Silicon carbide powder and method for producing silicon carbide ingot using same

Abstract

To provide a silicon carbide powder capable of improving the growth rate of a silicon carbide ingot and lowering the defects of a silicon carbide wafer; and a method of manufacturing a silicon carbide wafer using the silicon carbide powder.SOLUTION: A silicon carbide powder includes carbon and silicon, wherein a particle circularity measured through 2D image analysis is 0.4 to 0.9. A particle ellipticity measured through the 2D image analysis may be 0.92 or more. A method of manufacturing a silicon carbide wafer comprises the steps of: preparing a silicon carbide powder comprising a silicon carbide powder carbon and silicon and having a particle circularity of 0.4 to 0.9 measured through 2D image analysis; growing a silicon carbide ingot using the silicon carbide powder; and processing the silicon carbide ingot.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The examples relate to methods of making silicon carbide powder and silicon carbide ingots. [Background technology]

[0002] Silicon carbide (SiC) has the advantages of being excellent in heat resistance and mechanical strength, being resistant to radiation, and being capable of being produced into large-diameter substrates. In addition, silicon carbide has excellent physical strength and chemical resistance, a large energy band gap, and a high electron saturation drift velocity and withstand voltage. Therefore, it is widely used not only in semiconductor devices that require high power, high efficiency, high withstand voltage, and large capacity, but also in abrasives, bearings, fireproof plates, etc.

[0003] Silicon carbide is produced by various methods, such as by heat treating or passing electricity through carbon raw materials such as silicon carbide waste. Conventional methods include the Acheson method, reaction sintering method, atmospheric sintering method, and CVD (chemical vapor deposition) method. However, such methods have a problem in that the carbon raw materials remain, and these residues act as impurities and may deteriorate the thermal, electrical, and mechanical properties of silicon carbide.

[0004] As an example, Japanese Patent Application Laid-Open No. 2002-326876 discloses a method of producing silicon carbide by reacting a silicon carbide precursor, which has been subjected to a heat treatment process, at a high temperature under an inert gas such as argon (Ar) in order to polymerize or cross-link a silicon source and a carbon source. However, this process involves a high-temperature heat treatment at 1,800°C to 2,100°C under vacuum or inert gas conditions, which results in problems such as high production costs and non-uniform powder size.

[0005] Furthermore, wafers used in the solar cell and semiconductor industries are manufactured by growing silicon ingots in crucibles made of graphite or the like, and during the manufacturing process, a considerable amount of silicon carbide waste is generated, as well as waste slurry containing silicon carbide, which is adsorbed on the inner walls of the crucible. However, until now, these wastes have been buried and disposed of, causing environmental problems and incurring high disposal costs. Summary of the Invention [Problem to be solved by the invention]

[0006] The embodiments provide a silicon carbide powder that improves the growth rate of a silicon carbide ingot and reduces defects in a silicon carbide wafer, and a method for manufacturing a silicon carbide wafer using the same. [Means for solving the problem]

[0007] The silicon carbide powder according to one embodiment includes carbon and silicon, and has a particle circularity of 0.4 to 0.9 as measured by two-dimensional image analysis.

[0008] In one embodiment, the ovality of the particles as measured by the two-dimensional image analysis may be greater than or equal to 0.92.

[0009] In one embodiment, the tortuosity of the particles measured by the two-dimensional image analysis may be 0.8 to 0.99.

[0010] In one embodiment, the particle elongation measured by the two-dimensional image analysis may be 0.7 to 0.95.

[0011] In one embodiment, the elongation of the charging space measured by the two-dimensional image analysis may be 0.6 to 0.9.

[0012] In one embodiment, the curvature of the charging space measured by the two-dimensional image analysis may be 0.8 to 0.95.

[0013] In one embodiment, the equivalent circular diameter measured by the two-dimensional image analysis may be between 200 μm and 350 μm.

[0014] In one embodiment, the equivalent circular diameter measured by the two-dimensional image analysis may be between 350 μm and 700 μm.

[0015] In one embodiment, the equivalent circular diameter measured by the two-dimensional image analysis may be between 800 μm and 3500 μm.

[0016] According to one embodiment, a method for manufacturing a silicon carbide wafer includes the steps of: preparing silicon carbide powder, the silicon carbide powder including carbon and silicon, and having a particle circularity of 0.4 to 0.9 as measured by two-dimensional image analysis; growing a silicon carbide ingot using the silicon carbide powder; and processing the silicon carbide ingot.

[0017] In one embodiment, in the step of growing the silicon carbide ingot, a crucible may be filled with the silicon carbide powder, and the porosity of the silicon carbide powder filled in the crucible may be 10 vol% to 50 vol%, and in the step of growing the silicon carbide ingot, a growth rate of the silicon carbide ingot may be 250 μm to 400 μm. Effect of the Invention

[0018] The silicon carbide powder according to the embodiment has a suitable range of particle circularity. The silicon carbide powder according to the embodiment can have a suitable range of particle ellipticity. The silicon carbide powder according to the embodiment can have a suitable range of particle curvature. The silicon carbide powder according to the embodiment can have a suitable range of particle elongation. The silicon carbide powder according to the embodiment can have a suitable range of charging space elongation. The silicon carbide powder according to the embodiment can have a suitable range of charging space curvature.

[0019] Accordingly, the silicon carbide powder according to the embodiment may have an appropriate shape so as to realize appropriate porosity and appropriate thermal conductivity when filled into a crucible to produce silicon carbide ingots and silicon carbide wafers.

[0020] As a result, the silicon carbide powder according to the embodiment has improved thermal conductivity in the horizontal direction when filled in the crucible, and has a suitable range of porosity, and therefore has a uniform temperature gradient in the horizontal direction when filled in the crucible and heated for growing the silicon carbide ingot, and silicon carbide gas sublimated in the pores can be easily transferred to the silicon carbide seed crystal.

[0021] As a result, the silicon carbide powder according to the embodiment can transport the sublimated silicon carbide gas upward at an improved and uniform rate. Therefore, the silicon carbide powder according to the embodiment can improve the growth rate of the silicon carbide ingot. In addition, since the silicon carbide gas is sublimated at a uniform rate overall, defects in the silicon carbide ingot and the silicon carbide wafer can be reduced.

[0022] The growth process of the silicon carbide ingot may depend on the particle shape of the silicon carbide powder according to the embodiment. In this case, the particle shape and surface characteristics of the silicon carbide powder can be appropriately adjusted by the crushing process, the grinding process, and the etching process. The particle shape and surface characteristics of the silicon carbide powder according to the embodiment can be determined by the two-dimensional image analysis. When the silicon carbide powder according to the embodiment has a particle circularity, a particle ellipticity, a particle curvature, a particle elongation, a charging space elongation, and a charging space curvature within an appropriate range, the silicon carbide powder has a particle shape and a particle surface that have a positive effect on the growth of the silicon carbide ingot. [Brief description of the drawings]

[0023] [Figure 1] FIG. 2 is a flow chart showing a process for producing silicon carbide powder according to one embodiment. [Diagram 2] FIG. 2 is a flow chart showing a process for producing silicon carbide powder according to one embodiment. [Diagram 3] FIG. 2 is a flow chart showing a process for producing silicon carbide powder according to one embodiment. [Figure 4] FIG. 2 is a flow chart showing a process for producing silicon carbide powder according to one embodiment. [Diagram 5] FIG. 2 is a flow chart showing a process for producing silicon carbide powder according to one embodiment. [Figure 6] FIG. 2 is a flow chart showing a process for producing silicon carbide powder according to one embodiment. [Figure 7] 1A to 1C are cross-sectional views showing a process for growing a silicon carbide ingot. [Figure 8] 1 is a diagram showing a two-dimensional image of particles contained in a silicon carbide powder produced according to Production Example 1. [Figure 9] 1 is a diagram showing a two-dimensional image of particles contained in a silicon carbide powder prepared according to Preparation Example 2. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] The present invention will be described in detail below with reference to the following examples. The examples are not limited to the contents disclosed below, and may be modified in various forms without departing from the spirit and scope of the invention.

[0025] In this specification, when a part "comprises" a certain component, this does not mean that it excludes other components, and it may further include other components, unless otherwise specified to the contrary.

[0026] All numbers and expressions indicating amounts of components, reaction conditions, and the like described in this specification should be understood to be modified in all cases by the term "about," unless otherwise specified.

[0027] First, a method for producing silicon carbide powder according to an embodiment includes a step of preparing a silicon carbide raw material.

[0028] The silicon carbide raw material includes silicon carbide. The silicon carbide raw material may include α-phase silicon carbide and / or β-phase silicon carbide. The silicon carbide raw material may include silicon carbide single crystal and / or silicon carbide polycrystal.

[0029] Furthermore, the silicon carbide raw material may further contain undesirable impurities in addition to silicon carbide.

[0030] The silicon carbide raw material may further contain a carbon-based material such as graphite as an impurity. The carbon-based material may be derived from a graphite crucible or the like. The carbon-based material may be contained in the silicon carbide raw material at a content of about 5% by weight to about 50% by weight. The carbon-based material may be contained in the silicon carbide raw material at a content of about 50% by weight or less. The carbon-based material may be contained in the silicon carbide raw material at a content of about 45% by weight or less. The carbon-based material may be contained in the silicon carbide raw material at a content of about 40% by weight or less. The carbon-based material may be contained in the silicon carbide raw material at a content of about 1% by weight to about 50% by weight. The carbon-based material may be contained in the silicon carbide raw material at a content of about 5% by weight to about 45% by weight. The carbon-based material may be contained in the silicon carbide raw material at a content of about 10% by weight to about 40% by weight. The carbon-based material may be contained in the silicon carbide raw material at a content of about 10% by weight to about 35% by weight.The carbon-based material may be contained in the silicon carbide raw material at a content of about 10% by weight to about 30% by weight.The carbon-based material may be contained in the silicon carbide raw material at a content of about 10% by weight to about 20% by weight.

[0031] The silicon carbide raw material may further include free silicon as the impurity. The free silicon may be derived from a silicon substrate and / or a silicon part. The silicon part may be a part used in a semiconductor device such as a focus ring. The free silicon may be included in the silicon carbide raw material in an amount of about 0.01% by weight to about 10% by weight.

[0032] The silicon carbide raw material may further include metal impurities, which may be at least one selected from the group consisting of lithium, boron, sodium, aluminum, phosphorus, potassium, calcium, titanium, vanadium, chromium, manganese, iron, nickel, copper, zinc, strontium, zirconium, molybdenum, tin, barium, tungsten, and lead.

[0033] The content of the metal impurities may be about 0.1 ppm to 13 ppm. The content of the metal impurities may be about 0.3 ppm to 12 ppm. The content of the metal impurities may be about 0.5 ppm to 8 ppm. The content of the metal impurities may be about 0.8 ppm to 10 ppm. The content of the metal impurities may be about 1 ppm to 6 ppm. The content of the metal impurities may be about 0.1 ppm to 5 ppm. The content of the metal impurities may be about 0.5 ppm to 3 ppm. The content of the metal impurities may be about 0.5 ppm to 2 ppm. The silicon carbide raw material may further include a metal impurity.

[0034] The silicon carbide raw material may further include non-metallic impurities, which may be selected from the group consisting of fluorine, nitrogen, chlorine, and phosphorus.

[0035] The content of the non-metallic impurities may be about 0.01 ppm to 13 ppm. The content of the non-metallic impurities may be about 0.03 ppm to 12 ppm. The content of the non-metallic impurities may be about 0.05 ppm to 8 ppm. The content of the non-metallic impurities may be about 0.08 ppm to 10 ppm. The content of the non-metallic impurities may be about 0.1 ppm to 6 ppm. The content of the non-metallic impurities may be about 0.1 ppm to 5 ppm. The content of the non-metallic impurities may be about 0.5 ppm to 3 ppm. The content of the non-metallic impurities may be about 0.5 ppm to 2 ppm.

[0036] The silicon carbide raw material may have a block shape. The silicon carbide raw material may have a plate shape.

[0037] The silicon carbide feedstock may include at least about 30% by weight of particles having a particle size of at least about 1 mm. The silicon carbide feedstock may include at least about 50% by weight of particles having a particle size of at least about 1 mm. The silicon carbide feedstock may include at least about 70% by weight of particles having a particle size of at least about 1 mm.

[0038] The silicon carbide feedstock may include at least about 30% by weight of particles having a particle size of at least about 10 mm. The silicon carbide feedstock may include at least about 50% by weight of particles having a particle size of at least about 10 mm. The silicon carbide feedstock may include at least about 70% by weight of particles having a particle size of at least about 10 mm.

[0039] Here, assuming a sphere having the same volume as the particle, the spherical diameter is defined as the particle diameter.

[0040] The silicon carbide feedstock may also be derived from a substrate comprising silicon carbide. The silicon carbide feedstock may also be derived from a wafer comprising silicon carbide as a whole. The silicon carbide feedstock may also be derived from a silicon carbide layer deposited on a substrate such as silicon.

[0041] The silicon carbide raw material may be derived from a silicon carbide single crystal ingot. The silicon carbide single crystal ingot may be discarded due to defects occurring during the manufacturing process. Alternatively, the silicon carbide raw material may be derived from a silicon carbide polycrystalline body.

[0042] The silicon carbide raw material may be derived from a silicon carbide sintered body. The silicon carbide sintered body may be formed by sintering silicon carbide powder. The silicon carbide sintered body may be a part included in semiconductor manufacturing equipment.

[0043] The silicon carbide feedstock may be derived from a graphite part including a layer of silicon carbide, the graphite part may include a crucible for forming a silicon carbide ingot, or the like.

[0044] The silicon carbide source material may be derived from a semiconductor device component that includes a silicon carbide layer. The silicon carbide layer may be formed by depositing silicon carbide on a surface of a silicon component or the like by a chemical vapor deposition (CVD) process.

[0045] A method for producing silicon carbide powder according to an embodiment may include cutting the silicon carbide feedstock.

[0046] If the silicon carbide raw material is too large, the silicon carbide raw material can be cut by a wire saw containing diamond abrasive grains, bar cutting, etc. The silicon carbide raw material can be cut so that the length of the silicon carbide raw material is 150 mm.

[0047] A method for producing silicon carbide powder according to an embodiment may include crushing silicon carbide feedstock.

[0048] The step of crushing the silicon carbide raw material may be a step of crushing the silicon carbide raw material into particles having an average particle size of about 100 mm or less. The silicon carbide raw material can be crushed into particles having an average particle size of about 80 mm or less by the crushing step. The silicon carbide raw material can be crushed into particles having an average particle size of about 60 mm or less by the crushing step. The silicon carbide raw material can be crushed into particles having an average particle size of about 50 mm or less by the crushing step. The silicon carbide raw material can be crushed into particles having an average particle size of about 0.1 mm to about 50 mm by the crushing step. The silicon carbide raw material can be crushed into particles having an average particle size of about 1 mm to about 40 mm by the crushing step.

[0049] A jaw crusher, a cone crusher or a gyratory crusher can be used in the crushing step.

[0050] The jaw crusher includes a pair of compression plates between which the silicon carbide feedstock is inserted, and the silicon carbide feedstock is crushed by pressure applied through the compression plates, and the crushed silicon carbide feedstock can be discharged downward by gravity.

[0051] The compression plate may include at least one of steel, stainless steel, manganese-doped steel, chromium-doped steel, nickel-doped steel, molybdenum-doped steel, nitrogen-doped steel, or tungsten carbide. ... tungsten carbide that is in direct contact with the silicon carbide and the feedstock.

[0052] The gyratory crusher comprises a crushing head and a crushing bowl which houses the crushing head. The crushing head has a truncated cone shape and is attached to a shaft. The upper end of the crushing head is fixed to a flexible bearing and the lower end of the crushing head is eccentrically driven in a circular motion. The crushing action is centered around the entire cone, with maximum movement at the bottom. This allows the gyratory crusher to operate continuously, resulting in less stress fluctuations and lower power consumption than the jaw crusher.

[0053] As with the jaw crusher, the crushing head and the crushing ball, which are parts that come into direct contact with the silicon carbide feedstock, can include at least one of steel, stainless steel, manganese-doped steel, chromium-doped steel, nickel-doped steel, molybdenum-doped steel, nitrogen-doped steel, or tungsten carbide. The crushing head and the crushing ball may be made of at least one of steel, stainless steel, manganese-doped steel, chromium-doped steel, nickel-doped steel, molybdenum-doped steel, nitrogen-doped steel, or tungsten carbide. The crushing head and the crushing ball may be coated with the tungsten carbide.

[0054] The cone crusher is a device that crushes the silicon carbide raw material by impact force and compression force. The cone crusher has a structure and crushing motion similar to the gyratory crusher. However, the cone crusher may have a shorter cone. The cone crusher includes an umbrella-shaped cone mantle head attached to a vertical central axis. The eccentric motion of the cone mantle head causes the silicon carbide raw material to be caught in a cone cave bowl, and the silicon carbide raw material is crushed as it descends.

[0055] As with the jaw crusher, the cone mantle head and the cone cave bowl, which are parts that come into direct contact with the silicon carbide feedstock, can include at least one of steel, stainless steel, manganese-doped steel, chromium-doped steel, nickel-doped steel, molybdenum-doped steel, nitrogen-doped steel, or tungsten carbide. The cone mantle head and the cone cave bowl, which are parts that come into direct contact with the silicon carbide feedstock, can be made of at least one of steel, stainless steel, manganese-doped steel, chromium-doped steel, nickel-doped steel, molybdenum-doped steel, nitrogen-doped steel, or tungsten carbide. The cone mantle head and the cone cave bowl, which are parts that come into direct contact with the silicon carbide feedstock, can be coated with the tungsten carbide.

[0056] A method for producing silicon carbide powder according to an embodiment may include milling silicon carbide feedstock.

[0057] The step of crushing the silicon carbide raw material may include a step of breaking the silicon carbide raw material into particles having an average particle size of about 30 mm or less. The silicon carbide raw material may be crushed into particles having an average particle size of about 20 mm or less by the crushing step. The silicon carbide raw material may be crushed into particles having an average particle size of about 15 mm or less by the crushing step. The silicon carbide raw material may be crushed into particles having an average particle size of about 10 mm or less by the crushing step. The silicon carbide raw material may be crushed into particles having an average particle size of about 0.1 mm to about 10 mm by the crushing step. The silicon carbide raw material may be crushed into particles having an average particle size of about 0.1 mm to about 8 mm by the crushing step. The silicon carbide raw material may be crushed into particles having an average particle size of about 0.01 mm to about 6 mm by the crushing step.

[0058] In the pulverizing step, a ball mill, a hammer crusher, a jet mill, or the like can be used.

[0059] The ball mill may include a metal cylinder and balls. The balls and the silicon carbide raw material are disposed in the metal cylinder. When the metal cylinder rotates, the balls and the silicon carbide raw material may be rotated by friction between the balls and the silicon carbide raw material and centrifugal force in the metal cylinder. At this time, the balls and the silicon carbide raw material rise to a certain height in the cylinder and then fall, and the silicon carbide raw material is crushed and polished. Depending on the line speed of the cylinder, the inner diameter of the cylinder, the size of the balls, the material of the balls, and the time of the milling process, the silicon carbide raw material can be crushed into particles having a small particle size.

[0060] The metal cylinder and the ball, which are parts that directly contact the silicon carbide raw material, can include at least one of steel, stainless steel, manganese-doped steel, chromium-doped steel, nickel-doped steel, molybdenum-doped steel, nitrogen-doped steel, or tungsten carbide. The parts of the metal cylinder and the ball that directly contact the silicon carbide raw material may be made of at least one of steel, stainless steel, manganese-doped steel, chromium-doped steel, nickel-doped steel, molybdenum-doped steel, nitrogen-doped steel, or tungsten carbide. The parts of the metal cylinder and the ball that directly contact the silicon carbide and raw material may be coated with the tungsten carbide.

[0061] The hammer crusher includes a crushing chamber and a plurality of hammers. The hammers are attached to a rotor disposed in the crushing chamber. As the hammers rotate in the crushing chamber, they impact the silicon carbide feedstock. This allows the silicon carbide feedstock to be crushed into particles having a small particle size.

[0062] The grinding chamber and the hammer, which are parts that directly contact the silicon carbide raw material, can include at least one of steel, stainless steel, manganese-doped steel, chromium-doped steel, nickel-doped steel, molybdenum-doped steel, nitrogen-doped steel, or tungsten carbide. The grinding chamber and the hammer, which are parts that directly contact the silicon carbide raw material, can be made of at least one of steel, stainless steel, manganese-doped steel, chromium-doped steel, nickel-doped steel, molybdenum-doped steel, nitrogen-doped steel, or tungsten carbide. The grinding chamber and the hammer, which are parts that directly contact the silicon carbide and raw material, can be coated with the tungsten carbide.

[0063] The jet mill includes a grinding chamber and a nozzle. The jet mill grinds the silicon carbide raw material by mutual collision with injection energy from the nozzle due to fluid pressure. The silicon carbide raw material is ground in the grinding chamber until it reaches a desired particle size. The ground particles are collected from the grinding chamber through a classification chamber. The jet mill grinds the silicon carbide raw material by mutual collision with the silicon carbide raw material due to fluid pressure, thereby minimizing contamination of the silicon carbide raw material due to direct contact with other devices.

[0064] The grinding chamber, which is a portion that directly contacts the silicon carbide raw material, can include at least one of steel, stainless steel, manganese-doped steel, chromium-doped steel, nickel-doped steel, molybdenum-doped steel, nitrogen-doped steel, or tungsten carbide. The grinding chamber, which is a portion that directly contacts the silicon carbide raw material, may be made of at least one of steel, stainless steel, manganese-doped steel, chromium-doped steel, nickel-doped steel, molybdenum-doped steel, nitrogen-doped steel, or tungsten carbide. The grinding chamber, which is a portion that directly contacts the silicon carbide and raw material, may be coated with the tungsten carbide.

[0065] The average particle size (D50) of the crushed particles may be about 1 mm to about 15 mm, and the average particle size (D50) of the crushed particles may be about 100 μm to about 3 mm. The average particle size (D50) of the crushed particles may be about 3 mm to about 10 mm, and the average particle size (D50) of the crushed particles may be about 100 μm to about 1 mm. The average particle size (D50) of the crushed particles may be about 1 mm to about 3 mm, and the average particle size (D50) of the crushed particles may be about 300 μm to about 0.8 mm. The average particle size (D50) of the crushed particles may be about 7 mm to about 13 mm, and the average particle size (D50) of the crushed particles may be about 500 μm to about 1.5 mm. The average particle size (D50) of the crushed particles may be about 1 mm to about 3 mm, and the average particle size (D50) of the crushed particles may be about 100 μm to about 800 μm. The average particle size (D50) of the crushed particles may be about 6 mm to about 10 mm, and the average particle size (D50) of the crushed particles may be about 1 mm to about 3 mm. The average particle size (D50) of the crushed particles may be about 4 mm to about 8 mm, and the average particle size (D50) of the crushed particles may be about 800 μm to about 2 mm. Since the crushing process and the pulverization process are performed to have an average particle size (D50) in the above range, the silicon carbide powder according to the embodiment can be manufactured to have a desired particle size and a desired shape.

[0066] The pulverization step can be carried out by a ball mill step. In the ball mill step, the diameter of the balls may be about 5 mm to about 50 mm. The diameter of the balls may be about 10 mm to about 40 mm.

[0067] In the ball milling step, the rotation speed of the cylinder may be about 10 rpm to about 40 rpm.In the ball milling step, the rotation speed of the cylinder may be about 15 rpm to about 35 rpm.

[0068] In the ball milling step, steel balls can be used. The ball milling step can be carried out for about 10 minutes to about 30 minutes.

[0069] In order to appropriately adjust the grain size and grain shape of the silicon carbide powder according to the embodiment, the diameter of the ball in the ball mill process, the rotation speed of the cylinder, and the time of the ball mill process can be appropriately controlled.

[0070] The method for producing silicon carbide powder according to the embodiment may further include removing iron by magnetic force.

[0071] The iron component removing step may be a step of removing iron adsorbed to the silicon carbide raw material in the crushing and pulverizing step.

[0072] In the step of removing the iron components, the iron can be removed using a rotary metal detector.

[0073] The rotation speed of the rotary metal detector may be about 100 rpm to about 800 rpm, and the output of the electromagnet included in the rotary metal detector may be about 0.5 kW to about 3 kW. Alternatively, the rotation speed of the rotary metal detector may be about 800 rpm to about 1700 rpm, and the output of the electromagnet included in the rotary metal detector may be about 3 kW to about 5 kW.

[0074] The content of iron contained in the silicon carbide raw material from which the iron components have been removed may be about 1 ppm or less. The content of iron contained in the silicon carbide raw material from which the iron components have been removed may be about 0.5 ppm or less. The content of iron contained in the silicon carbide raw material from which the iron components have been removed may be about 0.3 ppm or less. The content of iron contained in the silicon carbide raw material from which the iron components have been removed may be about 0.1 ppm or less.

[0075] A method for producing silicon carbide powder according to an embodiment includes removing the carbon-based material.

[0076] The step of removing the carbon-based material may include physically removing the carbon-based material.

[0077] The step of physically removing the carbon-based material may include a steel wire shot process. The wire used in the steel wire shot may be made of, but is not limited to, carbon steel, stainless steel, aluminum, zinc, nickel, copper, or an alloy thereof. The diameter of the wire may be about 0.2 mm to about 0.8 mm. The diameter of the wire saw may be about 0.4 mm to about 0.6 mm.

[0078] The rotation speed of the wire may be about 1000 rpm to about 5000 rpm.

[0079] Also, the step of physically removing the carbon-based material may include a blasting process such as sandblasting or short blasting. The blasting process may be a process of spraying fine particles onto the carbon-based material such as graphite to remove the carbon-based material. That is, since the carbon-based material has a lower hardness than the silicon carbide, it can be easily removed by spraying fine particles at an appropriate pressure.

[0080] The step of physically removing the carbon-based material may include a separation process based on density difference, such as centrifugation. The crushed and / or pulverized silicon carbide raw material may be separated based on the density difference between the carbon-based material and the silicon carbide. That is, since the density of silicon carbide is greater than that of graphite, the carbon-based material may be easily removed by density gradient centrifugation.

[0081] After physically removing the carbon-based material, the source material may have a carbon-based material content of about 5 wt% or less. After removing the carbon-based material, the source material may have a carbon-based material content of about 3 wt% or less. After removing the carbon-based material, the source material may have a carbon-based material content of about 1 wt% or less.

[0082] Additionally, removing the carbon-based material may include chemically removing the carbon-based material.

[0083] Chemically removing the carbon-based material may include oxidizing the carbon-based material.

[0084] After the carbonaceous material contained in the raw material is sufficiently removed, the raw material is heat-treated in an oxygen or air atmosphere, where the oxidation heat treatment temperature may be about 1000° C. to about 1200° C., and the heat treatment time may be about 12 hours to about 48 hours.

[0085] Since the source material is heat-treated within the above-mentioned time and temperature range, carbonaceous materials contained in the source material can be effectively removed. Also, since the source material is heat-treated within the above-mentioned time and temperature range, the generation of by-products such as silicon oxide in the source material can be minimized.

[0086] The method for producing silicon carbide powder according to the embodiment includes a step of classifying the silicon carbide raw material. The classifying step may classify the silicon carbide raw material granulated through the crushing process and the pulverizing process.

[0087] The granulated silicon carbide raw material can be classified according to a mesh of a desired size.

[0088] The classification step can be carried out using a Twist Screen, which is a vibration type classification device.

[0089] The twist screen can use a tapping ball made of silicon having a diameter of 10 mm to 80 mm, 15 mm to 70 mm, or 20 mm to 60 mm. The twist screen can be performed under vibration conditions of about 1000 times / min to 3000 times / min for about 10 minutes to about 100 minutes.

[0090] The granulated silicon carbide feedstock may be fed into the twist screen at a constant rate.

[0091] The particle size (D50) of the granulated silicon carbide raw material may be about 10 μm to about 10000 μm. The particle size (D50) of the granulated silicon carbide raw material may be about 100 μm to about 6000 μm. The particle size (D50) of the granulated silicon carbide raw material may be about 60 μm to about 5000 μm. The particle size (D50) of the granulated silicon carbide raw material may be about 100 μm to about 4000 μm. The particle size (D50) of the granulated silicon carbide raw material may be about 150 μm to about 400 μm. The particle size (D50) of the granulated silicon carbide raw material may be about 300 μm to about 800 μm. The particle size (D50) of the granulated silicon carbide raw material may be about 500 μm to about 1000 μm. The particle size (D50) of the granulated silicon carbide raw material may be about 700 μm to about 2000 μm.The particle size (D50) of the granulated silicon carbide raw material may be about 1000 μm to about 3000 μm.

[0092] A method for producing silicon carbide powder according to an embodiment may include wet etching the silicon carbide raw material.

[0093] The wet etching step is performed using an etchant. The silicon carbide raw material that has been subjected to the crushing and pulverizing process may be subjected to the wet etching step.

[0094] The etching solution may include water and an acid, and the acid may be at least one selected from the group consisting of hydrofluoric acid, nitric acid, hydrochloric acid, and sulfuric acid.

[0095] The etching solution may include deionized water, hydrofluoric acid, and nitric acid.

[0096] The hydrofluoric acid may be contained in the etching solution at a content of about 10 parts by weight to about 50 parts by weight based on 100 parts by weight of the deionized water. The hydrofluoric acid may be contained in the etching solution at a content of about 15 parts by weight to about 45 parts by weight based on 100 parts by weight of the deionized water. The hydrofluoric acid may be contained in the etching solution at a content of about 20 parts by weight to about 40 parts by weight based on 100 parts by weight of the deionized water.

[0097] The nitric acid may be contained in the etching solution at a content of about 10 parts by weight to about 50 parts by weight based on 100 parts by weight of the deionized water. The nitric acid may be contained in the etching solution at a content of about 15 parts by weight to about 45 parts by weight based on 100 parts by weight of the deionized water. The nitric acid may be contained in the etching solution at a content of about 20 parts by weight to about 40 parts by weight based on 100 parts by weight of the deionized water.

[0098] The etching container may be filled with the etching solution. In this case, the etching container may be filled with the etching solution at about 10 vol% to about 20 vol% based on the total volume of the etching container. The etching container may be filled with the etching solution at about 12 vol% to about 18 vol% based on the total volume of the etching container. Also, the silicon carbide raw material may be filled in the etching container at about 10 vol% to about 30 vol% based on the total volume of the etching container. The silicon carbide raw material may be filled in the etching container at about 15 vol% to about 25 vol% based on the total volume of the etching container.

[0099] The silicon carbide raw material may be wet-etched with the etching solution. That is, the surface of the silicon carbide raw material is etched with the etching solution, and impurities remaining on the surface of the silicon carbide raw material can be removed by the etching solution.

[0100] The wet etching step can be performed according to the following process.

[0101] First, the etching vessel and the silicon carbide raw material can be dried. The etching vessel and the silicon carbide raw material can be dried with hot air at about 50° C. to about 150° C. for about 10 minutes to about 1 hour.

[0102] The silicon carbide feedstock is then placed in the etching chamber.

[0103] Thereafter, the etching solution is poured into the etching vessel in which the silicon carbide raw material is placed.

[0104] The etching solution is introduced as follows.

[0105] First, deionized water is charged into the etching vessel in which the silicon carbide raw material is placed.

[0106] Thereafter, hydrofluoric acid is added to the etching vessel containing the deionized water.

[0107] Thereafter, nitric acid is added to the etching vessel containing the hydrofluoric acid.

[0108] Thereafter, the etching container containing the etching solution is sealed with a lid, and the silicon carbide raw material and the etching solution placed inside the etching container are stirred at a speed of about 50 rpm to about 500 rpm for a period of about 30 minutes to about 2 hours.

[0109] Then, the etching solution is drained, and the silicon carbide raw material that has been subjected to the wet etching process is precipitated and neutralized several times in deionized water. At this time, the neutralization process of the silicon carbide raw material that has been subjected to the wet etching process is completed based on the content and / or pH of hydrofluoric acid contained in the wastewater that is drained after precipitation. When the pH of the wastewater is 6.8 to 7.2, the neutralization process is completed.

[0110] A method for producing silicon carbide powder according to an embodiment may include dry etching the silicon carbide raw material.

[0111] The dry etching step can be performed by injecting an etching gas onto the silicon carbide raw material.

[0112] The etching gas may include chlorine gas, and the etching gas may further include an inert gas, such as argon, as a carrier gas.

[0113] The dry etching process can be carried out as follows.

[0114] First, a dry etching furnace is prepared. The dry etching furnace may be made of graphite and may be heated to a temperature of about 2000° C. or more. The dry etching furnace may be sealed from the outside, and the inside of the dry etching furnace may be depressurized to about 5 torr or less.

[0115] The silicon carbide feedstock is placed in the dry etching furnace.

[0116] The dry etching furnace is then heated to a temperature of about 1800°C to about 2200°C.

[0117] Thereafter, the pressure inside the dry etching furnace is reduced to about 1 torr to about 30 torr.The pressure inside the dry etching furnace is reduced to about 1 torr to about 10 torr.The pressure inside the dry etching furnace is reduced to about 1 torr to about 8 torr.

[0118] Then, the etching gas is introduced into the dry etching furnace. The etching gas can be convected in the dry etching furnace due to the temperature difference between the lower and upper parts of the dry etching furnace. That is, the temperature of the lower part of the dry etching furnace is about 50°C to about 100°C higher than the temperature of the upper part of the dry etching furnace, and the etching gas in the lower part of the dry etching furnace can move to the upper part of the dry etching furnace and dry etch the surface of the silicon carbide raw material. The time that the etching gas is retained in the dry etching furnace may be about 24 hours to about 96 hours.

[0119] Thereafter, the etching gas may be removed by a wet scrubber, and the inside of the dry etching furnace may be pressurized to about 600 torr to about 780 torr.

[0120] The dry etching process may further include a heat treatment process and an oxide film removing process.

[0121] The dry-etched silicon carbide particles may be heat-treated in the dry etching furnace in an oxygen-containing atmosphere at a temperature of about 700°C to about 1300°C. The dry-etched silicon carbide particles may be heat-treated in the dry etching furnace in an oxygen-containing atmosphere at a temperature of about 800°C to about 1200°C. The dry-etched silicon carbide particles may be heat-treated in the dry etching furnace in an oxygen-containing atmosphere at a temperature of about 900°C to about 1100°C. The heat treatment time may be about 10 minutes to about 2 hours. The heat treatment time may be about 20 minutes to about 1 hour.

[0122] The heat treatment can easily remove chlorine remaining on the surfaces of the dry-etched silicon carbide particles.

[0123] The oxide film removal process can be performed by a wet etching process.

[0124] The heat-treated silicon carbide raw material is charged into an etching vessel, and deionized water and hydrofluoric acid are further charged into the etching vessel.

[0125] Thereafter, the silicon carbide raw material and the etching solution in the etching container are stirred, so that the oxide film formed on the surface of the silicon carbide raw material can be removed.

[0126] The silicon carbide raw material from which the oxide film has been removed is neutralized with deionized water.

[0127] The method for producing silicon carbide powder according to the embodiment may include washing the silicon carbide feedstock.

[0128] The cleaning step can be carried out using a cleaning liquid containing at least one selected from the group consisting of hydrofluoric acid, distilled water, ultrapure water, and the like.

[0129] The cleaning process may include a first cleaning step, a first hydrofluoric acid treatment step, a second cleaning step, a second hydrofluoric acid treatment step, and a third cleaning step.

[0130] The first cleaning step can be performed for 1 minute to 300 minutes using distilled water, ultrapure water, or pure water. For example, the first cleaning step can be performed for about 1 minute to about 250 minutes, about 1 minute to about 200 minutes, about 3 minutes to about 150 minutes, about 10 minutes to about 100 minutes, about 15 minutes to about 80 minutes, about 20 minutes to about 60 minutes, or about 20 minutes to about 40 minutes.

[0131] Then, the first hydrofluoric acid treatment step is a step of cleaning the silicon carbide raw material using a cleaning solution containing hydrofluoric acid. The silicon carbide raw material can be stirred in the cleaning solution for about 1 minute to about 300 minutes, about 1 minute to about 250 minutes, about 1 minute to about 200 minutes, about 3 minutes to about 150 minutes, about 10 minutes to about 100 minutes, about 15 minutes to about 80 minutes, about 20 minutes to about 60 minutes, or about 20 minutes to about 40 minutes. Then, the silicon carbide raw material may be precipitated in the cleaning solution. The silicon carbide raw material may be precipitated in the cleaning solution for about 1 minute to about 300 minutes, about 1 minute to about 250 minutes, about 1 minute to about 200 minutes, about 3 minutes to about 150 minutes, about 10 minutes to about 100 minutes, about 15 minutes to about 80 minutes, about 20 minutes to about 60 minutes, or about 20 minutes to about 40 minutes.

[0132] The second cleaning step can be performed for 1 minute to 300 minutes using distilled water, ultrapure water, or pure water. For example, the second cleaning step can be performed for about 1 minute to about 250 minutes, about 1 minute to about 200 minutes, about 3 minutes to about 150 minutes, about 10 minutes to about 100 minutes, about 15 minutes to about 80 minutes, about 20 minutes to about 60 minutes, or about 20 minutes to about 40 minutes.

[0133] Thereafter, the second hydrofluoric acid treatment step is a step of cleaning the silicon carbide raw material using a cleaning solution containing hydrofluoric acid. The silicon carbide raw material can be stirred in the cleaning solution for about 1 minute to about 300 minutes, about 1 minute to about 250 minutes, about 1 minute to about 200 minutes, about 3 minutes to about 150 minutes, about 10 minutes to about 100 minutes, about 15 minutes to about 80 minutes, about 20 minutes to about 60 minutes, or about 20 minutes to about 40 minutes. Then, the silicon carbide raw material may be precipitated in the cleaning solution. The silicon carbide raw material may be precipitated in the cleaning solution for about 1 minute to about 300 minutes, about 1 minute to about 250 minutes, about 1 minute to about 200 minutes, about 3 minutes to about 150 minutes, about 10 minutes to about 100 minutes, about 15 minutes to about 80 minutes, about 20 minutes to about 60 minutes, or about 20 minutes to about 40 minutes.

[0134] The tertiary cleaning step can be performed for 1 minute to 300 minutes using distilled water, ultrapure water, or pure water. For example, the tertiary cleaning step can be performed for about 1 minute to about 250 minutes, about 1 minute to about 200 minutes, about 3 minutes to about 150 minutes, about 10 minutes to about 100 minutes, about 15 minutes to about 80 minutes, about 20 minutes to about 60 minutes, or about 20 minutes to about 40 minutes.

[0135] By performing the graphite removing step, the iron component removing step, the wet etching step, the dry etching step, and the cleaning step, the silicon carbide powder according to the embodiment can have very high purity.

[0136] Referring to FIG. 1, the silicon carbide powder according to one embodiment can be manufactured by the following process.

[0137] First, the silicon carbide raw material is crushed in the crushing step (S10).

[0138] Thereafter, the carbon-based material removal step removes carbon-based materials such as graphite contained in the silicon carbide raw material (S20).

[0139] Thereafter, the silicon carbide raw material from which the carbon-based material has been removed is pulverized by the pulverization step (S30).

[0140] Thereafter, the pulverized silicon carbide raw material is etched by a wet etching process (S40). This allows the impurities attached to the surface of the pulverized silicon carbide raw material to be efficiently removed. In particular, the carbon-based material remaining in the pulverized silicon carbide raw material floats in the etching solution and can react with hydrofluoric acid and the like contained in the etching solution. This allows the wet etching process to efficiently remove not only metal impurities but also the carbon-based material.

[0141] Thereafter, the wet-etched silicon carbide raw material is etched by a dry etching process (S50).

[0142] Thereafter, the dry-etched silicon carbide raw material undergoes a cleaning process (S60).

[0143] The washed silicon carbide feedstock can then be classified to a desired particle size (S70).

[0144] Referring to FIG. 2, the silicon carbide powder according to one embodiment can be manufactured by the following process.

[0145] In this embodiment, the process is substantially the same as that in FIG. 1, but a carbonaceous material removing step can be carried out before the crushing step (S1).

[0146] When the silicon carbide raw material contains a large amount of carbon as an impurity, the carbon-based material removing process may be performed first. For example, when the silicon carbide raw material contains a high proportion of graphite components, such as silicon carbide-coated graphite parts, the carbon-based material removing process may be performed first.

[0147] Since the carbon-based material is removed first (S1) and then the crushing step (S10) is performed, the carbon-based material contained in the silicon carbide raw material can be efficiently removed.

[0148] Therefore, the method for producing silicon carbide powder according to the present embodiment can provide high-purity silicon carbide powder by using silicon carbide raw material containing a high content of carbon-based materials.

[0149] Referring to FIG. 3, the method for producing silicon carbide powder according to an embodiment may be performed through the following process.

[0150] In this embodiment, the process is substantially the same as that of FIG. 1, but the carbonaceous material removing step may be omitted.

[0151] When the silicon carbide raw material does not contain or contains a very low content of carbon-based materials such as graphite, the carbon-based material removal process may be omitted. For example, the silicon carbide raw material may contain silicon carbide in an amount of about 95% by weight or more, such as a single crystal silicon carbide ingot, polycrystalline silicon carbide, or sintered silicon carbide. In such a case, a small amount of carbon-based materials is removed in the wet etching process, etc., and a high-purity silicon carbide powder can be obtained without an additional process.

[0152] Referring to FIGS. 4 to 6, the silicon carbide powder according to an embodiment can be manufactured through the following process.

[0153] In this embodiment, the process is substantially the same as that of Fig. 1, Fig. 2 or Fig. 3, but the classification process (S31) can be performed immediately after the pulverization process (S30). That is, the pulverized silicon carbide raw material can be classified into a desired particle size through the classification process immediately after the pulverization process. The classified silicon carbide raw material can be subjected to the wet etching process, the dry etching process and the cleaning process.

[0154] In this embodiment, the silicon carbide raw material is classified into particles of uniform particle size, and then the wet etching process and the dry etching process are performed, so that the surface of the silicon carbide raw material may be etched uniformly as a whole. In particular, since the silicon carbide raw material is classified into particles of uniform particle size, the spaces between the silicon carbide raw material particles can also be formed uniformly. As a result, the etching gas can be uniformly permeated into the spaces between the silicon carbide raw material particles, and the dry etching process can uniformly etch the silicon carbide raw material as a whole.

[0155] Therefore, the method for producing silicon carbide powder according to the present embodiment can uniformly adjust the contents of carbon, silicon, and oxygen contained on the surface as a whole.

[0156] The purity of the silicon carbide powder according to the embodiment may be about 99.99% or more. The purity of the silicon carbide powder according to the embodiment may be about 99.9 ...

[0157] The silicon carbide powder according to the embodiment may contain about 1 ppm or less, about 0.8 ppm or less, about 0.7 ppm or less, about 0.1 to about 0.7 ppm, or about 0.1 to about 0.6 ppm of impurities selected from the group consisting of lithium, sodium, magnesium, aluminum, potassium, calcium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, or molybdenum.

[0158] The particle size (D50) of the silicon carbide powder according to the embodiment may be about 10 μm to about 10000 μm. The particle size (D50) of the silicon carbide powder according to the embodiment may be about 100 μm to about 6000 μm. The particle size (D50) of the silicon carbide powder according to the embodiment may be about 60 μm to about 5000 μm. The particle size (D50) of the silicon carbide powder according to the embodiment may be about 100 μm to about 4000 μm. The particle size (D50) of the silicon carbide powder according to the embodiment may be about 150 μm to about 400 μm. The particle size (D50) of the silicon carbide powder according to the embodiment may be about 300 μm to about 800 μm. The particle size (D50) of the silicon carbide powder according to the embodiment may be about 500 μm to about 1000 μm. The particle size (D50) of the silicon carbide powder according to the embodiment may be about 700 μm to about 2000 μm.The particle size (D50) of the silicon carbide powder according to the embodiment may be about 1000 μm to about 3000 μm.

[0159] The silicon carbide powder according to the embodiment contains carbon and oxygen in an appropriate content ratio on the surface, so that when silicon carbide ingots and silicon carbide wafers are manufactured using the silicon carbide powder according to the embodiment, the oxygen content is appropriate, and therefore defects in the silicon carbide ingots and silicon carbide wafers can be reduced.

[0160] In particular, since the silicon carbide powder contains carbon and oxygen in an appropriate content ratio on the surface, the oxygen can be easily removed by reacting with the carbon during the initial heat treatment step, and thus defects during the growth of the silicon carbide ingot can be minimized by removing the surface oxygen of the silicon carbide powder during the initial heat treatment step.

[0161] In addition, the oxygen reacts with the carbon and is removed as carbon dioxide, etc., and the amount of carbon consumed during the removal of the oxygen may be reduced. Therefore, even after the oxygen is removed together with the carbon, the ratio of the silicon and the carbon is appropriate as a whole in the silicon carbide powder. Therefore, the silicon carbide powder according to the embodiment may minimize defects that may occur due to variations in the carbon and silicon contents.

[0162] In addition, the silicon carbide powder according to the embodiment contains silicon and oxygen at an appropriate content ratio on the surface. This allows the silicon carbide powder according to the embodiment to be effectively protected from external impurities. That is, the silicon carbide powder according to the embodiment includes a protective film containing oxygen on the surface, and can be effectively protected from external chemical impact.

[0163] In addition, the silicon carbide powder according to the embodiment may contain the fluorine component as a by-product during the manufacturing process. At this time, since the method for manufacturing the silicon carbide powder according to the embodiment includes the wet etching process, the dry etching process, and the cleaning process, the content of the fluorine component is low. In addition, since the process for manufacturing the silicon carbide ingot according to the embodiment includes an initial heat treatment process of the silicon carbide powder according to the embodiment, the fluorine component can be efficiently removed. That is, the fluorine component can be easily removed by vaporization in the initial heat treatment process.

[0164] Silicon carbide powder according to the embodiments has very high purity and can produce silicon carbide wafers with improved performance.

[0165] The silicon carbide powder according to the embodiment can be analyzed for particle shape by two-dimensional image analysis.

[0166] The silicon carbide powder according to the embodiment may be sampled as appropriate and the two-dimensional image analysis may be performed. For example, the silicon carbide powder according to the embodiment may be sampled about 5 to about 100 times, about 0.1 g to about 10 g each time, and the two-dimensional image analysis may be performed for each sample. In this case, measured values ​​derived by the two-dimensional image analysis may be obtained, and the characteristics of the silicon carbide powder according to the embodiment may be defined as the average value of the measured values.

[0167] The sampled silicon carbide powder is sprinkled on a background, which may have a hue that is visually distinct from the silicon carbide powder, and each of the sprinkled silicon carbide particles is spaced apart from one another so as not to overlap one another.

[0168] Particles contained in the silicon carbide powder according to the embodiment are photographed by an optical microscope to obtain a two-dimensional image of the particles.

[0169] The two-dimensional image of the silicon carbide powder according to the embodiment can then be analyzed by image analysis software, such as the iSolution series from Image & Microscope Technology (IMT).

[0170] When the silicon carbide powder according to the embodiment is analyzed by the two-dimensional image analysis, the average area of ​​the particles contained in the silicon carbide powder is about 50,000 μm 2 ~5 million μm 2 When the silicon carbide powder according to the embodiment is analyzed by the two-dimensional image analysis, the average area of ​​the particles contained in the silicon carbide powder is about 50,000 μm 2 ~100,000μm 2 When the silicon carbide powder according to the embodiment is analyzed by the two-dimensional image analysis, the average area of ​​the particles contained in the silicon carbide powder is about 150,000 μm 2 ~250,000μm 2 When the silicon carbide powder according to the embodiment is analyzed by the two-dimensional image analysis, the average area of ​​the particles contained in the silicon carbide powder is about 1 million μm 2 ~2 million μm 2 When the silicon carbide powder according to the embodiment is analyzed by the two-dimensional image analysis, the average area of ​​the particles contained in the silicon carbide powder is about 2.5 million μm 2 ~3.5 million μm 2 When the silicon carbide powder according to the embodiment is analyzed by the two-dimensional image analysis, the average area of ​​the particles contained in the silicon carbide powder is about 3.5 million μm 2 ~5 million μm 2 may be also possible.

[0171] When the silicon carbide powder according to the embodiment is analyzed by the two-dimensional image analysis, the average perimeter of the particles contained in the silicon carbide powder may be about 500 μm to about 10 mm. When the silicon carbide powder according to the embodiment is analyzed by the two-dimensional image analysis, the average perimeter of the particles contained in the silicon carbide powder may be about 500 μm to about 1.5 mm. When the silicon carbide powder according to the embodiment is analyzed by the two-dimensional image analysis, the average perimeter of the particles contained in the silicon carbide powder may be about 1.5 mm to about 2.5 mm. When the silicon carbide powder according to the embodiment is analyzed by the two-dimensional image analysis, the average perimeter of the particles contained in the silicon carbide powder may be about 4 mm to about 6 mm. When the silicon carbide powder according to the embodiment is analyzed by the two-dimensional image analysis, the average perimeter of the particles contained in the silicon carbide powder may be about 7 mm to about 10 mm.

[0172] When the silicon carbide powder according to the embodiment is analyzed by the two-dimensional image analysis, the average equivalent circular diameter of the particles contained in the silicon carbide powder may be about 150 μm to about 3 mm. The equivalent circular diameter is calculated based on the area. That is, the equivalent circular diameter may mean the diameter of a circle assumed to have the same area as the area. When the silicon carbide powder according to the embodiment is analyzed by the two-dimensional image analysis, the average equivalent circular diameter of the particles contained in the silicon carbide powder may be about 150 μm to about 300 μm. When the silicon carbide powder according to the embodiment is analyzed by the two-dimensional image analysis, the average equivalent circular diameter of the particles contained in the silicon carbide powder may be about 300 μm to about 700 μm. When the silicon carbide powder according to the embodiment is analyzed by the two-dimensional image analysis, the average equivalent circular diameter of the particles contained in the silicon carbide powder may be about 1000 μm to about 1500 μm. When the silicon carbide powder according to the embodiment is analyzed by the two-dimensional image analysis, the average equivalent circular diameter of the particles contained in the silicon carbide powder may be about 1500 μm to about 2300 μm.When the silicon carbide powder according to the embodiment is analyzed by the two-dimensional image analysis, the average equivalent circular diameter of the particles contained in the silicon carbide powder may be about 2000 μm to about 2500 μm.

[0173] When the silicon carbide powder according to the embodiment is analyzed by the two-dimensional image analysis, the average maximum elliptical diameter of the particles contained in the silicon carbide powder may be about 300 μm to about 3500 μm. When the silicon carbide powder according to the embodiment is analyzed by the two-dimensional image analysis, the average maximum elliptical diameter of the particles contained in the silicon carbide powder may be about 300 μm to about 400 μm. When the silicon carbide powder according to the embodiment is analyzed by the two-dimensional image analysis, the average maximum elliptical diameter of the particles contained in the silicon carbide powder may be about 600 μm to about 750 μm. When the silicon carbide powder according to the embodiment is analyzed by the two-dimensional image analysis, the average maximum elliptical diameter of the particles contained in the silicon carbide powder may be about 1000 μm to about 2000 μm. When the silicon carbide powder according to the embodiment is analyzed by the two-dimensional image analysis, the average maximum elliptical diameter of the particles contained in the silicon carbide powder may be about 2500 μm to about 3500 μm.When the silicon carbide powder according to the embodiment is analyzed by the two-dimensional image analysis, the average maximum elliptical diameter of the particles contained in the silicon carbide powder may be about 550 μm to about 800 μm.

[0174] When the silicon carbide powder according to the embodiment is analyzed by the two-dimensional image analysis, the average minimum elliptical diameter of the particles contained in the silicon carbide powder may be about 150 μm to about 2500 μm. When the silicon carbide powder according to the embodiment is analyzed by the two-dimensional image analysis, the average minimum elliptical diameter of the particles contained in the silicon carbide powder may be about 150 μm to about 250 μm. When the silicon carbide powder according to the embodiment is analyzed by the two-dimensional image analysis, the average minimum elliptical diameter of the particles contained in the silicon carbide powder may be about 300 μm to about 500 μm. When the silicon carbide powder according to the embodiment is analyzed by the two-dimensional image analysis, the average minimum elliptical diameter of the particles contained in the silicon carbide powder may be about 850 μm to about 1300 μm. When the silicon carbide powder according to the embodiment is analyzed by the two-dimensional image analysis, the average minimum elliptical diameter of the particles contained in the silicon carbide powder may be about 1300 μm to about 1900 μm.When the silicon carbide powder according to the embodiment is analyzed by the two-dimensional image analysis, the average minimum elliptical diameter of the particles contained in the silicon carbide powder may be about 1700 μm to about 2500 μm.

[0175] When the silicon carbide powder according to the embodiment is analyzed by the two-dimensional image analysis, the average maximum length of the particles contained in the silicon carbide powder may be about 250 μm to about 3000 μm. Here, the maximum length may mean the length in the longest direction in the two-dimensional image of each particle. When the silicon carbide powder according to the embodiment is analyzed by the two-dimensional image analysis, the average maximum length of the particles contained in the silicon carbide powder may be about 250 μm to about 400 μm. When the silicon carbide powder according to the embodiment is analyzed by the two-dimensional image analysis, the average maximum length of the particles contained in the silicon carbide powder may be about 500 μm to about 800 μm. When the silicon carbide powder according to the embodiment is analyzed by the two-dimensional image analysis, the average maximum length of the particles contained in the silicon carbide powder may be about 1300 μm to about 1800 μm. When the silicon carbide powder according to the embodiment is analyzed by the two-dimensional image analysis, the average maximum length of the particles contained in the silicon carbide powder may be about 1700 μm to about 2300 μm.When the silicon carbide powder according to the embodiment is analyzed by the two-dimensional image analysis, the average maximum length of the particles contained in the silicon carbide powder may be about 2200 μm to about 3000 μm.

[0176] When the silicon carbide powder according to the embodiment is analyzed by the two-dimensional image analysis, the average maximum frame diameter of the particles included in the silicon carbide powder according to the embodiment may be about 300 μm to about 3500 μm. The captured image of the particles may be measured with a virtual vernier caliper while rotating. At this time, the maximum frame diameter may mean the largest of the measured widths. When the silicon carbide powder according to the embodiment is analyzed by the two-dimensional image analysis, the average maximum frame diameter of the particles included in the silicon carbide powder according to the embodiment may be about 300 μm to about 450 μm. When the silicon carbide powder according to the embodiment is analyzed by the two-dimensional image analysis, the average maximum frame diameter of the particles included in the silicon carbide powder according to the embodiment may be about 500 μm to about 900 μm. When the silicon carbide powder according to the embodiment is analyzed by the two-dimensional image analysis, the average maximum frame diameter of the particles included in the silicon carbide powder according to the embodiment may be about 1300 μm to about 2000 μm. When the silicon carbide powder according to the embodiment is analyzed by the two-dimensional image analysis, the average maximum frame diameter of the particles contained in the silicon carbide powder according to the embodiment may be about 2200 μm to about 2600 μm.When the silicon carbide powder according to the embodiment is analyzed by the two-dimensional image analysis, the average maximum frame diameter of the particles contained in the silicon carbide powder according to the embodiment may be about 2700 μm to about 3500 μm.

[0177] When the silicon carbide powder according to the embodiment is analyzed by the two-dimensional image analysis, the average minimum frame diameter of the particles included in the silicon carbide powder according to the embodiment may be about 150 μm to about 2200 μm. The captured image of the particles may be measured with a virtual Vernier caliper while rotating. At this time, the minimum frame diameter may mean the smallest of the measured widths. When the silicon carbide powder according to the embodiment is analyzed by the two-dimensional image analysis, the average minimum frame diameter of the particles included in the silicon carbide powder according to the embodiment may be about 150 μm to about 280 μm. When the silicon carbide powder according to the embodiment is analyzed by the two-dimensional image analysis, the average minimum frame diameter of the particles included in the silicon carbide powder according to the embodiment may be about 350 μm to about 450 μm. When the silicon carbide powder according to the embodiment is analyzed by the two-dimensional image analysis, the average minimum frame diameter of the particles included in the silicon carbide powder according to the embodiment may be about 750 μm to about 1250 μm. When the silicon carbide powder according to the embodiment is analyzed by the two-dimensional image analysis, the average minimum frame diameter of the particles contained in the silicon carbide powder according to the embodiment may be about 1300 μm to about 1800 μm.When the silicon carbide powder according to the embodiment is analyzed by the two-dimensional image analysis, the average minimum frame diameter of the particles contained in the silicon carbide powder according to the embodiment may be about 1800 μm to about 2200 μm.

[0178] When the silicon carbide powder according to the embodiment is analyzed by the two-dimensional image analysis, the average minimum frame diameter of the particles included in the silicon carbide powder according to the embodiment may be about 250 μm to about 2700 μm. The captured particle image may be measured with a virtual Vernier caliper while rotating. In this case, the mid-frame diameter may mean the average of the measured widths. When the silicon carbide powder according to the embodiment is analyzed by the two-dimensional image analysis, the average minimum frame diameter of the particles included in the silicon carbide powder according to the embodiment may be about 250 μm to about 350 μm. When the silicon carbide powder according to the embodiment is analyzed by the two-dimensional image analysis, the average minimum frame diameter of the particles included in the silicon carbide powder according to the embodiment may be about 400 μm to about 600 μm. When the silicon carbide powder according to the embodiment is analyzed by the two-dimensional image analysis, the average minimum frame diameter of the particles included in the silicon carbide powder according to the embodiment may be about 1250 μm to about 1700 μm. When the silicon carbide powder according to the embodiment is analyzed by the two-dimensional image analysis, the average minimum frame diameter of the particles contained in the silicon carbide powder according to the embodiment may be about 1800 μm to about 2200 μm.When the silicon carbide powder according to the embodiment is analyzed by the two-dimensional image analysis, the average minimum frame diameter of the particles contained in the silicon carbide powder according to the embodiment may be about 2300 μm to about 2700 μm.

[0179] When the silicon carbide powder according to the embodiment is analyzed by the two-dimensional image analysis, the average convex hull of the particles contained in the silicon carbide powder according to the embodiment may be about 700 μm to about 10,000 μm. When the silicon carbide powder according to the embodiment is analyzed by the two-dimensional image analysis, the average convex hull of the particles contained in the silicon carbide powder according to the embodiment may be about 700 μm to about 1,300 μm. When the silicon carbide powder according to the embodiment is analyzed by the two-dimensional image analysis, the average convex hull of the particles contained in the silicon carbide powder according to the embodiment may be about 1,600 μm to about 2,200 μm. When the silicon carbide powder according to the embodiment is analyzed by the two-dimensional image analysis, the average convex hull of the particles contained in the silicon carbide powder according to the embodiment may be about 4,000 μm to about 5,000 μm. When the silicon carbide powder according to the embodiment is analyzed by the two-dimensional image analysis, the average convex hull of the particles contained in the silicon carbide powder according to the embodiment may be about 6000 μm to about 7000 μm.When the silicon carbide powder according to the embodiment is analyzed by the two-dimensional image analysis, the average convex hull of the particles contained in the silicon carbide powder according to the embodiment may be about 7000 μm to about 9000 μm.

[0180] When the silicon carbide powder according to the embodiment is analyzed by the two-dimensional image analysis, the average particle circularity of the particles contained in the silicon carbide powder according to the embodiment may be 0.4 to 0.9. When the silicon carbide powder according to the embodiment is analyzed by the two-dimensional image analysis, the average particle circularity of the particles contained in the silicon carbide powder according to the embodiment may be 0.4 to 0.8. When the silicon carbide powder according to the embodiment is analyzed by the two-dimensional image analysis, the average particle circularity of the particles contained in the silicon carbide powder according to the embodiment may be 0.45 to 0.75. When the silicon carbide powder according to the embodiment is analyzed by the two-dimensional image analysis, the average particle circularity of the particles contained in the silicon carbide powder according to the embodiment may be 0.5 to 0.7. When the silicon carbide powder according to the embodiment is analyzed by the two-dimensional image analysis, the average particle circularity of the particles contained in the silicon carbide powder according to the embodiment may be 0.55 to 0.7.

[0181] The circularity of the particles can be calculated by the following formula:

[0182] [Formula 1] Particle circularity = 4 x π x particle area / (perimeter) 2

[0183] When the silicon carbide powder according to the embodiment is analyzed by the two-dimensional image analysis, the average particle ovality of the particles contained in the silicon carbide powder according to the embodiment may be 0.85 to 1. When the silicon carbide powder according to the embodiment is analyzed by the two-dimensional image analysis, the average particle ovality of the particles contained in the silicon carbide powder according to the embodiment may be 0.90 to 1. When the silicon carbide powder according to the embodiment is analyzed by the two-dimensional image analysis, the average particle ovality of the particles contained in the silicon carbide powder according to the embodiment may be 0.91 to 1. When the silicon carbide powder according to the embodiment is analyzed by the two-dimensional image analysis, the average particle ovality of the particles contained in the silicon carbide powder according to the embodiment may be 0.93 to 1. In one embodiment, the particle ovality measured by the two-dimensional image analysis may be 0.92 or more.

[0184] When the silicon carbide powder according to the embodiment is analyzed by the two-dimensional image analysis, the particles contained in the silicon carbide powder according to the embodiment may have an average particle tortuosity of about 0.83 to about 0.99.

[0185] The tortuosity of the particle can be calculated according to the following Equation 2:

[0186] [Formula 2] Tortuosity of a particle = convex hull / perimeter

[0187] When the silicon carbide powder according to the embodiment is analyzed by the two-dimensional image analysis, the average particle tortuosity of the particles contained in the silicon carbide powder according to the embodiment may be about 0.83 to about 0.99. When the silicon carbide powder according to the embodiment is analyzed by the two-dimensional image analysis, the average particle tortuosity of the particles contained in the silicon carbide powder according to the embodiment may be about 0.84 to about 0.98. When the silicon carbide powder according to the embodiment is analyzed by the two-dimensional image analysis, the average particle tortuosity of the particles contained in the silicon carbide powder according to the embodiment may be about 0.85 to about 0.95. When the silicon carbide powder according to the embodiment is analyzed by the two-dimensional image analysis, the average particle tortuosity of the particles contained in the silicon carbide powder according to the embodiment may be about 0.86 to about 0.94. In one embodiment, the particle tortuosity measured by the two-dimensional image analysis may be 0.9 to 0.99.

[0188] When the silicon carbide powder according to the embodiment is analyzed by the two-dimensional image analysis, the average particle elongation of the particles contained in the silicon carbide powder according to the embodiment may be about 0.8 to about 0.95.

[0189] The degree of elongation of the particles can be calculated according to the following formula 3.

[0190] [Formula 3] Particle elongation = equivalent circle diameter / maximum length

[0191] The closer the particle's degree of elongation is to 1, the closer the two-dimensional image of the particle is to a bunched shape, and the closer the particle's degree of elongation is to 0, the closer the two-dimensional image of the particle is to an elongated shape.

[0192] When the silicon carbide powder according to the embodiment is analyzed by the two-dimensional image analysis, the average particle elongation of the particles contained in the silicon carbide powder according to the embodiment may be about 0.81 to about 0.95. When the silicon carbide powder according to the embodiment is analyzed by the two-dimensional image analysis, the average particle elongation of the particles contained in the silicon carbide powder according to the embodiment may be about 0.82 to about 0.94. When the silicon carbide powder according to the embodiment is analyzed by the two-dimensional image analysis, the average particle elongation of the particles contained in the silicon carbide powder according to the embodiment may be about 0.83 to about 0.93.

[0193] When the silicon carbide powder according to the embodiment is analyzed by the two-dimensional image analysis, the average charging space elongation of the particles included in the silicon carbide powder according to the embodiment may be 0.65 to 0.85.

[0194] The stretching degree of the charging space can be calculated by the following Equation 4.

[0195] [Formula 4] Charging space expansion rate = equivalent circle diameter / maximum frame diameter

[0196] The closer the degree of elongation of the charging space is to 1, the closer the space occupied by the particles is to a gathered shape. Conversely, the closer the degree of elongation of the charging space is to 0, the closer the space occupied by the particles is to an elongated shape.

[0197] When the silicon carbide powder according to the embodiment is analyzed by the two-dimensional image analysis, the average charging space extension of the particles contained in the silicon carbide powder according to the embodiment may be 0.68 to 0.83. When the silicon carbide powder according to the embodiment is analyzed by the two-dimensional image analysis, the average charging space extension of the particles contained in the silicon carbide powder according to the embodiment may be 0.70 to 0.83. When the silicon carbide powder according to the embodiment is analyzed by the two-dimensional image analysis, the average charging space extension of the particles contained in the silicon carbide powder according to the embodiment may be 0.70 to 0.80. When the silicon carbide powder according to the embodiment is analyzed by the two-dimensional image analysis, the average charging space extension of the particles contained in the silicon carbide powder according to the embodiment may be 0.73 to 0.80.

[0198] When the silicon carbide powder according to the embodiment is analyzed by the two-dimensional image analysis, the tortuosity of the average charging space of the particles included in the silicon carbide powder according to the embodiment may be 0.7 to 0.96.

[0199] The curvature of the charging space can be calculated by the following Equation 5.

[0200] [Formula 5] Curvature of charging space = equivalent circle diameter / intermediate frame diameter

[0201] When the silicon carbide powder according to the embodiment is analyzed by the two-dimensional image analysis, the tortuosity of the average charging space of the particles included in the silicon carbide powder according to the embodiment may be 0.75 to 0.94. When the silicon carbide powder according to the embodiment is analyzed by the two-dimensional image analysis, the tortuosity of the average charging space of the particles included in the silicon carbide powder according to the embodiment may be 0.79 to 0.94. When the silicon carbide powder according to the embodiment is analyzed by the two-dimensional image analysis, the tortuosity of the average charging space of the particles included in the silicon carbide powder according to the embodiment may be 0.83 to 0.94. When the silicon carbide powder according to the embodiment is analyzed by the two-dimensional image analysis, the tortuosity of the average charging space of the particles included in the silicon carbide powder according to the embodiment may be 0.85 to 0.94. When the silicon carbide powder according to the embodiment is analyzed by the two-dimensional image analysis, the tortuosity of the average charging space of the particles included in the silicon carbide powder according to the embodiment may be 0.85 to 0.93.

[0202] Referring to FIG. 7, a silicon carbide wafer according to an embodiment can be manufactured as follows.

[0203] First, a silicon carbide ingot can be produced by applying physical vapor transport (PVT) so that the silicon carbide ingot has a large area and has few defects.

[0204] A method for producing silicon carbide ingot 12 according to one embodiment may include a preparation step, a silicon carbide powder loading step, and a growing step.

[0205] The preparation step is a step of preparing a crucible assembly including a crucible body 20 having an internal space and a crucible lid 21 covering the crucible body.

[0206] The silicon carbide powder charging step is a step of charging silicon carbide powder 30 into the crucible assembly so that a seed crystal is disposed on the raw material at a certain interval from the raw material.

[0207] The crucible body 20 may be, for example, a cylindrical body having an opening on the top surface, and may have a structure in which a silicon carbide raw material can be charged. The crucible body 20 has a density of 1.70 g / cm 3 ~1.90g / cm 3 The material of the crucible body 20 may include graphite.

[0208] The crucible lid 21 has a density of 1.70 g / cm 3 ~1.90g / cm 3 The material of the crucible lid 21 may contain graphite. The crucible lid 21 may have a shape that covers the entire opening of the crucible body 20.

[0209] The crucible lid 21 may cover a part of the opening of the crucible body 20 or may include a through hole (not shown). In this case, the vapor transfer rate can be adjusted in the crystal growth atmosphere described later.

[0210] In addition, a seed crystal holder 22 is disposed on the crucible lid 21. The seed crystal holder 22 may be coupled to the crucible lid 21. The seed crystal holder 22 may be attached to the crucible lid 21. The seed crystal holder 22 may be formed integrally with the crucible lid 21.

[0211] The crucible lid 21 may have a thickness of about 10 mm to about 50 mm, and the seed crystal holder 22 may have a thickness of about 1 mm to about 10 mm.

[0212] A seed crystal is prepared to produce the silicon carbide ingot. The seed crystal may be any of wafers having an off-angle selected from the range of 0 to 8 degrees with respect to the (0001) plane.

[0213] The seed crystal may be a substantially single crystalline 4H SiC ingot with minimal defects or polymorphic inclusions. The silicon carbide seed crystal may consist essentially of 4H SiC.

[0214] The seed crystal may have a spherical diameter of 4 inches or more, 5 inches or more, or even 6 inches or more. More specifically, the seed crystal may have a diameter of 4 to 12 inches, 4 to 10 inches, or 6 to 8 inches.

[0215] The seed crystal is adhered to a seed crystal holder. The seed crystal holder comprises graphite. The seed crystal holder may be made of graphite. The seed crystal holder may comprise anisotropic graphite. More particularly, the seed crystal holder may be made of anisotropic graphite.

[0216] The seed crystal and the seed crystal holder are bonded to each other by an adhesive layer, the adhesive layer including a graphite filler and a carbide such as a phenolic resin, and the adhesive layer may have a low porosity.

[0217] The seed crystal may be oriented with the C-plane facing downward.

[0218] Then, silicon carbide powder according to the present embodiment is charged into the crucible to produce the silicon carbide ingot.

[0219] The silicon carbide powder 30 includes a carbon source and a silicon source. Specifically, the silicon carbide powder 30 includes a carbon-silicon source. The silicon carbide powder 30 may have the characteristics described above.

[0220] The silicon carbide powder 30 may contain particles having a size of 75 μm or less in an amount of 15 wt % or less, 10 wt % or less, or 5 wt % or less based on the total raw material. In this way, when a raw material having a relatively small content of particles having a small size is used, it is possible to manufacture a silicon carbide ingot that can reduce the occurrence of defects in the ingot, is more advantageous in controlling the degree of supersaturation, and can provide a wafer with improved crystal properties.

[0221] The silicon carbide powder 30 may be necked or non-necked to each other. When raw materials having these grain sizes are applied, silicon carbide ingots can be produced that provide wafers with better crystallographic properties.

[0222] In the step of charging the silicon carbide powder, the crucible assembly may have a weight ratio (Rw) of 1.5 to 2.7 (times) when the weight of the silicon carbide powder 30 is taken as 1. Here, the weight of the crucible assembly means the weight of the crucible assembly excluding the raw material, and specifically, it is the value obtained by subtracting the weight of the input raw material from the crucible assembly assembled including the seed crystal, regardless of whether a seed holder is applied to the crucible assembly.

[0223] If the weight ratio is less than 1.5, the degree of supersaturation in the crystal growth atmosphere may increase too much, and the crystal quality of the ingot may deteriorate. If the weight ratio is more than 2.7, the degree of supersaturation may decrease, and the crystal quality of the ingot may deteriorate.

[0224] The weight ratio may be 1.6 to 2.6, or may be 1.7 to 2.4. When the weight ratio is within this range, an ingot having excellent defect characteristics and crystallinity characteristics can be produced.

[0225] The crucible assembly may have a length ratio, which is a ratio of a length from a lowermost surface where the silicon carbide powder 30 is located to a surface of the seed crystal 11, when a diameter of an internal space of the crucible body 20 is taken as 1, that is, more than 1 time and not more than 2.5 times.

[0226] The growing step is a step of adjusting the internal space of the crucible body 20 to a crystal growing atmosphere, vapor-transferring the raw material to the seed crystal and depositing it thereon, thereby providing a silicon carbide ingot grown from the seed crystal.

[0227] The growth step includes a process of adjusting the internal space of the crucible assembly to a crystal growth atmosphere, and specifically, the growth step can be performed by surrounding the crucible assembly with a thermal insulator 40, providing a reaction vessel (not shown) including the crucible assembly and the thermal insulator surrounding it, placing this in a reaction chamber such as a quartz tube, and then heating the crucible using a heating means.

[0228] The reaction vessel is located within the reaction chamber 42, and the inner space of the crucible body 20 is induced to a temperature suitable for the crystal growth atmosphere by a heating means 50. These temperatures are one of the important factors for the crystal growth atmosphere, and a more suitable crystal growth atmosphere is formed by adjusting conditions such as pressure and gas movement. A heat insulating material 40 is located between the reaction chamber 42 and the reaction vessel, which makes it easier to form and control the crystal growth atmosphere.

[0229] The thermal insulation material 40 may affect the temperature gradient inside the crucible body or inside the reaction vessel in a growth atmosphere. Specifically, the thermal insulation material may include a graphite thermal insulation material, and more specifically, the thermal insulation material may include a rayon-based graphite felt or a pitch-based graphite felt.

[0230] In an embodiment, the insulating material may have a density of about 0.12 g / cc to about 0.30 g / cc. In an embodiment, the insulating material may have a density of about 0.13 g / cc to about 0.25 g / cc. In an embodiment, the insulating material may have a density of about 0.14 g / cc to about 0.20 g / cc.

[0231] When the density of the insulating material is less than about 0.14 g / cc, the shape of the grown ingot may grow concave, and 6H-SiC polymorphism may occur, resulting in poor quality of the ingot.

[0232] If the density of the insulation exceeds about 0.30 g / cc, the grown ingot may grow excessively convex, resulting in a low edge growth rate, which may reduce the yield or increase the occurrence of cracks in the ingot.

[0233] The insulating material can improve the quality of the ingot more than when a material having a density of about 0.12 g / cc to about 0.30 g / cc is used, and when a material having a density of about 0.14 g / cc to about 0.20 g / cc is used, it is better to control the crystal growth atmosphere during the ingot growth process and grow an ingot of better quality.

[0234] The insulating material may have a porosity of about 73 vol% to about 95 vol%. The insulating material may have a porosity of about 76 vol% to about 93 vol%. The insulating material may have a porosity of 81 vol% to 91 vol%. When insulating materials having these porosities are used, the frequency of cracks occurring in the ingot can be further reduced.

[0235] The insulating material may have a compressive strength of about 0.21 MPa or more. The insulating material may have a compressive strength of about 0.49 MPa or more. The insulating material may have a compressive strength of about 0.78 MPa or more. The insulating material may have a compressive strength of about 3 MPa or less, or about 25 MPa or less. When the insulating material has these compressive strengths, it is possible to produce a SiC ingot of better quality by having excellent thermal / mechanical stability and a reduced probability of ash generation.

[0236] The insulating material may be applied in a thickness of about 20 mm or more, and may be applied in a thickness of about 30 mm or more. The insulating material may be applied in a thickness of about 150 mm or less, about 120 mm or less, and about 80 mm or less. When the insulating material is applied in these thickness ranges, a sufficient insulating effect can be obtained without unnecessary waste of the insulating material.

[0237] The insulating material 40 may have a density of about 0.12 g / cc to about 0.30 g / cc. The insulating material 40 may have a porosity of about 72 vol% to about 90 vol%. When these insulating materials are used, it is possible to suppress the ingot from growing in a concave or excessively convex shape, and it is possible to reduce the phenomenon of the deterioration of the polymorph quality or the occurrence of cracks in the ingot.

[0238] The crystal growth atmosphere can be generated by heating the reaction chamber 42 using an external heating means (50). The atmosphere can be reduced in pressure to remove air, either simultaneously with or separately from the heating, and the crystal growth atmosphere can be generated in a reduced pressure atmosphere and / or an inert atmosphere (e.g., an Ar atmosphere, a N2 atmosphere, or a mixture thereof).

[0239] The crystal growth atmosphere induces the growth of silicon carbide crystals by vapor transport of source material to the surface of the seed crystal, causing it to grow into an ingot 12 .

[0240] The crystal growth atmosphere can have a growth temperature of 2100° C. to 2450° C. and a growth pressure of 1 torr to 100 torr. When these temperatures and pressures are applied, silicon carbide ingots can be produced more efficiently.

[0241] Specifically, the crystal growth atmosphere may be such that the surface temperature of the upper and lower parts of the crucible is 2100°C to 2450°C and the growth pressure is 1 torr to 50 torr, and more specifically, the surface temperature of the upper and lower parts of the crucible is 2150°C to 2450°C and the growth pressure is 1 torr to 40 torr.

[0242] More specifically, a growth temperature of 2150 to 2350° C. at the upper and lower surfaces of the crucible and a growth pressure of 1 torr to 30 torr can be applied.

[0243] Application of the above-mentioned crystal growth atmosphere is advantageous in producing a higher quality silicon carbide ingot by the production method of the present invention.

[0244] The silicon carbide ingot 12 contains 4H SiC and may have a convex or flat surface.

[0245] If the surface of the silicon carbide ingot 12 is formed concavely, in addition to the intended 4H-SiC crystal, other polymorphs such as 6H-SiC may be mixed in, which may reduce the quality of the silicon carbide ingot. Also, if the surface of the silicon carbide ingot is formed too convexly, cracks may occur in the ingot itself or the crystals may be crushed when processed into wafers.

[0246] At this time, whether or not the silicon carbide ingot 12 is an excessively convex ingot is determined based on the degree of warpage, and the silicon carbide ingot produced in this specification has a warpage of approximately 20 mm or less.

[0247] The warpage is evaluated by placing a sample of silicon carbide ingot on a platen, measuring the height of the center and edge of the ingot with a height gauge based on the rear surface of the ingot, and determining the value of (center height - edge height). A positive value of the warpage indicates a convex shape, a value of 0 indicates a flat shape, and a negative value indicates a concave shape.

[0248] Specifically, the silicon carbide ingot 12 has a convex or flat surface and may have a warpage of about 0 mm to about 14 mm, about 0 mm to about 11 mm, or about 0 mm to about 8 mm. Silicon carbide ingots having these degrees of warpage are easier to process into wafers and can reduce the occurrence of cracks.

[0249] The silicon carbide ingot 12 may be a substantially single crystal 4H SiC ingot with minimal defects or polymorphic inclusions. The silicon carbide ingot 12 may be substantially made of 4H SiC and may have a convex or flat surface.

[0250] The silicon carbide ingot 12 has reduced defects that may occur in silicon carbide ingots, and can provide silicon carbide wafers of higher quality.

[0251] The silicon carbide ingot produced by the method of the present invention has reduced pits on its surface, and specifically, in an ingot having a diameter of 4 inches or more, the pits contained in the surface are reduced to about 10k / cm 2 It may be the following.

[0252] In the present specification, the surface pits of the silicon carbide ingot are measured by observing a total of five locations using an optical microscope: one location in the center of the surface of the ingot excluding facets, and four locations at the 3 o'clock, 6 o'clock, 9 o'clock, and 12 o'clock positions located approximately 10 mm inward toward the center of the edge of the silicon carbide ingot, and measuring the number of surface pits per unit area (1 cm 3 ) and then the average value is evaluated.

[0253] For example, the silicon carbide ingot may be subjected to external grinding to grind the outer edge of the ingot, and then sliced ​​to a certain thickness, followed by edge grinding, surface grinding, polishing, and other processing.

[0254] The slicing step is a step of slicing a silicon carbide ingot to have a certain off-angle to provide sliced ​​crystals. The off-angle is based on the (0001) plane of 4H SiC. Specifically, the off-angle may be an angle selected from 0 to 15 degrees, an angle selected from 0 to 12 degrees, or an angle selected from 0 to 8 degrees.

[0255] The slicing can be performed by any slicing method that is normally applied in the manufacture of wafers, and examples of the slicing include cutting using a diamond wire or a wire to which diamond slurry is applied, cutting using a blade or wheel to which diamond is partially applied, etc., but are not limited to these.

[0256] The thickness of the sliced ​​crystal may be adjusted taking into consideration the thickness of the wafer to be manufactured, and may be sliced ​​to an appropriate thickness taking into consideration the thickness after polishing in the polishing step described below.

[0257] Also, the slicing starts from a position offset by about 3° from a point where an outer circumferential surface of the silicon carbide ingot meets the second direction, and is performed in the second direction. That is, the direction in which the slicing is performed may be a direction offset by about 3° from the second direction. That is, the movement direction of a sawing wire for slicing may be a direction inclined by about 3° from a direction perpendicular to the second direction. That is, the extension direction of the sawing wire may be a direction inclined by about 3° from a direction perpendicular to the second direction, and the silicon carbide ingot may be gradually cut and cut in a direction inclined by about 3° from the second direction.

[0258] Therefore, the phenomenon of stress occurring in the first direction during the slicing process may be minimized, that is, since no pressure is applied in the first direction during the slicing process, the stress in the first direction may be minimized, and the deviation of the peak omega angle in the first direction may be minimized.

[0259] The polishing step is a step of polishing the sliced ​​crystal to a thickness of 300 to 800 μm to form a silicon carbide wafer.

[0260] The polishing step may be performed using a polishing method generally used in wafer manufacturing, e.g., a method in which processes such as lapping and / or grinding are performed, followed by polishing, etc. may be used.

[0261] The silicon carbide wafer according to the embodiment may have a low surface oxygen concentration. In the silicon carbide wafer according to the embodiment, the surface oxygen concentration measured by the X-ray photoelectron spectroscopy may be about 5 atom% to about 14 atom%. In the silicon carbide wafer according to the embodiment, the surface oxygen concentration measured by the X-ray photoelectron spectroscopy may be about 6 atom% to about 13 atom%. In the silicon carbide wafer according to the embodiment, the surface oxygen concentration measured by the X-ray photoelectron spectroscopy may be about 7 atom% to about 12.5 atom%. In the silicon carbide wafer according to the embodiment, the surface oxygen concentration measured by the X-ray photoelectron spectroscopy may be about 8 atom% to about 12 atom%.

[0262] As a result, the silicon carbide wafer according to the embodiment has a low surface oxygen content, and therefore can realize a high yield when used in a manufacturing process of a power semiconductor device. The silicon carbide wafer according to the embodiment can have a yield of about 88% or more for the manufactured power semiconductor device. That is, a manufacturing method of a power semiconductor device using the silicon carbide wafer according to the embodiment can have a yield of about 88% or more.

[0263] The silicon carbide powder according to the embodiment has a suitable range of particle circularity. The silicon carbide powder according to the embodiment can have a suitable range of particle ellipticity. The silicon carbide powder according to the embodiment can have a suitable range of particle curvature. The silicon carbide powder according to the embodiment can have a suitable range of particle elongation. The silicon carbide powder according to the embodiment can have a suitable range of charging space elongation. The silicon carbide powder according to the embodiment can have a suitable range of charging space curvature.

[0264] Accordingly, the silicon carbide powder according to the embodiment may have an appropriate shape so as to realize appropriate porosity and appropriate thermal conductivity when filled into a crucible to produce silicon carbide ingots and silicon carbide wafers.

[0265] As a result, the silicon carbide powder according to the embodiment has improved thermal conductivity in the horizontal direction when filled in the crucible, and has a suitable range of porosity, and therefore has a uniform temperature gradient in the horizontal direction when filled in the crucible and heated for growing the silicon carbide ingot, and silicon carbide gas sublimated in the pores can be easily transferred to the silicon carbide seed crystal.

[0266] As a result, the silicon carbide powder according to the embodiment can transport the sublimated silicon carbide gas upward at an improved and uniform rate. Therefore, the silicon carbide powder according to the embodiment can improve the growth rate of the silicon carbide ingot. In addition, since the silicon carbide gas is sublimated at a uniform rate overall, defects in the silicon carbide ingot and the silicon carbide wafer can be reduced.

[0267] The growth process of the silicon carbide ingot may depend on the particle shape of the silicon carbide powder according to the embodiment. In this case, the particle shape and surface characteristics of the silicon carbide powder can be appropriately adjusted by the crushing process, the grinding process, and the etching process. The particle shape and surface characteristics of the silicon carbide powder according to the embodiment can be determined by the two-dimensional image analysis. When the silicon carbide powder according to the embodiment has a particle circularity, a particle ellipticity, a particle curvature, a particle elongation, a charging space elongation, and a charging space curvature within an appropriate range, the silicon carbide powder has a particle shape and a particle surface that have a positive effect on the growth of the silicon carbide ingot.

[0268] The present invention will be described in detail with reference to the following specific examples. The following examples are merely illustrative for understanding the embodiments, and are not intended to limit the scope of the invention disclosed in the present specification.

[0269] Manufacturing Example 1 A mass of single crystal silicon carbide is provided as the silicon carbide feedstock. The mass of single crystal silicon carbide may be formed by subliming silicon carbide powder having a purity of about 99.9999% or greater at a temperature of about 2300° C. and depositing the sublimated silicon carbide powder on a seed crystal.

[0270] The single crystal silicon carbide chunks were subjected to primary crushing using a jaw crusher (Henan Dewo Industrial Limited Company, KER-100×60). A primary powder having an average particle size (D50) of about 6 mm was obtained from the crushed silicon carbide chunks.

[0271] The primary powder was then subjected to secondary pulverization using a ball mill (Ganzhou Li Ang Machinery Co., Ltd., QM400*600). At this time, a steel ball having a diameter of about 25.4 mm was placed in a cylinder, and the diameter of the cylinder was about 400 mm. The rotation speed of the cylinder was about 20 rpm, and the secondary pulverization process was carried out for about 15 minutes. The secondary pulverized primary powder was classified using a classifier, and a secondary powder having an average particle size (D50) of about 500 μm was obtained.

[0272] The secondary powder was then heat-treated in an air atmosphere at a temperature of about 1200° C. for about 24 hours to remove carbon-free and silicon-free.

[0273] The heat-treated silicon carbide powder was then purified by a wet etching process.

[0274] The etching solution was prepared by mixing deionized water, hydrofluoric acid, and nitric acid in a volume ratio of approximately 2:1:1.

[0275] Then, about 1 L of the heat-treated silicon carbide powder was added to an etching vessel having a volume of about 5 L, and about 0.8 L of the etching solution was added.

[0276] The etching container was then sealed with a lid. At this time, oil vapor generated in the etching container was discharged through the lid and collected by a scrubber.

[0277] The etchant and the heat treated silicon carbide powder were stirred at about 26 rpm for about 1 hour.

[0278] The etching solution was then drained, and the wet-etched silicon carbide powder was neutralized with deionized water by the following process: the wet-etched silicon carbide powder was immersed in deionized water, stirred, and the deionized water was drained. This immersion and draining process was repeated until the pH of the drained deionized water was 7.

[0279] The neutralized silicon carbide powder was then dried at a temperature of about 80° C. for about 30 minutes.

[0280] The dried silicon carbide powder is then placed into a graphite crucible.

[0281] The temperature inside the crucible is then increased to about 2000° C., and the pressure inside the crucible is reduced to about 8 torr.

[0282] Then, an etching gas, which is a mixture of argon and chlorine gases in a volume ratio of about 10:1, is introduced into the crucible, and the pressure inside the crucible is increased to about 760 torr. At this time, the temperature of the crucible is set so that the temperature of the bottom of the crucible is about 50° C. higher than the temperature of the top of the crucible. This state is maintained for about 2 days.

[0283] Thereafter, the etching gas inside the crucible is collected by a scrubber, and the inside of the crucible in which the dry-etched silicon carbide powder is placed is heat-treated at a temperature of about 1000° C. in an air atmosphere for about 10 hours.

[0284] Thereafter, the heat-treated silicon carbide powder was immersed in an aqueous solution of hydrofluoric acid having a concentration of about 0.5 wt %, and the silicon carbide powder and the aqueous solution of hydrofluoric acid were stirred for about 1 hour.

[0285] The silicon carbide powder treated with the hydrofluoric acid solution was then washed by repeatedly immersing it in ultrapure water and draining the ultrapure water until the concentration of hydrofluoric acid in the drained ultrapure water was reduced to about 0.0001 wt% or less.

[0286] Manufacturing Examples 2 to 6 The primary crushing process and the secondary pulverization process were carried out substantially in the same manner as in Preparation Example 1, as shown in Table 1 below.

[0287] [Table 1]

[0288] As shown in Tables 2 to 4 below, two-dimensional image analysis was performed on the silicon carbide powders in Preparation Examples 1 to 6.

[0289] [Table 2]

[0290] [Table 3]

[0291] [Table 4]

[0292] Working Example Thereafter, the silicon carbide powder produced in Production Example 1 was placed inside the graphite crucible body. A silicon carbide seed crystal and a seed crystal holder were placed on top of the powder. At this time, the silicon carbide seed crystal (4H SiC single crystal, 6 inches) was fixed in a conventional manner so that the C-face (0001) of the silicon carbide seed crystal was facing the bottom of the crucible. In addition, the crucible lid and the seed crystal holder were integrally manufactured and formed from graphite, and both the crucible lid and the seed crystal holder had a disk shape. At this time, the thickness of the crucible lid was about 20 mm, the diameter of the crucible lid was about 210 mm, the thickness of the seed crystal holder was about 3 mm, and the diameter of the seed crystal holder was about 180 mm.

[0293] The crucible body was covered with a crucible lid on which the seed crystal and the seed crystal holder were placed, and was surrounded by a heat insulating material, and then placed in a reaction chamber equipped with a heating coil as a heating means.

[0294] In this case, graphite felt having a density of about 0.19 g / cc, a porosity of about 85 vol%, and a compressive strength of about 0.37 MPa is used as the heat insulating material.

[0295] After creating a vacuum inside the crucible, argon gas was gradually introduced until the inside of the crucible reached atmospheric pressure, and the pressure inside the crucible was gradually reduced. At the same time, the temperature inside the crucible was gradually increased to 2000° C. at a rate of about 3° C. / min, and then to 2350° C. at a rate of about 5° C. / min.

[0296] Then, a SiC ingot was grown from the silicon carbide seed crystal at a temperature of 2350° C. and a pressure of 20 torr for 100 hours.

[0297] The silicon carbide ingot was then cut using a diamond wire saw and processed through a chamfering process, a grinding process, and a polishing process, thereby producing silicon carbide wafers with an off-angle of 4 degrees with respect to the (0001) plane.

[0298] Examples 2 to 7 and Comparative Example The other steps were the same as in Example 1, except that the silicon carbide powder was changed as shown in Table 5 below.

[0299] [Table 5]

[0300] [Table 6]

[0301] Measurement example 1. Purity of silicon carbide powder The purity of the silicon carbide powders from the production examples was measured by glow discharge mass spectrometry.

[0302] 2. Shape of silicon carbide powder The silicon carbide powder produced in the measurement example was sampled about 30 times with a weight of about 1 g. The samples were photographed by an optical microscope (Nikon Eclipse LV150 Microscope) and analyzed by an image analysis program (IMT i-solution). The area, circumference, equivalent circle diameter, maximum ellipse diameter, minimum ellipse diameter, maximum length, maximum frame diameter, minimum frame diameter, mean frame diameter, and convex hull of each particle were measured. Each measurement value from each particle was averaged.

[0303] As shown in Table 6, the silicon carbide powder produced according to the embodiment has a suitable range of particle circularity, particle ellipticity, particle tortuosity, particle elongation, charging space elongation, and charging space tortuosity, so that a silicon carbide ingot having a high growth rate and few defects can be produced. [Explanation of symbols]

[0304] 20 Crucible body 40 Insulation 12 Silicon carbide ingot

Claims

1. Contains carbon and silicon, the circularity of the particles, as measured by two-dimensional image analysis, is between 0.4 and 0.9; The particle tortuosity measured by the two-dimensional image analysis is 0.8 to 0.99; The degree of elongation of the particles measured by the two-dimensional image analysis is 0.7 to 0.95; The equivalent circular diameter measured by the two-dimensional image analysis is 150 μm to 3 mm; The ovality of the particles measured by the two-dimensional image analysis is 0.92 or more. Silicon carbide powder.

2. The degree of elongation of the charging space measured by the two-dimensional image analysis is 0.6 to 0.9; 2. The silicon carbide powder of claim 1.

3. The curvature of the charging space measured by the two-dimensional image analysis is 0.8 to 0.95; 2. The silicon carbide powder of claim 1.

4. The equivalent circular diameter measured by the two-dimensional image analysis is 200 μm to 350 μm; 2. The silicon carbide powder of claim 1.

5. The equivalent circular diameter measured by the two-dimensional image analysis is 350 μm to 700 μm; 2. The silicon carbide powder of claim 1.

6. The equivalent circular diameter measured by the two-dimensional image analysis is 800 μm to 3500 μm; 2. The silicon carbide powder of claim 1.

7. preparing a silicon carbide powder comprising carbon and silicon, the silicon carbide powder having a particle circularity of 0.4 to 0.9 as measured by two-dimensional image analysis, a particle tortuosity of 0.8 to 0.99 as measured by the two-dimensional image analysis, a particle elongation of 0.7 to 0.95 as measured by the two-dimensional image analysis, and an equivalent circular diameter of 150 μm to 3 mm as measured by the two-dimensional image analysis; growing a silicon carbide ingot using the silicon carbide powder; and processing the silicon carbide ingot; In the silicon carbide powder, the ellipticity of the particles measured by the two-dimensional image analysis is 0.92 or more; A method for manufacturing silicon carbide wafers.

8. In the step of growing the silicon carbide ingot, a crucible is filled with the silicon carbide powder; The porosity of the silicon carbide powder filled in the crucible is 10 vol% to 50 vol%, In the step of growing the silicon carbide ingot, the growth rate of the silicon carbide ingot is 250 μm / hr to 400 μm / hr; The method for producing a silicon carbide wafer according to claim 7.

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