JP2018104216A - Silicon carbide powder, and production method of silicon carbide single crystal using the same as raw material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide silicon carbide powder capable of suppressing a defect generated in an obtained silicon carbide single crystal, in the case of being used as a raw material, when producing the silicon carbide single crystal by a sublimation recrystallization method.SOLUTION: In silicon carbide powder, an initial bulk density is 0.85 g/cmor higher and 1.75 g/cmor lower, a tap bulk density is 0.9 g/cmor higher and 1.8 g/cmor lower, and a Blaine specific surface area is 300 cm/g or larger 400 cm/g or smaller. The ratio of the silicon carbide powder whose size range is over 44 μm and 2,000 μm or less is 98.5% or more, and the ratio of the silicon carbide powder whose size range is 44 μm or less is 1.5% or less.SELECTED DRAWING: None

Description

  The present invention relates to a silicon carbide powder and a method for producing a silicon carbide single crystal using the same as a raw material.

  Silicon carbide single crystals are used as materials for molding wheels, ceramic parts and the like because of their high hardness, high thermal conductivity, and high temperature heat resistance. In addition, silicon carbide is attracting attention as a power semiconductor substrate material that replaces silicon because it has properties of about 3 times the band gap and about 10 times the dielectric breakdown electric field strength compared to silicon.

  As a method for producing a silicon carbide single crystal, a sublimation recrystallization method (an improved Rayleigh method) in which a silicon carbide powder as a raw material is sublimated under a high temperature condition of 2000 ° C. or more and a silicon carbide single crystal is grown is well known. Widely used industrially. However, there has been a problem that defects such as stacking faults and dislocation defects are likely to occur in silicon carbide grown by single crystal.

  In order to suppress such defects, it is preferable to reduce impurities in the silicon carbide powder as a raw material. Therefore, it has been proposed to reduce the impurity content from 0.1 ppm to 0.5 ppm or less by producing silicon carbide by a high-frequency plasma CVD method (see, for example, Patent Documents 1 to 3).

However, the high-frequency plasma CVD method can produce high-purity silicon carbide, but it is difficult to use from an industrial point of view because the amount of production at one time is small and the cost is high. Further, silicon carbide powder produced by high frequency plasma CVD method, typically the initial bulk density 1.66 g / cm ^3, the tapped bulk density of 1.85 g / cm ^3, the filling rate when filled into a crucible Is high and the growth rate of the single crystal is slow.

  For this reason, the Atchison method is used as a method for producing silicon carbide that can be produced in large quantities and at low cost. When the silicon carbide powder produced by the Atchison method is used as a raw material for producing a silicon carbide single crystal by the sublimation recrystallization method, the Blaine specific surface area, the bulk density, etc. may be adjusted (for example, Patent Document 4, 5).

JP-A-9-48605 JP 2009-173501 A JP 2002-293525 A JP2015-44726A JP, 2006-147790, A

  However, when silicon carbide powder with a high content of impurities such as boron, phosphorus, aluminum, iron, and titanium is used as the raw material for the sublimation recrystallization method, defects occur in the silicon carbide grown by single crystal, and the power semiconductor substrate In many cases, it became unsuitable as a material.

  The present invention, when used as a raw material for producing a silicon carbide single crystal by a sublimation recrystallization method, provides a silicon carbide powder capable of suppressing defects generated in the resulting silicon carbide single crystal, and a silicon carbide single crystal using this as a raw material. It aims at providing the manufacturing method of a crystal | crystallization.

The silicon carbide powder of the present invention has an initial bulk density of 0.85 g / cm ^{3 to} 1.75 g / cm ³ , a tap bulk density of 0.9 g / cm ^{3 to} 1.8 g / cm ³ , and a brain specific surface area. The silicon carbide powder having a particle size range of not less than 44 μm and not more than 2000 μm, wherein the ratio of the silicon carbide powder is not less than 300 cm ² / g and not more than 400 cm ² / g, and the particle size range is not less than 98.5% and not more than 44 μm. The ratio of the silicon carbide powder is 1.5% or less.

  The silicon carbide powder of the present invention is suitable as a raw material for producing a silicon carbide single crystal by a sublimation recrystallization method. This is because, as described in the detailed description of the invention, when a silicon carbide single crystal is produced by the sublimation recrystallization method, the amount of silicon carbide gas generated in the crucible becomes appropriate, so that the growth of the single crystal In addition to ensuring the speed, the winding of fine impurities and silicon carbide powder due to the release of silicon carbide gas is suppressed, and defects that occur in the silicon carbide single crystal can be suppressed to such an extent that it is suitable as a power semiconductor substrate material. is there.

  In the silicon carbide powder of the present invention, each content of boron, phosphorus, aluminum, iron and titanium is preferably 1.0 ppm or less.

  In this case, winding of boron, phosphorus, aluminum, iron and titanium due to the release of the silicon carbide gas is suppressed, and defects generated in the silicon carbide single crystal can be further suppressed.

Further, in the silicon carbide powder of the present invention, it is preferred that a difference between the initial bulk density and tapped bulk density of 0.05 g / cm ³ or more 0.1 g / cm ³ or less.

  In this case, the filling rate of the silicon carbide powder in the crucible becomes appropriate, and the growth rate of the single crystal can be ensured.

  The method for producing a silicon carbide single crystal of the present invention is characterized in that a silicon carbide single crystal is produced by filling a container with the silicon carbide powder of the present invention as a raw material and sublimating the silicon carbide powder.

  Hereinafter, the silicon carbide powder which concerns on embodiment of this invention is demonstrated.

  This silicon carbide powder is suitable as a raw material for producing a silicon carbide single crystal by a sublimation recrystallization method.

The silicon carbide powder has an initial bulk density of 0.85 g / cm ³ or more and 1.75 g / cm ³ or less, preferably 1.0 g / cm ³ or more and 1.7 g / cm ³ or less, more preferably 1.2 g. / Cm ³ or more and 1.60 g / cm ³ or less.

If the initial bulk density is less than 0.85 g / cm ³ , the silicon carbide powder particles are too large, and the filling rate in the crucible when manufactured by the sublimation recrystallization method becomes too small. The amount is reduced and the growth rate of the single crystal is reduced. On the other hand, when the initial bulk density exceeds 1.75 g / cm ³ , the proportion of fine silicon carbide powder becomes too high, and the silicon carbide gas hardly flows in the crucible, so that the growth rate of the single crystal becomes slow.

The silicon carbide powder has a tap bulk density of 0.9 g / cm ³ or more and 1.8 g / cm ³ or less, preferably 1.0 g / cm ³ or more and 1.75 g / cm ³ or less, more preferably 1.2 g. / Cm ³ or more and 1.7 g / cm ³ or less.

If the tap bulk density is less than 0.9 g / cm ³ , the filling rate in the crucible becomes too small, many escape paths for silicon carbide gas are formed, a large amount of gas is released, and fine impurities or silicon carbide powder Rolls up. On the other hand, if the tap bulk density exceeds 1.8 g / cm ³ , the amount of fine silicon carbide powder increases so much that the voids through which the silicon carbide gas flows in the crucible decrease, making it difficult for the gas to flow and the internal pressure to be reduced. As a result of the increase, gas is rapidly ejected, and fine impurities or silicon carbide powder is rolled up. These wound powders and the like are present in the obtained silicon carbide single crystal, and become a starting point for defects.

This silicon carbide powder, it is preferred that a difference between the tapped bulk density and the initial bulk density of 0.05 g / cm ³ or more 0.1 g / cm ³ or less, more preferably 0.06 g / cm ³ or more 0.09g / Cm ³ or less, still more preferably 0.07 g / cm ³ or more and 0.09 g / cm ³ or less.

The silicon carbide powder produced by the high-frequency plasma CVD method has a difference between the tap bulk density and the initial bulk density of about 0.2 g / cm ³ , and this large difference means that the silicon carbide powder particles are spherical. This shows that the shape is distant and distorted, and the filling rate in the crucible becomes too small, so that the growth rate of the single crystal becomes slow.

  The initial bulk density and the tap bulk density may be measured according to the measuring method described in JIS R 1628: 1999 “Method for measuring bulk density of fine ceramic powder”.

This silicon carbide powder, the Blaine specific surface area of not more than 300 cm ² / g or more 400 cm ² / g, preferably from 320 cm ² / g or more 380 cm ² / g or less, more preferably 340 cm ² / g or more 360 cm ² / g or less is there.

If the Blaine specific surface area is less than 300 cm ² / g, the surface area of the silicon carbide powder is too small, so the amount of silicon carbide gas generated is small and the growth rate of the single crystal is slow. On the other hand, if the Blaine specific surface area exceeds 400 cm ² / g, the surface area of the silicon carbide powder is too large, so that a silicon carbide gas is rapidly generated and a large amount of gas is released all at once. Roll up.

  The silicon carbide powder has a particle size range of 44 μm to 2000 μm and a proportion of 98.5% or more and 44 μm or less of a particle size range of 1.5% or less, preferably more than 44 μm and 2000 μm or less. The ratio of those having a particle size range of 99% or more and 44 μm or less is 1.0% or less, more preferably the ratio of those having a particle size range of more than 44 μm and 2000 μm or less is 99.5%. Hereinafter, the ratio of the particle size range of 44 μm or less is 0.5% or less.

  When the proportion of the fine silicon carbide powder having a particle size range of 44 μm or less exceeds 1.5%, the silicon carbide powder wound up by the silicon carbide gas generated in the crucible increases too much, and the resulting silicon carbide single crystal is carbonized. Defects starting from silicon powder occur, making it unsuitable as a power semiconductor substrate material.

  Note that the powder particle size range exceeding A and less than B means that D5 of the particle size distribution of the powder exceeds A and D95 is less than B. That is, it means that the weight under the sieve when sieved with the sieve of A is less than 5%, and the weight of the sieve when sieved with the sieve B is 5% or less.

  Furthermore, the silicon carbide powder preferably has a silicon carbide purity of 99.7% or more, more preferably 99.8% or more, and further preferably 99.9% or more.

  The silicon carbide powder has a content of each of boron (B), phosphorus (P), aluminum (Al), iron (Fe), and titanium (Ti), which are impurities, of 1.0 ppm or less. Preferably, it is 0.8 ppm or less, more preferably 0.75 ppm or less. In particular, the iron content is preferably 0.8 ppm or less.

  In addition, the silicon carbide powder may have a content of at least one or all of boron, phosphorus, aluminum, iron, and titanium, which are impurities, exceeding 0.5 ppm.

  When the purity of silicon carbide is low and the content of impurities such as boron, phosphorus, aluminum, iron and titanium is high, the amount of impurity powder wound up in the silicon carbide gas generated in the crucible increases, and the resulting silicon carbide single crystal Defects starting from the powder of impurities are generated inside, making it unsuitable as a power semiconductor substrate material. However, the lower the impurity content, the better.

  The present invention has a somewhat high content of impurities contained in silicon carbide powder, for example, for power semiconductors even if the content of at least one of boron, phosphorus, aluminum, iron and titanium is 0.5 ppm or more. It is significant to obtain a silicon carbide single crystal that is suitable for the base material and has reduced defects.

  Next, the manufacturing method of the silicon carbide powder which concerns on embodiment of this invention is demonstrated. This manufacturing method is an Atchison method in which a raw material is fired using an Atchison furnace.

  The method for producing the silicon carbide powder includes a step of mixing an inorganic siliceous raw material containing silicon and a carbonaceous raw material containing carbon to obtain a mixed raw material, and firing the mixed raw material at 2500 ° C. or higher to form silicon carbide. A step of obtaining a lump, a step of introducing an inert gas and air-cooling the lump to room temperature, a step of crushing the air-cooled lump, and classifying the obtained pulverized product to obtain silicon carbide powder Process.

  Examples of the inorganic siliceous raw material include crystalline silica such as silica, amorphous silica such as silica fume and silica gel. These may be used alone or in combination of two or more. The average particle size of the inorganic siliceous raw material is appropriately selected depending on the environment during firing, the state of the raw material (crystalline or non-crystalline), the reactivity with the carbonaceous raw material, and the like. However, it is preferable to use amorphous silica as the inorganic siliconaceous raw material because the reactivity during firing is good and the furnace is easily controlled.

  Examples of the carbonaceous raw material include crystalline carbon such as natural graphite and artificial graphite, and amorphous carbon such as carbon black, coke and activated carbon. These may be used alone or in combination of two or more. The average particle size of the carbonaceous raw material is appropriately selected depending on the environment during firing, the state of the raw material (crystalline or amorphous), the reactivity with the carbonaceous raw material, and the like.

  An inorganic siliceous raw material and a carbonaceous raw material are mixed to prepare a mixed raw material. The mixing method at this time is arbitrary, and may be either wet mixing or dry mixing. The mixing molar ratio (C / Si) of the carbonaceous raw material and inorganic siliceous raw material during mixing is selected in consideration of the environment during firing, the particle size of the silicon carbide powder raw material, reactivity, etc. To do. The term “optimum” as used herein means improving the yield of silicon carbide obtained by firing and reducing the unreacted residual amount of the inorganic siliceous raw material and carbonaceous raw material.

  The obtained mixed raw material and raw material for the heating element are filled in an Atchison furnace and fired at 2500 ° C. or higher to obtain massive silicon carbide. A general furnace may be used as the Atchison furnace. The firing atmosphere is preferably a reducing atmosphere. This is because the yield of silicon carbide is reduced when fired in an atmosphere having low reducing ability.

  In the present specification, the “Atchison furnace” refers to a box-type indirect resistance heating furnace having an open top. Here, the indirect resistance heating does not directly flow an electric current to an object to be heated, but obtains silicon carbide by a heating element that generates heat by flowing an electric current. An example of a specific configuration of such an Atchison furnace is described in Japanese Patent Laid-Open No. 2013-112544.

By using such a furnace, the reaction shown in Formula (1) occurs, and a lump made of silicon carbide (SiC) is obtained.
SiO ₂ + 3C → SiC + 2CO (1)

  The type of the heating element of the Atchison furnace is not particularly limited as long as it can conduct electricity, and examples thereof include graphite powder and carbon rod.

  The form of the substance constituting the heating element is not particularly limited, and examples thereof include powder and lump. The heating element is provided so as to have a rod-like shape as a whole so as to connect the electrode cores provided at both ends in the energizing direction of the Atchison furnace. Examples of the rod shape here include a columnar shape and a prismatic shape.

  After energization, a lump made of silicon carbide is generated in the furnace.

  Air cooling is performed by introducing an inert gas such as argon gas until the temperature inside the furnace reaches room temperature. And the lump (ingot) which consists of obtained silicon carbide is grind | pulverized. The pulverization method is not particularly limited, and examples thereof include a pulverization method using a jaw crusher, a top grinder, a jet mill, a ball mill, a disk mill and the like as a pulverizer.

  Thereafter, the pulverized product is classified using a sieve corresponding to the particle size range. For classification, a method using a sieve is the simplest and preferable. However, classification is not limited to a method using a sieve, and may be either dry or wet. Further, as a dry classification, for example, a centrifugal classification method using an air flow can be used.

  The present silicon carbide powder that satisfies the above-mentioned conditions by mixing a plurality of groups such as a group of silicon carbide powders classified into a predetermined particle size range or a group of powders pulverized by different pulverization methods in an appropriate ratio. Can be obtained.

  Next, the manufacturing method of the silicon carbide single crystal using the silicon carbide powder which concerns on embodiment of this invention is demonstrated. This production method is a method for producing a silicon carbide single crystal by the sublimation recrystallization method using the above-described silicon carbide powder as a raw material.

  First, the raw material silicon carbide powder is filled into a crucible made of graphite, for example, and this crucible is disposed in a heating device. However, the container in which the silicon carbide powder is filled is not limited to a graphite crucible, and any container may be used as long as it is used when producing a silicon carbide single crystal by a sublimation recrystallization method.

  And it heats so that the raw material in a crucible may become 2000-2500 degreeC under pressure reduction which made the crucible inert gas atmosphere, such as argon gas. However, the temperature of the portion where the silicon carbide single crystal grows on the lower surface of the lid of the crucible is about 100 ° C. lower than this. A seed crystal may be provided on the lower surface of the lid.

  This heating is continued for several hours to several tens of hours. Thereby, the silicon carbide powder as a raw material is sublimated to become a sublimation gas, reaches the lower surface of the lid and is single-crystallized, and this single crystal grows, whereby a lump of silicon carbide single crystal can be obtained.

  The shape of the silicon carbide particles obtained by pulverizing the lump obtained by firing in an Atchison furnace or the like differs depending on the pulverization method or particle size, and the initial bulk density, tap bulk density, Blaine specific surface area, and the like also differ.

  Thus, silicon carbide powders having different initial bulk densities, tap bulk densities, and brain specific surface areas can be obtained by changing the pulverization method, particle size range, and the like. Then, the silicon carbide powder obtained by changing the pulverization method, the particle size range, etc. may be mixed at an appropriate ratio so that the initial bulk density, tap bulk density, brane specific surface area, particle size range, etc. satisfy the above-mentioned ranges. .

  Examples of the present invention will be described below. However, the present invention is not limited to these examples.

  In each of the examples and comparative examples, the boron content in the impurities is calculated by Shigeru Terashima, Takashi Okai and Masami Taniguchi, “Technical Letter Geological Standards by Alkali Melting / Inductively Coupled Plasma Atomic Emission Spectroscopy”, Japan Analytical Chemistry. Society, BUNSEKI KAGAKU Vol. 47 (1998). 7, p. It measured by the ICP-AES analysis by the alkali melting method described in 451-454.

  The content of phosphorus, aluminum, iron and titanium among the impurities is measured by ICP-AES analysis by the pressurized acid analysis method specified in “JIS R 1616 (2007) Chemical analysis method of fine powder of silicon carbide for fine ceramics”. did.

Example 1
First, amorphous silica powder manufactured by Taiheiyo Cement Co., Ltd. was prepared as an inorganic siliceous material. This silica powder has a particle size of 2 mm, and as a result of measuring impurities, boron is 0.5 ppm, phosphorus is less than 1.0 ppm, aluminum is 0.5 ppm, iron is 0.5 ppm, titanium is 0.6 ppm, respectively. Contained. Carbon black (amorphous carbon, trade name: Seest V) manufactured by Tokai Carbon Co., Ltd. was prepared as a carbonaceous raw material.

These raw materials were mixed so that the molar ratio of carbon to silicon (C: SiO ₂ ) was 3.1: 1 to obtain a mixed raw material.

  The mixed raw material and the raw material for the heating element were filled in an Atchison furnace. As a raw material for a heating element, graphite powder made by Taiheiyo Cement was used. The graphite powder placed in the center of the Atchison furnace was energized for 24 hours while applying a load of 120 kW through the electrode. Thereby, a cylindrical lump of silicon carbide was obtained.

  The obtained cylindrical lump was first pulverized to 2 mm or less using a jaw crusher, top grinder and jet mill. Next, this pulverized product was separated into a powder A of 1 mm or more and less than 2 mm, a powder B of 150 μm or more and 1 mm or less, and a powder C of 44 μm or less using an automatic sieving machine.

Then, the weight ratio of powder A was adjusted to 40%, powder B was adjusted to 54.7%, and powder C was adjusted to a ratio of 0.3% to obtain silicon carbide powder. The initial bulk density of this silicon carbide powder is 1.60 g / cm ³ , the tap bulk density is 1.66 g / cm ³ , the brane specific surface area is 390 cm ² / g, and the proportion of powder with a particle size of 44 μm or less is 0.3%. there were. The initial bulk density, tap bulk density, and Blaine specific surface area were measured by the measurement method described above. These measurement results are summarized in Table 1.

  The silicon carbide powder was acid washed with 17% hydrochloric acid and then dried at a drying temperature of 150 ° C. for 2 days. The impurity content of this silicon carbide powder was measured. Table 2 summarizes the content measurement results.

  Next, the dried silicon carbide powder was filled into a graphite crucible. A single crystal plate with a silicon (Si) surface exposed by polishing as a seed crystal was placed at the center of the crucible lid, and the crucible was covered with this lid.

  The crucible was placed in a heating device and heated under a pressure of 1 Torr (133 Pa). In this heating, the temperature measured by a radiation thermometer that measures the center of the bottom of the crucible was first increased at a rate of temperature increase of 10 ° C./min. After reaching 2200 ° C., the state was maintained for 10 hours. .

  Thereafter, the inside of the crucible was cooled to room temperature. A lump of silicon carbide single crystal having a thickness of 20 mm was formed on the seed crystal. The defect occurrence state of this silicon carbide single crystal was inspected using a SiC wafer defect inspection apparatus manufactured by Lasertec Corporation. The evaluation results are shown in Table 1.

  As can be seen from the evaluation results, it was confirmed that the obtained silicon carbide single crystal was free of stacking faults and dislocation defects to the extent that it was at least unsuitable as a power semiconductor substrate material.

(Example 2)
In Example 2, the silicon carbide powder obtained by pulverizing the lump in Example 1 was pulverized to 2 mm or less using a jaw crusher, a top grinder, and a ball mill. Next, this pulverized product was separated into a powder A of 0.9 mm or more and less than 1.5 mm, a powder B of 150 μm or more and 0.5 mm or less, and a powder C of 44 μm or less using an automatic sieving machine.

Then, the weight ratio of powder A was adjusted to 30%, powder B was adjusted to 69.9%, and powder C was adjusted to a ratio of 0.1% to obtain silicon carbide powder. This initial bulk density of the silicon carbide powder is 1.35 g / cm ^3, a tap bulk density 1.43 g / cm ^3, Blaine specific surface area of 370 cm ² / g, the following proportions of the powder particle size 44μm is 0.1% there were.

  The silicon carbide powder was subjected to acid cleaning and drying in the same manner as in Example 1, and then the impurity content was measured.

  Next, using this silicon carbide powder as a raw material, a lump of silicon carbide single crystal having a thickness of 20 mm was obtained in the same manner as in Example 1. In the obtained silicon carbide single crystal, it was confirmed that stacking faults and dislocation defects were not generated at least so as to be unsuitable as a power semiconductor substrate material.

(Example 3)
In Example 3, the silicon carbide powder obtained by pulverizing the lump in Example 1 was pulverized to 2 mm or less using a jaw crusher, top grinder, and ball mill in the same manner as in Example 2. However, the operation time of the ball mill was shortened by 30 minutes compared with Example 2. Next, this pulverized product was separated into a powder A of 1.0 mm to less than 2.0 mm and a powder B of 350 μm to 1.0 mm using an automatic sieving machine.

And by adjusting the weight ratio of powder A to 50% and powder B to 50%, silicon carbide powder was obtained. This initial bulk density of the silicon carbide powder is 1.05 g / cm ^3, a tap bulk density 1.14 g / cm ^3, Blaine specific surface area of 350 cm ² / g, particle size ratio of the following powder 44μm was 0% .

  The silicon carbide powder was subjected to acid cleaning and drying in the same manner as in Example 1, and then the impurity content was measured.

  Next, using this silicon carbide powder as a raw material, a lump of silicon carbide single crystal having a thickness of 20 mm was obtained in the same manner as in Example 1. In the obtained silicon carbide single crystal, it was confirmed that stacking faults and dislocation defects were not generated at least so as to be unsuitable as a power semiconductor substrate material.

(Comparative Example 1)
In Comparative Example 1, the silicon carbide powder obtained by pulverizing the lump in Example 1 was pulverized to 2 mm or less in the same manner as in Example 1. As such, the as-ground silicon carbide powder has an initial bulk density of 1.20 g / cm ³ , a tap bulk density of 1.23 g / cm ³ , a Blaine specific surface area of 360 cm ² / g, and a particle size of 44 μm or less. The percentage was 1.7%.

  The silicon carbide powder was subjected to acid cleaning and drying in the same manner as in Example 1, and then the impurity content was measured.

  Next, using this silicon carbide powder as a raw material, a lump of silicon carbide single crystal having a thickness of 20 mm was obtained in the same manner as in Example 1. In the obtained silicon carbide single crystal, at least dislocation defects that were inappropriate as a power semiconductor substrate material were not generated, but it was confirmed that stacking faults were generated.

(Comparative Example 2)
In Comparative Example 2, the silicon carbide powder obtained by pulverizing the lump in Example 1 was pulverized to 2 mm or less using a jaw crusher, top grinder, and ball mill in the same manner as in Example 2. However, the operation time of the ball mill was extended by 2 hours compared with Example 2. Next, this pulverized product was separated into a powder A of 600 μm or more and less than 1.0 mm, a powder B of 150 μm or more and 400 μm or less, and a powder C of 44 μm or less using an automatic sieving machine.

Then, by weight ratio, the powder A was adjusted to 25%, the powder B to 74.7%, and the powder C to 0.3% to obtain silicon carbide powder. This initial bulk density of the silicon carbide powder is 1.47 g / cm ^3, a tap bulk density 1.50 g / cm ^3, Blaine specific surface area of 420 cm ² / g, the following proportions of the powder particle size 44μm in 0.3% there were.

  The silicon carbide powder was subjected to acid cleaning and drying in the same manner as in Example 1, and then the impurity content was measured.

  Next, using this silicon carbide powder as a raw material, a lump of silicon carbide single crystal having a thickness of 20 mm was obtained in the same manner as in Example 1. In the obtained silicon carbide single crystal, it was confirmed that dislocation defects were generated, although no stacking defects that were at least unsuitable as a power semiconductor substrate material were generated.

(Comparative Example 3)
In Comparative Example 3, the silicon carbide powder obtained by pulverizing the lump in Example 1 was pulverized to 2 mm or less using a jaw crusher, a top grinder, and a ball mill, as in Comparative Example 2. However, the operation time of the ball mill was extended by 1 hour compared with Comparative Example 2. Such initial bulk density of silicon carbide powder of the as-milled in 1.51 g / cm ^3, a tap bulk density 1.55 g / cm ^3, Blaine specific surface area of 450 cm ² / g, the following powder particle size 44μm The ratio of was 2.5%.

  The silicon carbide powder was subjected to acid cleaning and drying in the same manner as in Example 1, and then the impurity content was measured.

  Next, using this silicon carbide powder as a raw material, a lump of silicon carbide single crystal having a thickness of 20 mm was obtained in the same manner as in Example 1. It was confirmed that the obtained silicon carbide single crystal had at least stacking faults and dislocation defects that were inappropriate as a power semiconductor substrate material.

(Comparative Example 4)
In Comparative Example 4, the silicon carbide powder obtained by pulverizing the lump in Example 1 was pulverized to 2 mm or less using a jaw crusher, top grinder, and jet mill in the same manner as in Comparative Example 1. However, when pulverizing with a jet mill, the pulverization air was set at a lower pressure than Comparative Example 1. The silicon carbide powder as crushed as described above has an initial bulk density of 0.79 g / cm ³ , a tap bulk density of 0.82 g / cm ³ , a Blaine specific surface area of 340 cm ² / g, and a particle size of 44 μm or less. The ratio of was 2.6%.

  The silicon carbide powder was subjected to acid cleaning and drying in the same manner as in Example 1, and then the impurity content was measured.

  Next, using this silicon carbide powder as a raw material, a lump of silicon carbide single crystal having a thickness of 20 mm was obtained in the same manner as in Example 1. It was confirmed that the obtained silicon carbide single crystal had at least stacking faults and dislocation defects that were inappropriate as a power semiconductor substrate material.

Claims (4)

Initial bulk density is 0.85 g / cm ³ or more and 1.75 g / cm ³ or less, tap bulk density is 0.9 g / cm ³ or more and 1.8 g / cm ³ or less, and Blaine specific surface area is 300 cm ² / g or more and 400 cm ² / g or less of silicon carbide powder,
The ratio of the silicon carbide powder having a particle size range exceeding 44 μm and not more than 2000 μm is 98.5% or more, and the ratio of the silicon carbide powder having a particle size range of 44 μm or less is 1.5% or less. Silicon powder.   The silicon carbide powder according to claim 1, wherein each content of boron, phosphorus, aluminum, iron, and titanium is 1.0 ppm or less. Silicon carbide powder according to claim 1 or 2 the difference between the initial bulk density and tapped bulk density is equal to or less than 0.05 g / cm ³ or more 0.1 g / cm ^3.   A silicon carbide single crystal produced by filling a silicon carbide powder according to any one of claims 1 to 3 into a container as a raw material and sublimating the silicon carbide powder to produce a silicon carbide single crystal. Manufacturing method.