and calcined for 3-5 h.

[0018] Furthermore, in S4, the particle size prepared by the Raymond mill is D50=25~75μm, and in S5, the solid-liquid ratio of bamboo charcoal powder and oxidant is 5:1~5.

[0019] Furthermore, the protective gas in the S6 atmosphere tube furnace is either N2 or Ar, and the volume ratio of water vapor to carbon dioxide is 1:2-1:3, and the flow rate of the mixed gas is 60-100 mL / min; the temperature is raised to 900-1000℃ at a heating rate of 2-3℃ / min and held for 2-3 hours.

[0020] Furthermore, in S7, the protective gas is heated to 2000~2400℃ at a heating rate of 100-200℃ / min.

[0021] Compared with the prior art, the beneficial effects of this invention are as follows: using bamboo as raw material, and through processes such as carbonization, grinding, pre-oxidation, and purification, a porous active carbon source is obtained. This carbon source has abundant pores, and in terms of carbonization, pre-oxidation, and purification processes, it has progressive significance in the synthesis process of semiconductor-grade silicon carbide grains, whether compared to natural flake graphite carbon sources or relatively dense artificial carbon sources such as petroleum coke and pitch coke.

[0022] In this invention, a multi-stage gradient alkaline leaching-acid washing impurity removal pretreatment is combined with a high-temperature halogen organic gas purification process. Halogen elements react with impurities to generate gaseous metal halides and are completely discharged, so that the bamboo-based activated carbon source reaches 6N grade purity, the ash content is reduced, and the content of metal impurities such as Al, Fe, and Na is reduced to below 1 ppm, which fully meets the stringent requirements for carbon source purity in semiconductor-grade silicon carbide grain synthesis.

[0023] Meanwhile, in this invention, the pre-oxidation treatment increases the spacing between disordered carbon layers in bamboo charcoal. Combined with a precise temperature-controlled activation process, the pore structure of bamboo-based activated carbon can be precisely controlled, so that its specific surface area reaches 800-1200 m² / g, and the micropores and mesopores are evenly distributed. This provides a stable mass transfer channel and reaction interface for the silicon carbide synthesis reaction, and greatly improves the reactivity and uniformity of the carbon source and silicon source. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0025] Figure 1 This is a flowchart illustrating the structure of the present invention. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0027] The present invention will be further described below with reference to embodiments.

[0028] Example 1:

[0029] A method for preparing a bamboo-based activated carbon source for semiconductor-grade silicon carbide grain synthesis includes the following steps:

[0030] S1: Raw material screening and pretreatment. Select healthy moso bamboo, which is 4 years old and 5cm in diameter. Remove bamboo nodes, bamboo green and bamboo yellow within one week after felling. The particle size of the crushed bamboo powder is 20-40 mesh. Cut the bamboo material from the middle part and crush it to obtain bamboo powder. Soak the bamboo powder in deionized water. Then place the soaked bamboo powder in a vacuum freeze-drying oven to obtain dried bamboo powder. During the soaking process, the deionized water needs to be changed every 8 hours. The drying oven is set to -40~-30℃ and vacuum degree ≤10Pa for 12 hours. The conductivity of the deionized water is ≤10μS / cm.

[0031] S2: Impurity Removal Treatment; ① Alkali Immersion: Add dried bamboo powder to a sodium hydroxide solution with a mass concentration of 5%. During ultrasonic treatment, set the frequency to 40kHz and the temperature to 50℃, and use ultrasonic treatment for 2 hours. Filter and wash with deionized water until the pH of the filtrate is 7.0±0.2; ② Acid Washing: Add the alkaline-immersed bamboo powder to a pure hydrochloric acid solution with a mass concentration of 3%. During acid washing, stir at 60℃ and a stirring rate of 150r / min for 1.5 hours. Filter and wash with deionized water until the pH of the filtrate is 7.0±0.2; ③ Vacuum Drying: Place the acid-washed bamboo powder in a vacuum freeze-drying oven with a working environment of -35℃ and a vacuum degree ≤10Pa. Dry for 10 hours to obtain impurity-removed bamboo powder;

[0032] S3: Carbonization treatment: Place the cleaned bamboo powder in a sealed, oxygen-free calcining furnace, and introduce inert gas as a protective gas with a flow rate of 50 mL / min; heat to 700℃ at a heating rate of 10℃ / min, calcine for 5 hours, and then cool to room temperature under an inert atmosphere to obtain bamboo charcoal.

[0033] S4: Grinding process, the carbonized bamboo charcoal is ground into powder using a Raymond mill to obtain bamboo charcoal powder. The particle size prepared by the Raymond mill is D50=25~75μm. In S5, the solid-liquid ratio of bamboo charcoal powder and oxidant is 5:1.

[0034] S5: Pre-oxidation treatment: The bamboo charcoal powder obtained by grinding is mixed with the oxidant according to the solid-liquid ratio, placed in a calcining furnace, and an inert gas is introduced as a protective gas with a flow rate of 60 mL / min; the temperature is increased to 800℃ at a heating rate of 10℃ / min, and calcined for 3 hours to complete the pre-oxidation treatment and obtain pre-oxidized bamboo charcoal powder. The type of inert gas is the same as that in S3, which is one of N2 and Ar.

[0035] S6: Place the pre-oxidized bamboo charcoal powder in an atmosphere tube furnace. The protective gas in the furnace is either N2 or Ar. A mixed activation gas of high-purity water vapor and high-purity carbon dioxide is introduced, with a volume ratio of water vapor to carbon dioxide of 1:2-1:3 and a flow rate of 60 mL / min. The temperature is raised to 900℃ at a rate of 2℃ / min and held for 2 hours. After activation, inert gas is introduced to cool the mixture to room temperature, thus obtaining crude bamboo-based activated carbon.

[0036] S7: The crude bamboo-based activated carbon is loaded into a graphite jar and then into a purification furnace. Ar gas is introduced as a protective gas, and the temperature is increased to 2000℃ at a heating rate of 100℃ / min. A special organic gas containing halogen elements is then introduced and the process is carried out for 10 hours. After the organic gas decomposes at high temperature, the halogen elements react with the impurities in the bamboo charcoal to form gaseous metal halides, which are discharged from the purification furnace system through a vacuum system to achieve 6N-level purification of the bamboo charcoal carbon source. After purification, Ar gas is introduced again to cool to room temperature to obtain refined bamboo-based activated carbon.

[0037] S8: Crushing and Grading: The refined bamboo-based activated carbon is crushed to a particle size of 100 mesh and then graded and screened to obtain a bamboo-based activated carbon source for the synthesis of semiconductor-grade silicon carbide crystals.

[0038] Using bamboo as raw material, a porous activated carbon source is obtained through processes such as carbonization, grinding, pre-oxidation, and purification. This carbon source has abundant pores and represents a significant advancement in the synthesis process of semiconductor-grade silicon carbide grains, whether compared to natural flake graphite carbon sources or relatively dense artificial carbon sources such as petroleum coke and pitch coke.

[0039] Example 2:

[0040] S1: Raw material screening and pretreatment. Select healthy moso bamboo, which is 6 years old and 8cm in diameter. Remove bamboo nodes, bamboo green and bamboo yellow within one week after felling. The particle size of the crushed bamboo powder is 40 mesh. Cut the bamboo material from the middle part and crush it to obtain bamboo powder. Soak the bamboo powder in deionized water. Then place the soaked bamboo powder in a vacuum freeze-drying oven to obtain dried bamboo powder. During the soaking process, the deionized water needs to be changed every 8 hours. The drying oven is set at 30℃ and vacuum degree ≤10Pa for 116 hours. The conductivity of the deionized water is ≤10μS / cm.

[0041] S2: Impurity Removal Treatment; ① Alkali Immersion: Add dried bamboo powder to a sodium hydroxide solution with a mass concentration of 8%. During ultrasonic treatment, set the frequency to 60kHz and the temperature to 60℃, and treat with ultrasound for 3 hours. Filter and wash with deionized water until the pH of the filtrate is 7.0±0.2; ② Acid Washing: Add the alkali-immersed bamboo powder to a pure hydrochloric acid solution with a mass concentration of 5%. During acid washing, stir at 70℃ and a stirring rate of 200r / min for 2 hours. Filter and wash with deionized water until the pH of the filtrate is 7.0±0.2; ③ Vacuum Drying: Place the acid-washed bamboo powder in a vacuum freeze-drying oven with a working environment of 5℃ and a vacuum degree ≤10Pa, and dry for 12 hours to obtain impurity-removed bamboo powder;

[0042] S3: Carbonization treatment: Place the cleaned bamboo powder in a sealed, oxygen-free calcining furnace, and introduce inert gas as a protective gas with a flow rate of 80 mL / min; heat to 1200℃ at a heating rate of 20℃ / min, calcine for 7 hours, and then cool to room temperature under an inert atmosphere to obtain bamboo charcoal.

[0043] S4: Grinding process, the carbonized bamboo charcoal is ground into powder using a Raymond mill to obtain bamboo charcoal powder. The particle size prepared by the Raymond mill is D50=25~75μm. In S5, the solid-liquid ratio of bamboo charcoal powder and oxidant is 5:5.

[0044] S5: Pre-oxidation treatment: The bamboo charcoal powder obtained by grinding is mixed with the oxidant according to the solid-liquid ratio, placed in a calcining furnace, and an inert gas is introduced as a protective gas with a flow rate of 100 mL / min; the temperature is increased to 1500℃ at a heating rate of 20℃ / min, and calcined for 5 hours to complete the pre-oxidation treatment and obtain pre-oxidized bamboo charcoal powder. The type of inert gas is the same as that in S3, which is one of N2 and Ar.

[0045] S6: Place the pre-oxidized bamboo charcoal powder in an atmosphere tube furnace. The protective gas in the furnace is either N2 or Ar. A mixed activation gas of high-purity water vapor and high-purity carbon dioxide is introduced, with a volume ratio of water vapor to carbon dioxide of 1:3 and a flow rate of 100 mL / min. The temperature is raised to 1000℃ at a rate of 2-3℃ / min and held for 3 hours. After activation, inert gas is introduced to cool the mixture to room temperature to obtain crude bamboo-based activated carbon.

[0046] S7: The crude bamboo-based activated carbon is loaded into a graphite jar and then into a purification furnace. Ar gas is introduced as a protective gas, and the temperature is increased to 2400℃ at a heating rate of 200℃ / min. A special organic gas containing halogen elements is then introduced and the process is carried out for 20 hours. After the organic gas decomposes at high temperature, the halogen elements react with the impurities in the bamboo charcoal to form gaseous metal halides, which are discharged from the purification furnace system through a vacuum system, thus achieving 6N-level purification of the bamboo charcoal carbon source. After purification, Ar gas is introduced again to cool the carbon to room temperature, and refined bamboo-based activated carbon is obtained.

[0047] S8: Crushing and Grading: The refined bamboo-based activated carbon is crushed to a particle size of 200 mesh and then graded and screened to obtain a bamboo-based activated carbon source for the synthesis of semiconductor-grade silicon carbide crystals.

[0048] Through multi-stage gradient alkaline leaching-acid washing impurity removal pretreatment, combined with high-temperature halogen organic gas purification process, halogen elements react with impurities to generate gaseous metal halides and are completely discharged, so that the bamboo-based activated carbon source reaches 6N grade purity, the ash content is reduced, and the content of metal impurities such as Al, Fe, and Na is reduced to below 1ppm, which fully meets the stringent requirements for carbon source purity in semiconductor-grade silicon carbide grain synthesis.

[0049] Example 3:

[0050] S1: Raw material screening and pretreatment. Select healthy moso bamboo, which is 5 years old and 6cm in diameter. Remove bamboo nodes, bamboo green and bamboo yellow within one week after felling. The particle size of the crushed bamboo powder is 30 mesh. Cut the bamboo material from the middle part and crush it to obtain bamboo powder. Soak the bamboo powder in deionized water. Then place the soaked bamboo powder in a vacuum freeze-drying oven to obtain dried bamboo powder. During the soaking process, the deionized water needs to be changed every 8 hours. The drying oven is set to -5℃ and vacuum degree ≤10Pa for 14 hours. The conductivity of the deionized water is ≤10μS / cm.

[0051] S2: Impurity Removal Treatment; ① Alkali Immersion: Add dried bamboo powder to a sodium hydroxide solution with a mass concentration of 6%. During ultrasonic treatment, set the frequency to 50kHz and the temperature to 55℃, and treat with ultrasound for 2.5 hours. Filter and wash with deionized water until the pH of the filtrate is 7.0±0.2. ② Acid Washing: Add the alkali-immersed bamboo powder to a pure hydrochloric acid solution with a mass concentration of 4%. During acid washing, stir at 65℃ and a stirring rate of 175r / min for 1.5-2 hours. Filter and wash with deionized water until the pH of the filtrate is 7.0±0.2. ③ Vacuum Drying: Place the acid-washed bamboo powder in a vacuum freeze-drying oven with a working environment of -10℃ and a vacuum degree ≤10Pa. Dry for 11 hours to obtain impurity-removed bamboo powder.

[0052] S3: Carbonization treatment: Place the cleaned bamboo powder in a sealed, oxygen-free calcining furnace, and introduce inert gas as a protective gas with a flow rate of 70 mL / min; heat to 700~1200℃ at a heating rate of 15℃ / min, calcine for 5~7 hours, and then cool to room temperature under an inert atmosphere to obtain bamboo charcoal.

[0053] S4: Grinding process, the carbonized bamboo charcoal is ground into powder using a Raymond mill to obtain bamboo charcoal powder. The particle size prepared by the Raymond mill is D50=25~75μm. In S5, the solid-liquid ratio of bamboo charcoal powder and oxidant is 5:3.

[0054] S5: Pre-oxidation treatment: The bamboo charcoal powder obtained by grinding is mixed with the oxidant according to the solid-liquid ratio, placed in a calcining furnace, and an inert gas is introduced as a protective gas with a flow rate of 80 mL / min; the temperature is increased to 1250℃ at a heating rate of 15℃ / min, and calcined for 4 hours to complete the pre-oxidation treatment and obtain pre-oxidized bamboo charcoal powder. The type of inert gas is the same as that in S3, which is one of N2 and Ar.

[0055] S6: Place the pre-oxidized bamboo charcoal powder in an atmosphere tube furnace. The protective gas in the furnace is either N2 or Ar. A mixture of high-purity water vapor and high-purity carbon dioxide is introduced as an activation gas, with a volume ratio of water vapor to carbon dioxide of 1:2-1:3 and a flow rate of 80 mL / min. The temperature is raised to 900-1000℃ at a rate of 2.5℃ / min and held for 2-3 hours. After activation, an inert gas is introduced to cool the mixture to room temperature, thus obtaining crude bamboo-based activated carbon.

[0056] S7: The crude bamboo-based activated carbon is loaded into a graphite jar and then into a purification furnace. Ar gas is introduced as a protective gas, and the temperature is increased to 2000~2400℃ at a heating rate of 100-200℃ / min. A special organic gas containing halogen elements is introduced and the process is carried out for 10~20 hours. After the organic gas decomposes at high temperature, the halogen elements react with the impurity elements in the bamboo charcoal to form gaseous metal halides, which are discharged from the purification furnace system through a vacuum system to achieve 6N-level purification of the bamboo charcoal carbon source. After purification, Ar gas is introduced to cool to room temperature to obtain refined bamboo-based activated carbon.

[0057] S8: Crushing and Grading: The refined bamboo-based activated carbon is crushed to a particle size of 100-200 mesh and then graded and screened to obtain a bamboo-based activated carbon source for the synthesis of semiconductor-grade silicon carbide crystals. Renewable bamboo is used as raw material to replace traditional non-renewable carbon sources. The preparation process does not accumulate harmful waste liquid or waste residue. The high-temperature purification and activation process does not cause secondary pollution and meets the requirements of green and sustainable development.

[0058] By increasing the spacing between disordered carbon layers in bamboo charcoal through pre-oxidation treatment, and combined with a precise temperature-controlled activation process, the pore structure of bamboo-based activated carbon can be precisely controlled, so that its specific surface area reaches 800-1200m² / g, and the micropores and mesopores are evenly distributed. This provides a stable mass transfer channel and reaction interface for the silicon carbide synthesis reaction, and greatly improves the reactivity and uniformity of the carbon source and silicon source.

[0059] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions will not cause the essence of the corresponding technical solutions to deviate from the protection scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a bamboo-based activated carbon source for the synthesis of semiconductor-grade silicon carbide grains, characterized in that, Includes the following steps: S1: Raw material screening and pretreatment: Select healthy moso bamboo, cut the bamboo material from the middle part, crush it to obtain bamboo powder; soak the bamboo powder in deionized water; then place the soaked bamboo powder in a vacuum freeze-drying oven to obtain dried bamboo powder. S2: Impurity removal treatment; removing impurities from the dried bamboo powder in S1 to obtain impurity-removed bamboo powder; S3: Carbonization treatment: Place the cleaned bamboo powder in a sealed, oxygen-free calcining furnace, introduce inert gas as a protective gas, calcine, and then cool to room temperature under the protection of an inert atmosphere to obtain bamboo charcoal. S4: Grinding process: The bamboo charcoal obtained by carbonization is ground into powder using a Raymond mill to obtain bamboo charcoal powder. S5: Pre-oxidation treatment: The bamboo charcoal powder obtained by grinding is mixed with the oxidant according to the solid-liquid ratio, placed in a calcining furnace, and inert gas is introduced as a protective gas for calcination to complete the pre-oxidation treatment and obtain pre-oxidized bamboo charcoal powder. S6: Place the pre-oxidized bamboo charcoal powder in an atmosphere tube furnace, switch the protective gas, and introduce a mixed activation gas of high-purity water vapor and high-purity carbon dioxide. After activation, continue to introduce inert gas to cool to room temperature to obtain crude bamboo-based activated carbon. S7: The crude bamboo-based activated carbon is loaded into a graphite jar, then into a purification furnace. Ar gas is introduced as a protective gas, and a special organic gas containing halogen elements is introduced for 10-20 hours. After the organic gas decomposes at high temperature, the halogen elements react with the impurities in the bamboo charcoal to form gaseous metal halides, which are discharged from the purification furnace system through a vacuum system to achieve 6N-level purification of the bamboo charcoal carbon source. After purification, Ar gas is continued to be introduced to cool to room temperature to obtain refined bamboo-based activated carbon. S8: Crushing and Grading: The refined bamboo-based activated carbon is crushed to a particle size of 100-200 mesh, and after grading and screening, a bamboo-based activated carbon source for semiconductor-grade silicon carbide crystal synthesis is obtained.

2. The method for preparing a bamboo-based activated carbon source for semiconductor-grade silicon carbide grain synthesis according to claim 1, characterized in that, Before S3 carbonization, the bamboo powder needs to be treated in a multi-stage gradient manner. The specific implementation process is as follows: ① Alkali leaching for impurity removal: Add the dried bamboo powder to a sodium hydroxide solution and treat it with ultrasound for 2-3 hours. Filter and wash with deionized water until the pH of the filtrate is 7.0±0.2; ② Acid washing for impurity removal: Add the alkaline-leached bamboo powder to a pure hydrochloric acid solution and stir for 1.5-2 hours. Filter and wash with deionized water until the pH of the filtrate is 7.0±0.2; ③ Vacuum drying: Place the acid-washed bamboo powder in a vacuum freeze-drying oven and dry for 10-12 hours to obtain impurity-free bamboo powder.

3. The method for preparing a bamboo-based activated carbon source for semiconductor-grade silicon carbide grain synthesis according to claim 1, characterized in that, In S1, healthy moso bamboo is 4-6 years old and 5-8cm in diameter. The bamboo nodes, green bamboo and yellow bamboo need to be removed within one week after felling. The particle size of the crushed bamboo powder is 20-40 mesh. During the soaking process, the deionized water needs to be changed every 8 hours. The drying oven is set to -40~-30℃ and vacuum degree ≤10Pa for 12-16 hours. The conductivity of the deionized water is ≤10μS / cm.

4. The method for preparing a bamboo-based activated carbon source for semiconductor-grade silicon carbide grain synthesis according to claim 1, characterized in that, In S2, ① the mass concentration of sodium hydroxide solution is 5-8%, and the ultrasonic treatment is set at a frequency of 40-60kHz and a temperature of 50-60℃. ② During pickling, the mass concentration of hydrochloric acid solution is 3-5%, and the treatment is carried out at a temperature of 60-70℃ and a stirring rate of 150-200r / min. ③ The working environment inside the vacuum freeze-drying oven is -35~-25℃ and the vacuum degree is ≤10Pa.

5. The method for preparing a bamboo-based activated carbon source for semiconductor-grade silicon carbide grain synthesis according to claim 4, characterized in that, The inert gas is either N2 or Ar. In S3, the inert gas flow rate is 50-80 mL / min; the temperature is increased to 700-1200℃ at a heating rate of 10-20℃ / min, and calcined for 5-7 h. In S5, the inert gas flow rate is 60-100 mL / min; the temperature is increased to 800-1500℃ at a heating rate of 10-20℃ / min, and calcined for 3-5 h.

6. The method for preparing a bamboo-based activated carbon source for semiconductor-grade silicon carbide grain synthesis according to claim 1, characterized in that, In S4, the particle size prepared by Raymond mill is D50=25~75μm, and in S5, the solid-liquid ratio of bamboo charcoal powder and oxidant is 5:1~5.

7. The method for preparing a bamboo-based activated carbon source for semiconductor-grade silicon carbide grain synthesis according to claim 1, characterized in that, The protective gas in the S6 atmosphere tube furnace is either N2 or Ar, and the volume ratio of water vapor to carbon dioxide is 1:2-1:3, and the flow rate of the mixed gas is 60-100 mL / min; the temperature is raised to 900-1000℃ at a heating rate of 2-3℃ / min and held for 2-3 hours.

8. The method for preparing a bamboo-based activated carbon source for semiconductor-grade silicon carbide grain synthesis according to claim 1, characterized in that, In S7, the protective gas is heated to 2000~2400℃ at a heating rate of 100-200℃ / min.

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