High-purity low-resistivity beta-silicon carbide material, preparation method and application thereof

Abstract

The application relates to the technical field of semiconductor component materials, in particular to a high-purity low-resistivity beta-phase silicon carbide material and a preparation method and application thereof. Specifically, the following steps are included: soaking clean rice husks in a weak acid aqueous solution, boiling in the acid aqueous solution before use, cleaning, drying and the like; low-temperature carbonizing the dried rice husks, ball milling and sieving after cooling; further heating and stirring in an alkaline aqueous solution in a water bath, filtering; the filtrate is a silicate aqueous solution B; drying the filter residue D; heat preservation of the filter residue D, washing after cooling, obtaining rice husk carbon E, drying; ball milling the silicate aqueous solution B and the rice husk carbon E, drying to constant weight, obtaining loose bulk F; calcining the loose bulk F, obtaining beta-SiC powder; mixing and sintering beta-SiC powder and ultrafine silicon carbide powder, obtaining a beta-SiC sintered body. The prepared silicon carbide material can meet the requirements of high purity and high density required in a semiconductor manufacturing process.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor component materials, in particular to a high-purity low-resistivity beta-phase silicon carbide material and a preparation method and application thereof. BACKGROUND

[0002] Silicon carbide material has similar electrical conductivity to silicon and good ion etching resistance. With the advancement of integrated circuit miniaturization, the demand for etching process for integrated circuit manufacturing is increasing, and the plasma power and energy for etching are continuously increasing, especially the plasma energy required in the capacitively coupled plasma (CCP) etching equipment. Therefore, the use of semiconductor precision components prepared from silicon carbide material is increasing.

[0003] Beta-SiC belongs to the cubic crystal system and has a zinc blende crystal structure, which can be synthesized at a temperature below 1700℃, much lower than the temperature required in the synthesis of alpha-SiC. Therefore, the sintering reaction activity in the synthesis of beta-SiC is better, the particles are easier to refine and homogenize, and a large amount of nano, sub-micron and micron ultra-fine powders can be produced. The C-rich raw materials used to synthesize beta-SiC include activated carbon and carbon black; Si-rich raw materials include Si, SiO2, silane, etc.

[0004] Under the same sintering process, the resistivity of beta-SiC powder is always lower than that of alpha-SiC powder. For semiconductor component silicon carbide materials that cannot add any metal oxide sintering aids, beta-SiC is more suitable for the requirements of high purity and low resistivity of some semiconductor components. However, the cost of beta-SiC powder is several times that of alpha-SiC powder, which is a valuable and scarce raw material. It has not been commercially applied in China, and the existing coarse powder synthesis method cannot meet the high purity requirements of semiconductor manufacturing environment. In addition, the sintering process of SiC involves batching, mixing, granulation, molding, debinding, and sintering, and impurities may be introduced at each stage, making it difficult to maintain the purity of the raw powder. Finally, whether it is traditional solid-phase sintering or liquid-phase sintering in industry, sintering aids must be added, which sharply reduces the purity of the material, especially the introduction of metal elements. The impact of components containing metal impurities on wafer manufacturing environment is fatal. Therefore, it is difficult to prepare high-purity low-resistivity beta-phase silicon carbide material using traditional industrial sintering methods with powder as raw material.

[0005] At present, the process of preparing silicon carbide powder mostly adopts high-purity silicon powder and high-carbon materials to be mixed and sintered under high-temperature conditions, and the conditions are high temperature, high pressure and air isolation. Because the solid-phase reaction is generally difficult to complete, air oxidation and acid washing are still needed after the reaction to obtain high-purity SiC powder. At present, there are methods for preparing high-purity SiC powder, but few methods are for preparing high-purity β-SiC powder. Recently, the purity research mainly focuses on α-SiC powder used as raw material for the third-generation semiconductor silicon carbide wafer.

[0006] A method for preparing high-purity silicon carbide raw material is disclosed in the related art, and the obtained D50 is 50-800 μm, the purity of the silicon carbide powder is > 99.999%, and the silicon carbide powder is used for producing silicon carbide wafers, the main crystal phase is α phase, and is not suitable for preparing silicon carbide semiconductor parts.

[0007] A method for preparing low-temperature and low-cost high-purity silicon carbide ultrafine particles is disclosed in the related art, and the waste generated by cutting a single crystal silicon rod is treated to be used as a high-purity silicon source, is put into a vacuum sintering furnace, and hydrogen and argon gases are introduced to realize full carbonization of the silicon powder to obtain high-purity silicon carbide powder, but the purity value of the obtained silicon carbide powder is not clear.

[0008] It is also disclosed in the related art that methyl dichlorosilane and sodium tetrahydroaluminate are used to synthesize methylsilane, and the crude methylsilane generated in the reaction is separated and purified to 6N level by separation and purification technology, and is used as a raw material for producing high-purity silicon carbide powder. However, the method for preparing silicon carbide powder and the purity are not mentioned.

[0009] In the field of silicon carbide parts for semiconductor equipment, domestic and foreign enterprises generally use the chemical vapor deposition (CVD) method for production, and the purity can reach more than 5N to meet the requirements of high purity, corrosion resistance and plasma etching required for semiconductor manufacturing. However, this method not only has toxic raw materials, dangerous reaction, flammable and explosive by-products, and difficult to clean the furnace cavity, but also has theoretical limitations in deposition rate, which cannot quickly react and synthesize silicon carbide materials. Especially for disc parts with a thickness of more than 4mm, due to the limitation of the supporting base tool, it must be deposited more than twice, otherwise defects will be left on the material, which will cause the product to be unusable. In addition, the deposition amount of the disc is large, and the single deposition time is greatly prolonged compared with the ring product, which brings long time, high cost, slow cycle and high risk to the manufacturing of silicon carbide materials, and is not convenient for batch production and manufacturing. However, with the continuous improvement of semiconductor process, the requirements and use frequency of semiconductor equipment are increasing. Taking silicon carbide electrodes as an example, the diameter of the current international mainstream products has reached more than 480mm, and the thickness is more than 12mm. Considering the subsequent machining sequence as subtractive manufacturing, the size specification of the material is higher.

[0010] Therefore, it is necessary to find a more efficient sintering method to realize the preparation of high-purity and low-resistivity β-phase silicon carbide material, so as to meet the requirements of high purity and low resistivity required by semiconductor manufacturing. SUMMARY

[0011] The application provides a high-purity and low-resistivity β-phase silicon carbide material and a preparation method and application thereof.

[0012] The application provides a method for preparing a high-purity and low-resistivity β-phase silicon carbide material by using a sintering method, and the prepared silicon carbide material can meet the requirements of high purity and low resistivity required by a semiconductor manufacturing process.

[0013] The silicon carbide material provided by the application is different from the third-generation semiconductor silicon carbide, and is not a material for growing a wafer to manufacture a silicon carbide chip, but is a device component material for semiconductor manufacturing. The purposes, manufacturing processes, microscopic crystal phases, and performance requirements of the two are different.

[0014] Rice husk is a biomass material rich in silicon and organic carbon, and has low cost and great potential. The composition and structure of the rice husk determine that it can be used to prepare high-quality silicon carbide material. Rice husk ash has the highest silicon content among agricultural wastes, and the silicon mainly exists in the form of amorphous structure, and therefore can be used as a silicon source. The SiO2 aggregate extracted from the rice husk ash is easy to break into nanoscale raw material particles, and the surface of the SiO2 aggregate has residual organic components, so that the SiO2 aggregate has high dispersibility and can fully play the high activity of the nanoscale raw material, so that the subsequent synthesis reaction can be fully carried out at a lower temperature.

[0015] However, in addition to carbon and silicon required for preparing silicon carbide material, the rice husk also contains other metal elements. These metal elements will react with silicon dioxide during the carbonization process of the rice husk, form low-melting-point salts, and cause the material to agglomerate. The deionized water immersion method is used to pretreat the rice husk raw material, so as to remove the water-soluble metal elements in the rice husk. Research results show that the removal rate of K elements in the rice husk reaches 63% by water pretreatment, and the removal rate of the overall metal elements is 40%; more than 95% of the metal elements in the rice husk can be removed by inorganic acid pretreatment, which greatly ensures the removal of the metal elements in the rice husk. In comparison, the effect of removing the metal elements in the rice husk by using organic acid (acetic acid) is not as good.

[0016] In a first aspect, the application provides a preparation method of a high-purity and low-resistivity β-phase silicon carbide material, and the following technical scheme is adopted:

[0017] The preparation method of the high-purity and low-resistivity β-phase silicon carbide material specifically includes the following steps:

[0018] (1) Mix rice husk with water according to a volume ratio of 1: (1-5), take the upper layer rice husk after fully stirring, and place it in a weak acid aqueous solution for standby; before use, boil the rice husk in the acid aqueous solution for 2-5 times, clean, and dry;

[0019] (2) Place the dried rice husk in a low-oxygen environment at 450-600°C for 1-6h, cool, and ball mill at a speed of 100-200r / min for 1-4h to obtain carbonized rice husk powder; sieve the carbonized rice husk powder through a 150-300 mesh sieve to obtain sieved carbonized rice husk powder A;

[0020] (3) Stir the sieved carbonized rice husk powder A and 10-50wt% alkali aqueous solution in a water bath at 90-100°C for 2-4h, and filter; the obtained filtrate is a silicate aqueous solution B; and the obtained filter residue D is dried;

[0021] (4) Place the filter residue D in a vacuum or inert gas protection environment at 600-800°C for 1-3h, wash to neutral after cooling, and obtain rice husk carbon E, and dry;

[0022] (5) Mix the silicate aqueous solution B and the rice husk carbon E according to a molar ratio of carbon to silicon of 2.3-2.5, ball mill at a speed of 100-200r / min for 1-2h, and dry to constant weight to obtain loose bulk F;

[0023] (6) Slowly calcine the loose bulk F at 1500-1850°C to obtain β-SiC powder;

[0024] (7) Mix the β-SiC powder with 1-30wt.% ultra-fine silicon carbide powder with an average particle size of 10-100nm, and sinter at 1900-2000°C and 30-50MPa to obtain a β-SiC sintered body.

[0025] The purity of the above β-SiC sintered body is higher than 99.99% and the volume resistivity is ≤0.5Ω·cm.

[0026] Optionally, in step (1), the acid in the weak acid aqueous solution and the acid aqueous solution is an inorganic acid.

[0027] Optionally, in step (1), the acid in the weak acid aqueous solution and the acid aqueous solution is at least one of hydrochloric acid, sulfuric acid, nitric acid, and acetic acid.

[0028] Optionally, in step (2), the material of the fine sieve is an organic material and cannot contain metal elements.

[0029] Optionally, the material of the fine sieve is a plastic material.

[0030] Optionally, in step (3), the base in the aqueous base solution is at least one of ammonia and an organic base, the purity of the base is higher than 99% and the base cannot contain metal elements.

[0031] Optionally, the base in the aqueous base solution must contain nitrogen elements.

[0032] In a second aspect, the application provides a high-purity low-resistivity β-SiC material prepared by the above preparation method.

[0033] In a third aspect, the application provides an application of the above high-purity low-resistivity β-SiC material as a component material for semiconductor manufacturing.

[0034] In summary, the application includes at least one of the following beneficial technical effects:

[0035] 1. The application extracts high-activity silicon source and carbon source from rice husks for synthesizing high-purity β-SiC powder, and creatively introduces a sufficient amount of nitrogen elements in the powder synthesis reaction process, greatly improving the doping amount of nitrogen elements and providing a good doping basis for the preparation of low-resistivity semiconductor component electrodes.

[0036] 2. The application uses low-cost crop waste as raw material to synthesize high-value-added β-SiC powder at a lower temperature, and successfully prepares high-purity low-resistivity β-SiC sintered bodies that can be used as semiconductor component materials.

[0037] 3. The application uses renewable biomass resources as raw materials, and rice husks have the characteristics of zero pollution, wide sources, and large reserves. The recycling of rice husks solves the problem of crop waste disposal and realizes the economic benefits of renewable resources.

[0038] 4. In the process of synthesizing β-SiC powder and β-SiC sintered bodies, no toxic and harmful raw materials and chemical reagents are used, and it is environmentally friendly and sustainable. BRIEF DESCRIPTION OF DRAWINGS

[0039] Figure 1 XRD detection results of the SiC sintered body and SiC powder obtained in Example 1. DETAILED DESCRIPTION

[0040] Before describing the embodiments of the application in detail, it should be understood that the terms used herein are for the purpose of describing specific embodiments only. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the term belongs.

[0041] It should be noted that the terms "first", "second" are used only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined as "first", "second" can explicitly or implicitly include one or more of the features. Further, in the description of the present application, unless otherwise stated, the meaning of "a plurality" is two or more.

[0042] The endpoints of the ranges and any values disclosed in the present application are not limited to the precise values recited as the exact range or value should be understood as being encompassed by the ranges or values near them. For ranges, the endpoints are included as well as intervening points which are included in the small entity between the endpoints and that single point. New ranges can be created from the combination of the endpoints and the single points.

[0043] In the present application, the term "comprising" or "including" is an open-ended expression, that is, it includes the contents indicated in the present application, but does not exclude other contents.

[0044] The present application provides a preparation method of high-purity low-resistivity beta-phase silicon carbide material. The preparation method specifically comprises the following steps:

[0045] (1) Mix rice husk and water according to a volume ratio of 1:(1-5), stir thoroughly, and then take the upper layer of rice husk and soak it in a weak acid aqueous solution for standby. Before use, boil the rice husk in the acid aqueous solution for 2-5 times, wash with distilled water, and then dry the moisture. The acid in the weak acid aqueous solution and the acid aqueous solution is at least one of hydrochloric acid, sulfuric acid, nitric acid, and acetic acid.

[0046] (2) Put the dried rice husk obtained in step (1) into a heating furnace, heat at 450-600℃ in a low-oxygen environment for 1-6h, take it out after cooling, and put it into a ball mill at a rotating speed of 100-200r / min for 1-4h to obtain carbonized rice husk powder; pass through a 150-300 mesh fine screen, take the carbonized rice husk powder A under the screen for standby.

[0047] The material of the fine screen is an organic material and cannot contain metal elements. Specifically, it can be engineering plastics such as nylon (PA), polyethylene (PE), and polypropylene (PP).

[0048] (3) Heat and stir the carbonized rice husk powder A obtained in step (2) and 10-50wt% of an alkali aqueous solution in a water bath at 90-100℃ for 2-4h, and filter; the obtained filtrate is a silicate aqueous solution B for standby; and the obtained filter residue D is dried for standby.

[0049] The alkali in the alkali aqueous solution is at least one of ammonia and an organic base, and the purity of the alkali is higher than 99% and does not contain metal elements. In particular, the alkali aqueous solution must contain nitrogen elements.

[0050] (4) The residue D obtained in step (3) is placed in a vacuum furnace and heated at 600-800℃ under vacuum or inert gas protection for 1-3h. After cooling, it is taken out, washed to neutral, and dried to obtain rice husk carbon E, which is ready for use.

[0051] (5) The aqueous silicate solution B obtained in step (3) and the rice husk carbon E obtained in step (4) are mixed in a ball mill at a rotation speed of 100-200r / min for 1-2h, and then dried to constant weight in a vacuum oven to obtain loose bulk F.

[0052] (6) The loose bulk F obtained in step (5) is placed in a vacuum furnace and slowly calcined at 1500-1850℃ to obtain β-SiC powder with an average particle diameter of 0.5-20μm.

[0053] (7) The β-SiC powder obtained in step (6) is mixed with 1-30wt.% of ultra-fine silicon carbide powder with an average particle diameter of 10-100nm, and sintered in a hot-pressing furnace at 1900-2000℃ and 30-50MPa to obtain a β-SiC sintered body. The purity of the β-SiC sintered body is higher than 99.99% and the volume resistivity is ≤0.5Ω·cm.

[0054] In addition, nano-sized β-SiC powder can be prepared using a sol-gel method combined with carbothermal reduction. However, the sol-gel method is a liquid-phase synthesis method, which is difficult to be industrialized, and the purity of the reaction product is difficult to control. To obtain high-purity silicon carbide powder, high-purity (5N or above) and metal impurity-free organic raw materials are required. The reaction catalysts that can be used in this method include nickel salts and iron salts, which have the risk of introducing metal elements, and are not suitable for preparing semiconductor component materials.

[0055] In addition, although other biomass resources such as straw can be used instead of rice husk, rod-shaped crops need to be cut before soaking and removing impurities, and the cutting equipment may involve the introduction of metal impurities.

[0056] In order to make the purpose, technical solutions and advantages of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application. The embodiments described below are exemplary and are only used to explain the present application, and cannot be understood as a limitation of the present application.

[0057] Unless otherwise specified, the specific techniques or conditions in the examples are carried out according to the techniques or conditions described in the literature or according to the product instructions. Unless otherwise specified, the reagents or instruments used are conventional products that can be obtained commercially.

[0058] The application is further described in detail below in conjunction with the examples and test results.

[0059] Example 1

[0060] The present embodiment provides a preparation method of a high-purity low-resistivity β-phase silicon carbide material.

[0061] The preparation method specifically comprises the following steps:

[0062] (1) Mix rice husks and deionized water at a volume ratio of 1:3, fully stir, take the upper layer of rice husks, and soak in a weakly acidic hydrochloric acid aqueous solution for standby. Before use, boil the upper layer of rice husks in the dilute hydrochloric acid aqueous solution for 3 times, repeatedly wash with distilled water, and dry the moisture.

[0063] (2) Put the rice husks obtained by drying in step (1) into a heating furnace, heat at 500°C for 4h in a low-oxygen environment, take out after cooling, put into a ball mill at a rotating speed of 150r / min for 2h, and obtain carbonized rice husk powder; pass through a 200-mesh nylon (PA) screen, take the carbonized rice husk powder A under the screen, and reserve for standby.

[0064] (3) Stir the carbonized rice husk powder A obtained in step (2) and a 25wt% ammonia water solution in a water bath at 90°C for 4h, and filter. The obtained filtrate is a silicate aqueous solution B, which is reserved for standby; and the obtained filter residue D is dried for standby.

[0065] (4) Put the filter residue D obtained in step (3) into a vacuum furnace, heat at 700°C in a vacuum environment for 2h, take out after cooling, wash to neutral, and obtain rice husk carbon E, which is dried for standby.

[0066] (5) According to the molar ratio of carbon to silicon of 2.5, put the silicate aqueous solution B obtained in step (3) and the rice husk carbon E obtained in step (4) into a ball mill and stir at a rotating speed of 100r / min for 2h, take out and put into a vacuum oven to dry to constant weight, and obtain loose bulk F.

[0067] (6) Put the loose bulk F obtained in step (5) into a vacuum furnace, slowly burn at 1650°C, and obtain β-SiC powder.

[0068] (7) Mix the β-SiC powder obtained in step (6) with 20wt.% of silicon carbide powder with an average particle size of 50nm, put into a hot-pressing furnace, sinter at 2000°C and 30MPa, and obtain a β-SiC sintered body.

[0069] Example 2

[0070] The embodiment provides a preparation method of high-purity low-resistivity beta-phase silicon carbide material.

[0071] The preparation method specifically comprises the following steps:

[0072] (1) rice husks and deionized water are mixed according to a volume ratio of 1:5, the upper layer rice husks are taken after sufficient stirring, and the rice husks are soaked in a weak-acid sulfuric acid aqueous solution for standby use. Before use, the upper layer rice husks are boiled in a nitric acid aqueous solution twice, and then washed repeatedly with distilled water, and dried.

[0073] (2) the dried rice husks obtained in step (1) are placed in a heating furnace, and heat preservation is performed at 600 DEG C in a low-oxygen environment for 3h, and then the rice husks are taken out after cooling, and then the rice husks are placed in a ball mill and ball milled at a rotating speed of 100r / min for 4h to obtain carbonized rice husk powder; the carbonized rice husk powder A is obtained by passing the carbonized rice husk powder through a 150-mesh polypropylene (PP) screen, and the carbonized rice husk powder A is used for standby.

[0074] (3) the carbonized rice husk powder A obtained in step (2) is mixed with 30wt.% polyethyleneimine aqueous solution, and then heated and stirred in a water bath at 90 DEG C for 3h, and then the filtrate is obtained by filtration, and the filtrate is used as silicate aqueous solution B for standby use, and the obtained residue D is dried for standby use.

[0075] (4) the residue D obtained in step (3) is placed in a vacuum furnace, and heat preservation is performed at 800 DEG C under the protection of argon gas for 1.5h, and then the residue D is taken out after cooling, and then washed until neutral to obtain rice husk carbon E for standby use.

[0076] (5) the silicate aqueous solution B obtained in step (4) and the rice husk carbon E obtained in step (4) are dosed according to a molar ratio of carbon to silicon of 2.4, and then placed in a ball mill and ball milled at a rotating speed of 200r / min for 1h, and then taken out and placed in a vacuum oven and dried to constant weight to obtain loose bulk F.

[0077] (6) the loose bulk F obtained in step (5) is placed in a vacuum furnace, and slowly calcined at 1700 DEG C to obtain beta-SiC powder.

[0078] (7) the beta-SiC powder obtained in step (6) is mixed with 8wt.% ultrafine silicon carbide powder with an average particle size of 80nm, and then placed in a hot-pressing furnace and sintered at 1950 DEG C and 40MPa to obtain a beta-SiC sintered body.

[0079] Embodiment 3

[0080] The embodiment provides a preparation method of high-purity low-resistivity beta-phase silicon carbide material.

[0081] The preparation method specifically comprises the following steps:

[0082] (1) Mix rice husk with deionized water according to a volume ratio of 1:2, fully stir, take the upper layer of rice husk, and soak in a weakly acidic sulfuric acid aqueous solution for standby; before use, boil the upper layer of rice husk in the sulfuric acid aqueous solution for 5 times, repeatedly clean with distilled water, and dry.

[0083] (2) Put the rice husk obtained by drying in step (1) into a heating furnace, heat at 450°C for 6h in a low oxygen environment, take out after cooling with the furnace, put into a ball mill, and ball mill at a rotating speed of 200r / min for 1h to obtain carbonized rice husk powder; pass through a 300-mesh polyethylene (PE) screen, take the carbonized rice husk powder A under the screen, and reserve for standby.

[0084] (3) Stir the carbonized rice husk powder A obtained in step (2) and 15wt% ammonia water solution in a 100°C water bath for 2h, filter the obtained filtrate to obtain a silicate aqueous solution B for standby; dry the obtained filter residue D for standby.

[0085] (4) Put the filter residue D obtained in step (3) into a vacuum furnace, heat at 650°C under vacuum for 3h, take out after cooling with the furnace, wash to neutral, and obtain rice husk carbon E, and dry for standby.

[0086] (5) According to a molar ratio of carbon to silicon of 2.3, put the silicate aqueous solution B obtained in step (3) and the rice husk carbon E obtained in step (4) into a ball mill and ball mill at a rotating speed of 150r / min for 2h, take out, and put into a vacuum oven to dry to constant weight to obtain loose bulk F.

[0087] (6) Put the loose bulk F obtained in step (5) into a vacuum furnace, slowly calcine at 1800°C to obtain β-SiC powder.

[0088] (7) Mix the β-SiC powder obtained in step (6) with 25wt.% of ultrafine silicon carbide powder with an average particle size of 30nm, put into a hot-pressing furnace, sinter at 1900°C and 48MPa, and obtain a β-SiC sintered body.

[0089] Comparative Example

[0090] Comparative Example 1

[0091] This comparative example provides a preparation method of a high-purity low-resistivity β-phase silicon carbide material. The difference between this comparative example and Example 1 is that in step (1), the rice husk is directly soaked in deionized water without soaking in a weakly acidic hydrochloric acid aqueous solution. The rest is consistent with Example 1.

[0092] Comparative Example 2

[0093] The present comparative example provides a preparation method of high-purity low-resistivity β-phase silicon carbide material. The present comparative example differs from Example 1 in that the rice husks in step (1) are directly cleaned and dried after being soaked in a weakly acidic aqueous hydrochloric acid solution, and the standby rice husks are not boiled in a dilute aqueous hydrochloric acid solution and then washed with water. The rest is consistent with Example 1.

[0094] Comparative Example 3

[0095] The present comparative example provides a preparation method of high-purity low-resistivity β-phase silicon carbide material. The present comparative example differs from Example 1 in that the weakly acidic aqueous solution and the acid added to the acidic aqueous solution in step (1) are both acetic acid. The rest is consistent with Example 1.

[0096] Comparative Example 4

[0097] The present comparative example provides a preparation method of high-purity low-resistivity β-phase silicon carbide material. The present comparative example differs from Example 1 in that the sieve used in step (2) is a metal standard sieve of the same mesh number. The rest is consistent with Example 1.

[0098] Comparative Example 5

[0099] The present comparative example provides a preparation method of high-purity low-resistivity β-phase silicon carbide material. The present comparative example differs from Example 1 in that the base used in step (3) is sodium hydroxide. The rest is consistent with Example 1.

[0100] Comparative Example 6

[0101] The present comparative example provides a preparation method of high-purity low-resistivity β-phase silicon carbide material. The present comparative example differs from Example 1 in that the base used in step (3) is potassium hydroxide, and no nitrogen element is introduced; and the sintering in step (7) is completed in a nitrogen atmosphere. The rest is consistent with Example 1.

[0102] Performance detection results

[0103] (I) Crystal type detection

[0104] The crystal type of the β-SiC sintered body prepared in the above Example 1 is detected.

[0105] The detection method is as follows:

[0106] Sample preparation: The sintered body is selected to have a flat and smooth plane, with a thickness of 1-5 mm and a length and width of 15 mm; the synthesized powder is required to pass through a 320-mesh sieve and has a mass of >5 g.

[0107] The phase composition of the SiC sintered body and the synthesized powder was analyzed using an X-ray diffractometer (XRD) with a Cu K target as the radiation source and a wavelength of 1.5406 A, and the 2θ angle was in the range of 20° to 80°.

[0108] The detection results are shown in Table 1. Figure 1 As shown in Table 1, (a) is the result of the SiC sintered body obtained in step (7), and (b) is the result of the SiC powder obtained in step (6). By comparing the detection results with the standard PDF card, SiC is the only crystal phase in both, and exists in the form of β phase (3C). Figure 1

[0109] (II) The metal ion content, purity, and resistivity of the β-SiC sintered bodies prepared in the above examples and comparative examples were detected, respectively. The detection method is as follows:

[0110] (1) Purity and metal ion content: the elemental composition and content of the obtained bulk were tested and analyzed by glow discharge mass spectrometry (GDMS), and the sample size was not less than 20*20*10 mm.

[0111] (2) Resistivity: a four-probe resistivity tester was used to test the volume resistivity (unit: Ω·cm) of the obtained bulk, and the sample thickness was measured using a vernier caliper / micrometer.

[0112] The detection results are shown in Table 1.

[0113] Table 1 Detection results of the above examples and comparative examples

[0114]

[0115]

[0116] As can be seen from Table 1, the purity of the β-SiC sintered bodies obtained in Examples 1-3 is higher than 99.99%, and the highest can reach 99.999%; the overall content of metal ions is low; the volume resistivity is ≤0.5 Ω·cm, and the lowest can reach 10 -3 Ω·cm. However, in Comparative Examples 1-3, the acid washing and water washing processes were not sufficient, and the metal impurities in the rice husk composition were not completely removed, resulting in a high content of some impurities and a decrease in purity; in Comparative Example 4, a metal standard sieve was used in the production process, resulting in a high content of metal impurities and a low purity; in Comparative Example 5, sodium hydroxide was used as the alkali, resulting in a high content of sodium ions, and no nitrogen element was involved in the synthesis reaction, resulting in a high resistivity; in Comparative Example 6, nitrogen was not introduced in the synthesis powder stage, and only nitrogen gas was used in the final hot-pressing sintering stage, resulting in a resistivity higher than 1 Ω·cm.

[0117] ​In the description of the specification, the description of the terms "one embodiment", "some embodiments", "example", "specific example" or "some examples" etc. means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are contained in at least one embodiment or example of the present application. In the description of the specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples. In addition, those skilled in the art can combine and combine the different embodiments or examples described in the specification and the features of the different embodiments or examples without contradiction.

[0118] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solution deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for preparing a high-purity, low-resistivity β-phase silicon carbide material, characterized in that, The preparation method specifically includes the following steps: (1) Mix rice husks and water in a volume ratio of 1:(1-5), stir thoroughly, and then take out the upper layer of rice husks and place them in a weakly acidic aqueous solution for later use. Before use, boil the rice husks in an acidic aqueous solution 2-5 times, wash and dry them. (2) Place the dried rice husks in a low-oxygen environment at 450-600℃ for 1-6 hours, cool them, and then ball mill them at a speed of 100-200r / min for 1-4 hours to obtain carbonized rice husk powder; pass them through a 150-300 mesh sieve and keep the carbonized rice husk powder A that is sieved through the sieve. (3) The carbonized rice husk powder A is heated and stirred in a water bath at 90-100℃ for 2-4 hours with a 10-50wt% alkaline aqueous solution, and then filtered; the resulting filtrate is a silicate aqueous solution B; the resulting filter residue D is dried; the alkali in the alkaline aqueous solution must contain nitrogen. (4) Place the filter residue D at 600-800℃ under vacuum or inert gas protection for 1-3 hours, cool, and wash until neutral. Obtain carbon E from rice husks and dry them; (5) The silicate aqueous solution B and the rice husk carbon E are mixed at a carbon to silicon molar ratio of 2.3-2.5, ball-milled at a speed of 100-200 r / min for 1-2 h, and dried to constant weight to obtain loose block F; (6) The loose block F is slowly calcined at 1500-1850℃ to obtain β-SiC powder; (7) The β-SiC powder is mixed with 1-30 wt.% of ultrafine silicon carbide powder with an average particle size of 10-100 nm and sintered at 1900-2000 °C and 30-50 MPa to obtain the β-SiC sintered body.

2. The preparation method according to claim 1, characterized in that, The purity of the β-SiC sintered body is higher than 99.99% and the volume resistivity is ≤0.5Ω·cm.

3. The preparation method according to claim 1, characterized in that, In step (1), the acid in the weakly acidic aqueous solution and the acidic aqueous solution is an inorganic acid.

4. The preparation method according to claim 1, characterized in that, The acid in the weakly acidic aqueous solution and the acidic aqueous solution is at least one of hydrochloric acid, sulfuric acid, nitric acid, and acetic acid.

5. The preparation method according to claim 1, characterized in that, In step (2), the material of the fine sieve is an organic material and cannot contain metal elements.

6. The preparation method according to claim 5, characterized in that, The fine sieve is made of plastic.

7. The preparation method according to claim 1, characterized in that, In step (3), the alkali in the alkaline aqueous solution is at least one of ammonia and organic alkali, and the purity of the alkali is higher than 99% and it cannot contain metal elements.

8. A high-purity, low-resistivity β-phase silicon carbide material prepared by any one of claims 1-7.

9. The application of the high-purity, low-resistivity β-phase silicon carbide material of claim 8 as a component material for semiconductor manufacturing.

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