JP5171571B2 - Method for producing silicon carbide single crystal - Google Patents

Description

  The present invention relates to a method for manufacturing a silicon carbide single crystal, and more particularly, to a method for manufacturing a silicon carbide single crystal that has few crystal defects such as micropipes and screw dislocations and that is hardly mixed with different polymorphic crystals and different orientation crystals.

  Silicon carbide is attracting attention as a small and high-power electronic device material such as a semiconductor because it has a larger band gap and is superior in dielectric breakdown characteristics, heat resistance, radiation resistance, and the like compared to silicon. In addition, silicon carbide has attracted attention as an optical device material because it has excellent bonding properties with other compound semiconductors having excellent optical characteristics. Among such silicon carbide crystals, a silicon carbide single crystal has an advantage that it is particularly excellent in uniformity of characteristics in a wafer when applied to a device such as a wafer, as compared with a silicon carbide polycrystal.

  As a method for producing this silicon carbide single crystal, a sublimation method at a high temperature is usually used by using silicon carbide powder as a raw material for sublimation. In the production of the silicon carbide single crystal by the sublimation method, the crucible in which the seed crystal filled with the silicon carbide raw material powder is placed in an inert gas atmosphere is decompressed, and the entire apparatus is heated to 1800 to 2400 ° C. The sublimation gas generated when the silicon carbide powder is decomposed and sublimated by heating reaches the surface of the seed crystal held in the growth temperature range and grows as a single crystal.

However, as the temperature rises, raw material silicon carbide generates vapors such as Si, Si ₂ C, SiC ₂ , and SiC that contribute to crystal growth, and at the same time, impurities fine particles contained in the sublimation raw materials, crystalline interfering fine particles, etc. Will also float in the crucible. These impurity fine particles adhere to the surface of the single crystal on which the seed crystal grows, which is provided substantially opposite to the sublimation raw material in the crucible, causing micropipes and dislocations in the grown silicon carbide single crystal. It is said that there is.

  On the other hand, in order to produce a seed crystal from a silicon carbide single crystal, a forming process is performed by grinding, polishing, cleaning, chemical treatment, etc., but disturbance such as a deteriorated layer generated during the processing remains on the surface of the seed crystal. ing. Since the silicon carbide is chemically stable, this work-affected layer is difficult to remove without an appropriate etchant. For this reason, in the normal sublimation method, crystal defects such as micropipes and screw dislocations are caused due to crystal defects on the surface of the seed crystal.

As a technique for suppressing the occurrence of crystal defects such as micropipes and screw dislocations, for example, in Japanese Patent Laid-Open No. 5-262599, a seed crystal having a plane substantially perpendicular to the {0001} plane is used. A method of growing a silicon carbide single crystal in a direction perpendicular to the above has been proposed. It has also been reported that when a silicon carbide single crystal is grown in a direction perpendicular to the <0001> direction, the grown crystal completely inherits the polytype structure of the seed crystal.
JP-A-5-262599

  The present invention has been made in view of the above-described conventional circumstances, and by growing using a growth end face type that does not have a work-affected layer, there are few crystal defects such as micropipes and screw dislocations, and many different types. An object of the present invention is to provide a method for producing a silicon carbide single crystal with almost no inclusion of shaped crystals or different orientation crystals.

  In particular, an object of the present invention is to provide a method for producing a silicon carbide single crystal with few crystal defects and almost no inclusion of different types of polymorphic crystals or different orientation crystals in a growth method using a growth end face type that does not have a work-affected layer. And

  In order to achieve the above object, a method for producing a silicon carbide single crystal according to the present invention includes a second sublimation raw material that is substantially opposite to a sublimation raw material in the reaction container. A method for producing a silicon carbide single crystal in which a seed crystal of a silicon carbide single crystal is disposed at an end, and a sublimated raw material for sublimation is recrystallized on the seed crystal to grow a silicon carbide single crystal. The crystal has a surface having a predetermined off-angle from the {0001} plane as a growth end surface, and the growth end surface has a convex shape having a predetermined curvature. In the growth of the silicon carbide single crystal, the seed The crystal growth is performed at a growth rate at which the deviation of the growth axis of the c-plane facet that performs growth by two-dimensional nucleation of the growth end face of the crystal or spiral growth by screw dislocation is within an allowable range.

  The method for producing a silicon carbide single crystal according to the present invention is characterized in that a speed at which the growth axis of the c-plane facet is shifted is less than 0.04 [mm / h].

  In the method for producing a silicon carbide single crystal of the present invention, the sublimation raw material is accommodated in the first end portion in the reaction container, and the silicon carbide single crystal is disposed in the second end portion substantially opposed to the sublimation raw material in the reaction container. A method for producing a silicon carbide single crystal in which a seed crystal of crystal is arranged, and a sublimation raw material that has been sublimated is recrystallized on the seed crystal to grow a silicon carbide single crystal, wherein the seed crystal is {0001 } Has a surface having a predetermined off-angle from the surface as a growth end surface, and the growth end surface has a convex shape having a predetermined curvature, and in the growth of the silicon carbide single crystal, the growth end surface of the seed crystal Crystal growth is performed at a growth rate such that the deviation of the boundary between the c-face facet region that performs growth by two-dimensional nucleation or spiral growth by screw dislocation and the step flow growth region other than the c-face facet that performs step flow growth is within an allowable range. Features to do To.

  The method for producing a silicon carbide single crystal of the present invention is characterized in that the growth rate of the silicon carbide single crystal is less than 0.2 [mm / h].

  According to the method for producing a silicon carbide single crystal of the present invention having the above characteristics, in a method for producing a silicon carbide single crystal by a sublimation method in which a sublimated raw material for sublimation is recrystallized on a seed crystal to grow a silicon carbide single crystal. A seed crystal having a surface having a predetermined off angle from the (0001) plane as a growth end surface and a convex shape having a predetermined curvature on the growth end surface is used as a seed crystal. Since crystal growth is performed at a growth rate in which the deviation of the growth axis of the c-plane facet that performs growth by two-dimensional nucleation of the growth end face of the crystal or spiral growth by screw dislocation is within an allowable range, In addition to suppressing the generation of new two-dimensional nuclei (growth axes) at the surface, the movement of c-plane facets is suppressed to suppress the occurrence of step bunching, resulting in the occurrence of defects such as polymorphs and micropipes. It is possible to obtain a high-quality silicon carbide single crystal which suppresses.

  Further, according to the method for producing a silicon carbide single crystal of the present invention having the above characteristics, the c-plane performs growth by two-dimensional nucleation of the growth end face of the seed crystal or spiral growth by screw dislocation in the growth process of the silicon carbide single crystal. Since the crystal growth is performed at a growth rate at which the boundary deviation between the facet region and the step flow growth region other than the c-plane facet that performs the step flow growth is within an allowable range, a new 2 in the c-plane facet region is obtained. In addition to suppressing the generation of dimensional nuclei (growth axis), the movement of the boundary of the growth mode (the boundary between the c-face facet region and the step flow growth region) is suppressed, thereby suppressing the occurrence of step bunching. A high-quality silicon carbide single crystal that suppresses the occurrence of defects such as contamination and micropipes can be obtained.

  Hereinafter, the best mode for carrying out the method for producing a silicon carbide single crystal of the present invention will be described in detail with reference to the drawings.

(Silicon carbide single crystal manufacturing equipment)
As shown in FIG. 1, as an embodiment of a manufacturing apparatus used for manufacturing a silicon carbide single crystal, a reaction vessel main body 12 that can accommodate a sublimation raw material 40 and a lid that is detachably provided on the reaction vessel main body 12. First heating that forms a sublimation atmosphere so that the sublimation raw material 40 can be sublimated, and is arranged in a state of being wound around the outer periphery of the portion where the sublimation raw material 40 is accommodated. The first induction heating coil 20 as a means and the sublimation raw material 40 disposed in a state of being wound around the outer periphery of the portion where the seed crystal 50 is disposed and sublimated by the first induction heating coil 20 is a silicon carbide single crystal. Second induction heating as a second heating means for forming a recrystallization atmosphere so that recrystallization is possible only in the vicinity of the seed crystal 50 and recrystallizing the sublimation raw material 40 on the seed crystal 50 of the silicon carbide single crystal. Coil 21 and first invitation An induction current can be passed between the heating coil 20 and the second induction heating coil 21, and interference between the first induction heating coil 20 and the second induction heating coil 21 is prevented by passing the induction current. And an interference prevention coil 22 as an interference prevention means.

  There is no restriction | limiting in particular as the crucible 10, The crucible 10 provided with the reaction container main body 12 and the cover part 11 selected suitably from well-known things can be used. The lid 11 is preferably one that can be attached to and detached from the reaction vessel main body 12. This is because the sublimation raw material 40 can be easily charged and the grown single crystal can be easily taken out. The reaction vessel main body 12 and the lid portion 11 may be designed to be detachable by fitting, screwing or the like, but those by screwing are preferable.

  The material of the reaction vessel main body 12 and the lid portion 11 constituting the crucible 10 is not particularly limited and can be appropriately selected from known materials, but those made of graphite are particularly preferable. In the reaction container, it is preferable that at least the surface of the inner peripheral side surface of the lid portion 11 (or a sealing portion described later) at the second end portion is glassy carbon or amorphous carbon. This is because recrystallization of silicon carbide is suppressed at least on the surface of the inner peripheral side surface. In this case, it is more preferable that the surface of the portion including the peripheral edge of the bottom where the seed crystal 50 is installed at the second end is glassy carbon or amorphous carbon.

  Although there is no restriction | limiting in particular as a site | part in which the sublimation raw material 40 is accommodated, It is preferable that it is an edge part substantially opposite to the edge part which can arrange | position the seed crystal 50 of a silicon carbide single crystal. In this case, the inside of the reaction vessel has a cylindrical shape, but the cylindrical axis may be linear or curved. The cross-sectional shape perpendicular to the axial direction of the cylindrical shape may be circular or polygonal. Preferable examples of the circular shape include those having a straight axis and a circular cross section perpendicular to the axial direction.

  When two ends exist in the reaction vessel, the sublimation raw material 40 is accommodated on the first end side, and the seed crystal 50 of the silicon carbide single crystal is disposed on the second end side. There is no restriction | limiting in particular as a shape of a 1st end part, A planar shape may be sufficient, and the structure (for example, convex part etc.) for promoting soaking | uniform-heating may be provided suitably.

  In the reaction vessel, the second end side is preferably designed to be detachable. Specifically, the second end portion is designed so that the lid portion 11 can be attached to and detached from the reaction vessel main body 12, and the sealing portion described later can seal the joint portion between the reaction vessel main body 12 and the lid portion 11. It is preferable that the sealing portion is designed to be housed inside the reaction container when the lid 11 is mounted on the reaction container. In this case, it is advantageous in that the grown silicon carbide single crystal can be easily separated from the reaction vessel simply by removing the lid 11 attached to the second end.

  There is no restriction | limiting in particular as positional relationship of a 1st end part and a 2nd end part, According to the objective, it can select suitably. In this case, it is preferable that the first end portion is the lower end portion and the second end portion is the upper end portion, that is, the first end portion and the second end portion are positioned in the direction of gravity. This is because sublimation of the sublimation raw material 40 is performed smoothly, and the growth of the silicon carbide single crystal is performed in a state where no extra load is applied downward, that is, in the direction of gravity.

  In addition, you may arrange | position the member formed with the material excellent in heat conductivity in order to perform sublimation of the sublimation raw material 40 efficiently, for example in the 1st end part side. As this member, for example, the outer periphery can be in close contact with the peripheral side surface portion in the reaction vessel, and the inside has an inverted frustum shape or an inverted frustum shape whose diameter gradually increases as it approaches the second end portion. A member etc. are mentioned suitably. The portion exposed to the outside of the reaction vessel may be provided with threading, a temperature measuring recess, etc., depending on the purpose, and the temperature measuring recess is on the first end side and the second end side. It is preferable that it is provided in at least one part.

  There is no restriction | limiting in particular as a material of reaction container, According to the objective, it can select suitably. What is formed with the material excellent in durability, heat resistance, heat conductivity, etc. is preferable. In addition to these requirements, those made of graphite are particularly preferred from the viewpoints of less contamination of polycrystals and polymorphs due to generation of impurities, and easy control of sublimation and recrystallization of the sublimation raw material 40. The reaction vessel may be formed of a single member or may be formed of two or more members, and can be appropriately selected according to the purpose. In the case of being formed of two or more members, the second end portion is preferably formed of two or more members, and the central portion of the second end portion and the outer peripheral portion thereof are formed of different members. It is more preferable in that a temperature difference or a temperature gradient can be formed. Specifically, in the reaction vessel, the inner region adjacent to the region where the silicon carbide single crystal is grown at the second end and the outer peripheral region located at the outer periphery of the inner region are formed of different members, and It is particularly preferable that one end of the member forming the inner region is in contact with a sealing portion provided in the reaction vessel and the other end is exposed to the outside of the reaction vessel.

  In this case, when the second end is heated from the outside, the outside region is easily heated, but the inside region is hardly heated due to contact resistance with the outside region. Therefore, a temperature difference occurs between the outer region and the inner region, and the temperature of the inner region is kept slightly lower than that of the outer region. As a result, silicon carbide can be recrystallized more easily in the inner region than in the outer region. Furthermore, since the other end of the member forming the inner region is exposed to the outside of the reaction vessel, the inner region is likely to dissipate heat to the outside of the reaction vessel, so that the inner region is more silicon carbide than the outer region. Recrystallization can easily occur. The form in which the other end of the member forming the inner region is exposed to the outside of the reaction vessel is not particularly limited, and the inner region is the bottom surface and is continuously or discontinuously toward the outside of the reaction vessel. Examples include a shape whose diameter changes, that is, a shape that increases or decreases.

  Specific examples of such a shape include a columnar shape having an inner region as a bottom surface, such as a columnar shape, a prismatic shape, etc., and a columnar shape is preferable, and a frustum shape having an inner region as a bottom surface, such as a truncated cone. Shape, truncated pyramid shape, inverted truncated cone shape, inverted truncated pyramid shape and the like, and the inverted truncated cone shape is preferable. In addition, in order to improve the thermal contact between one end of the member forming the inner region and the sealing portion provided in the reaction vessel, the contact portion is adhered, or the convex portion or the uneven shape is formed on one side or both sides of the contact portion. Providing a portion or the like is also preferable in terms of increasing heat dissipation in the inner region and facilitating recrystallization of silicon carbide. It goes without saying that the same idea is also effective when the second end is formed of a single member.

  The reaction vessel is preferably surrounded by a heat insulating material or the like. In this case, a heat insulating material or the like is provided in the approximate center of the first end portion (sublimation raw material storage portion) and the second end portion (seed crystal placement portion) in the reaction vessel for the purpose of forming a temperature measurement window. Preferably not. In addition, when a temperature measuring window is provided in the approximate center of the first end (sublimation raw material container), a graphite cover member or the like is further provided to prevent the insulation powder from falling. It is preferable.

  The reaction vessel is preferably placed in a quartz tube. In this case, it is preferable in that the loss of heating energy for sublimation and recrystallization of the sublimation raw material 40 is small. In addition, a high purity product is available for the quartz tube, and the use of a high purity product is advantageous in that there is little mixing of metal impurities.

  The first induction heating coil 20 is not particularly limited as long as it can be heated by energization to form a sublimation atmosphere so that the sublimation raw material 40 can be sublimated, and examples thereof include a coil capable of induction heating. The first induction heating coil 20 is disposed in a state of being wound around the outer periphery of the portion of the crucible 10 in which the sublimation raw material 40 is accommodated.

  The second induction heating coil 21 forms a recrystallization atmosphere so that the sublimation raw material 40 sublimated by the first induction heating coil 20 can be recrystallized only in the vicinity of the silicon carbide seed crystal 50. There is no particular limitation as long as 40 can be recrystallized on the silicon carbide seed crystal 50, and examples thereof include a coil capable of induction heating. Second induction heating coil 21 is arranged in a state of being wound around the outer periphery of the portion of silicon crucible 10 where silicon carbide seed crystal 50 is arranged.

  The interference prevention coil 22 is disposed between the first induction heating coil 20 and the second induction heating coil 21 for the purpose of efficient growth of the silicon carbide single crystal. When induction heating by the first induction heating coil 20 and the second induction heating coil 21 is performed simultaneously, a dielectric current flows through the interference prevention coil 22, and the interference prevention coil 22 can minimize and prevent interference between the two. Because. The interference preventing coil 22 is not particularly limited as long as it has a function of preventing interference between the first induction heating coil 20 and the second induction heating coil 21. The interference preventing coil 22 is preferably designed so as not to be heated by an induced current flowing through itself, more preferably one that can be cooled by itself, and particularly preferably one that can circulate a cooling medium such as water. In this case, even if the induction current in the first induction heating coil 20 and the second induction heating coil 21 flows through the interference prevention coil 22, the interference prevention coil 22 is not heated and does not cause damage or malfunction of peripheral parts. Is preferable. There are no particular restrictions on the number of turns of the interference preventing coil 22 that is wound, and the number of turns depends on the type of the first heating means and the second heating means, the amount of current passed through them, etc. Even a single degree is sufficient.

  In the silicon carbide single crystal manufacturing apparatus according to the present embodiment, a sublimation atmosphere is formed so that the first induction heating coil 20 can sublimate the sublimation raw material 40, and the sublimation raw material 40 is sublimated. The second induction heating coil 21 forms a recrystallization atmosphere so that the sublimation raw material 40 sublimated by the first induction heating coil 20 can be recrystallized only in the vicinity of the seed crystal 50, and the sublimation raw material 40. Is recrystallized on the seed crystal 50. For this reason, in the growing silicon carbide single crystal, in the whole growth process, the entire surface of the growth surface is maintained in a convex shape toward the growth direction, and the concave portion depressed on the lid portion 11 side is formed in a ring shape. There is no. Further, the silicon carbide polycrystal does not grow in a state in which it is in contact with the peripheral side surface portion in the reaction vessel main body 12. For this reason, when the grown silicon carbide single crystal is cooled to room temperature, stress based on the thermal expansion difference is not concentrated and applied from the silicon carbide polycrystal side to the silicon carbide single crystal side. No damage such as cracking occurs in the single crystal. As a result, various problems in the past, i.e., high-quality silicon carbide single crystals that are free from breakage such as cracks and that do not contain polycrystals, polymorphs, or crystal defects such as micropipes, can be produced efficiently and reliably. Can do.

  In addition, there is no restriction | limiting in particular as said 1st and 2nd heating means, According to the objective, it can select suitably. For example, induction heating means, resistance heating means and the like can be mentioned. Induction heating means are preferable from the viewpoint of easy temperature control, and among induction heating means, a coil capable of induction heating is preferable.

(Seed crystal)
Next, in the method for manufacturing a silicon carbide single crystal according to the present embodiment, the silicon carbide single crystal seed crystal 50 has a surface having a predetermined off angle from the (0001) plane as a growth end surface, and the growth An end face having a convex shape having a predetermined curvature is used. In the manufacture of a conventional silicon carbide single crystal, a silicon carbide single crystal wafer having a thickness of about 0.3 to 1.0 [mm] is used as a seed crystal. What was cut out with a predetermined thickness (about 3 to 5 [mm]) is used as a silicon carbide single crystal end face seed.

  Here, in FIG. 2, the off direction refers to a direction inclined from the <0001> axis (c-axis) direction indicated by n in the figure, and is the direction of a vector in which n is projected (projected) onto the (0001) plane. It is shown. In FIG. 2, the n-off direction coincides with the <11-20> axis direction. Further, the case where the off direction is shifted by α or α ′ degrees from the <11-20> direction is also shown in the drawing. The off-angle is an angle at which n is inclined from the <0001> axis (c-axis) direction indicated by β in the figure. That is, it indicates the off angle from the (0001) plane.

  By giving the growth surface a predetermined off-angle, it becomes possible to promote step flow growth, prevent polytypes due to the generation of two-dimensional nuclei, which is a problem during just surface growth, and a spiral whose Barker spectrum is <0001> Reduction effect of dislocation and MP can be expected.

  Further, by using a silicon carbide single crystal having the same shape as the temperature distribution in the crucible for the seed crystal 50, the c-plane facet position moves with the growth, so that the boundary between the c-plane facet region and the step flow growth region is reduced. Prevents quality degradation.

  Therefore, the convex shape on the growth end face of the seed crystal 50 of the silicon carbide single crystal needs to be a shape close to the temperature distribution in the crucible, and it is more preferable to use the growth end face grown in the same crucible.

(Raw material for sublimation)
Next, as the sublimation raw material 40, as long as it is silicon carbide, there are no particular limitations on the polymorph of the crystal, the amount used, its purity, its production method, and the like, and it can be appropriately selected according to the purpose. Examples of the crystal polymorph of the sublimation raw material 40 include 4H, 6H, 15R, and 3C. Among these, 6H and the like are preferable. These are preferably used alone, but may be used in combination of two or more.

  The amount of the sublimation raw material 40 used can be appropriately selected according to the size of the silicon carbide single crystal to be produced, the size of the reaction vessel, and the like. The purity of the sublimation raw material 40 is preferably high from the viewpoint of preventing polycrystals and polymorphs from being mixed into the silicon carbide single crystal to be produced as much as possible. Each content is preferably 0.5 [ppm] or less. Here, the content of the impurity element is an impurity content by chemical analysis, and has only a meaning as a reference value. In practice, the impurity element is uniformly distributed in the silicon carbide single crystal. The evaluation differs depending on whether it is localized or unevenly distributed. Here, the “impurity element” refers to a group 1 to group 17 element in the periodic table of the 1989 IUPAC inorganic chemical nomenclature revised edition and has an atomic number of 3 or more (provided that carbon atom, oxygen atom and silicon atom are Element). Further, in order to impart n-type or p-type conductivity to the growing silicon carbide single crystal, when a dopant element such as nitrogen or aluminum is intentionally added, these are also excluded.

  The silicon carbide powder as the sublimation raw material 40 includes, for example, at least one silicon compound as a silicon source, at least one organic compound that generates carbon by heating, and a polymerization catalyst or a crosslinking catalyst as a carbon source. It is obtained by firing in a non-oxidizing atmosphere a powder obtained by dissolving and drying in.

  As the silicon compound, a liquid one and a solid one can be used together, but at least one kind is selected from a liquid one.

  As the liquid, alkoxysilane and alkoxysilane polymers are preferably used. Examples of the alkoxysilane include methoxysilane, ethoxysilane, propoxysilane, butoxysilane and the like, and among these, ethoxysilane is preferable in terms of handling. The alkoxysilane may be any of monoalkoxysilane, dialkoxysilane, trialkoxysilane, and tetraalkoxysilane, but tetraalkoxysilane is preferable. Examples of the alkoxysilane polymer include a low molecular weight polymer (oligomer) having a polymerization degree of about 2 to 15 and a silicate polymer. An example is a tetraethoxysilane oligomer.

  Examples of the solid material include silicon oxides such as SiO, silica sol (a colloidal ultrafine silica-containing liquid containing OH groups and alkoxyl groups inside), and silicon dioxide (silica gel, fine silica, quartz powder).

  A silicon compound may be used individually by 1 type, and may use 2 or more types together. Among the silicon compounds, an oligomer of tetraethoxysilane, a mixture of an oligomer of tetraethoxysilane and fine powder silica, and the like are preferable in terms of good homogeneity and handling properties. The silicon compound preferably has a high purity, and the content of each impurity in the initial stage is preferably 20 [ppm] or less, and more preferably 5 [ppm] or less.

  As an organic compound that generates carbon by heating, a liquid compound may be used alone, or a liquid compound and a solid compound may be used in combination. As the organic compound that generates carbon by heating, a residual carbon ratio is high, and an organic compound that is polymerized or cross-linked by a catalyst or heating is preferable, for example, a resin monomer such as phenol resin, furan resin, polyimide, polyurethane, polyvinyl alcohol, Prepolymers are preferred, and other liquid materials such as cellulose, sucrose, pitch, and tar can be used. Among these, high-purity ones are preferable, phenol resins are more preferable, and resol type phenol resins are particularly preferable.

  The organic compound which produces carbon by heating may be used alone or in combination of two or more. The purity of the organic compound that generates carbon by heating can be appropriately selected according to the purpose, but when a high-purity silicon carbide powder is required, the organic compound does not contain 5 [ppm] or more of each metal. Is preferably used.

  The polymerization catalyst and the crosslinking catalyst can be appropriately selected according to the organic compound that generates carbon by heating. When the organic compound that generates carbon by heating is a phenol resin or furan resin, toluenesulfonic acid, toluenecarboxylic acid, acetic acid, oxalic acid is used. Acids such as acid, maleic acid and sulfuric acid are preferred, and maleic acid is particularly preferred.

  The ratio of carbon contained in the organic compound that produces carbon by heating and silicon contained in the silicon compound (hereinafter abbreviated as “C / Si ratio”) is obtained by carbonizing a mixture of both at 1000 [° C.]. Carbide intermediates are defined by elemental analysis. Stoichiometrically, the free carbon in the silicon carbide powder obtained when the C / Si ratio is 3.0 should be 0%. However, in practice, low C is caused by volatilization of the simultaneously generated SiO gas. Free carbon is generated at the / Si ratio. It is preferable to determine the blending ratio in advance so that the amount of free carbon in the obtained silicon carbide powder becomes an appropriate amount. Usually, in firing at 1600 [° C.] or higher near 1 atm, free carbon can be suppressed by setting the C / Si ratio to 2.0 to 2.5. When the C / Si ratio exceeds 2.5, free carbon increases remarkably. However, when the atmosphere pressure is fired at a low pressure or a high pressure, the C / Si ratio for obtaining pure silicon carbide powder varies, and in this case, it is not necessarily limited to the range of the C / Si ratio.

  The silicon carbide powder can also be obtained, for example, by curing a mixture of a silicon compound and an organic compound that generates carbon by heating.

  Examples of the curing method include a method of crosslinking by heating, a method of curing with a curing catalyst, a method of electron beam and radiation, and the like. The curing catalyst can be appropriately selected according to the type of organic compound that produces carbon by heating, and in the case of a phenol resin or furan resin, toluenesulfonic acid, toluenecarboxylic acid, acetic acid, oxalic acid, hydrochloric acid, Preferable examples include acids such as sulfuric acid and maleic acid, and amine acids such as hexamine. When these curing catalysts are used, the curing catalyst is dissolved or dispersed in a solvent. Examples of the catalyst include lower alcohols (eg, ethyl alcohol), ethyl ether, acetone and the like.

  The silicon carbide powder obtained as described above is baked for 30 to 120 [minutes] at 800 to 1000 [° C.] in a non-oxidizing atmosphere such as nitrogen or argon. The silicon carbide powder becomes a carbide by firing, and the carbide is fired at 1350 to 2000 [° C.] in a non-oxidizing atmosphere such as argon to produce a silicon carbide powder.

  The firing temperature and time can be appropriately selected according to the particle size of the silicon carbide powder to be obtained, and the temperature is 1600 to 1900 [° C.] in terms of more effective production of the silicon carbide powder. preferable. In addition, after baking, for the purpose of removing impurities and obtaining high-purity silicon carbide powder, for example, it is preferable to perform heat treatment at 2000 to 2400 [° C.] for 3 to 8 hours.

  Since the silicon carbide powder obtained as described above is non-uniform in size, it can be made into a desired particle size by pulverization, classification, and the like.

  The average particle size of the silicon carbide powder is preferably 10 to 300 [μm], more preferably 50 to 200 [μm]. If the average particle size is less than 10 [μm], sintering occurs rapidly at the sublimation temperature of silicon carbide for growing a silicon carbide single crystal, that is, 1800 to 2700 [° C.], so the sublimation surface area is small. When the silicon carbide powder is accommodated in the reaction vessel or when the pressure of the recrystallization atmosphere is changed to adjust the growth rate, the silicon carbide powder may be slowed. It becomes easy to scatter. On the other hand, when the average particle diameter exceeds 300 [μm], the specific surface area of the silicon carbide powder itself becomes small, so that the growth of the silicon carbide single crystal may also be slow.

  Examples of the silicon carbide powder include 4H, 6H, 15R, and 3C. Among these, 6H is preferable. These are preferably used alone, but may be used in combination of two or more.

  Note that nitrogen or aluminum can be introduced into the silicon carbide single crystal grown using the silicon carbide powder for the purpose of imparting n-type or p-type conductivity, respectively. In some cases, it may be uniformly mixed with a silicon source, a carbon source, an organic substance consisting of a nitrogen source or an aluminum source, and a polymerization or crosslinking catalyst. At this time, for example, when an organic substance composed of a carbon source such as a phenol resin and a nitrogen source such as hexamethylenetetramine and a polymerization or crosslinking catalyst such as maleic acid are dissolved in a solvent such as ethanol, tetraethoxysilane is dissolved. It is preferable to sufficiently mix with a silicon source such as an oligomer of

  As the organic substance composed of a nitrogen source, a substance that generates nitrogen by heating is preferable. For example, a polymer compound (specifically, polyimide resin, nylon resin, etc.); organic amine (specifically, hexamethylenetetramine) , Ammonia, triethylamine, and the like, and compounds and salts thereof). Among these, hexamethylenetetramine is preferable. Further, a phenol resin synthesized using hexamine as a catalyst and containing 2.0 [mmol] or more of nitrogen derived from the synthesis step with respect to 1 g of the resin can also be suitably used as an organic substance composed of a nitrogen source. These organic substances composed of a nitrogen source may be used alone or in combination of two or more. In addition, there is no restriction | limiting in particular as an organic substance which consists of aluminum sources, According to the objective, it can select suitably.

  As the addition amount of the organic substance composed of the nitrogen source, when the silicon source and the carbon source are added simultaneously, it is preferable that 1 [mmol] or more of nitrogen is contained per 1 g of the silicon source. g]] is preferably 80 to 1000 [μg].

  More specific sublimation raw materials 40 in the production of a silicon carbide single crystal are listed as follows. As a sublimation raw material 40, at least one selected from high-purity alkoxysilane and alkoxysilane polymer is used as a silicon source, and a high-purity organic compound that generates carbon by heating is used as a carbon source, and these are uniformly mixed. It is preferable to use silicon carbide powder obtained by heating and firing the mixture obtained in this manner in a non-oxidizing atmosphere. As a sublimation raw material 40, a high-purity alkoxysilane is used as a silicon source, a high-purity organic compound that generates carbon by heating is used as a carbon source, and a mixture obtained by uniformly mixing them is heated in a non-oxidizing atmosphere. It is preferable to use silicon carbide powder obtained by firing. Further, as a sublimation raw material 40, a high-purity alkoxysilane and a polymer of high-purity alkoxysilane are used as a silicon source, and a high-purity organic compound that generates carbon by heating is used as a carbon source. It is preferable to use silicon carbide powder obtained by heating and firing the obtained mixture in a non-oxidizing atmosphere. Further, as a sublimation raw material 40, at least one selected from the group consisting of high-purity methoxysilane, high-purity ethoxysilane, high-purity propoxysilane, and high-purity butoxysilane is used as a silicon source, and carbon is generated by heating. It is preferable to use silicon carbide powder obtained by heating and firing a mixture obtained by uniformly mixing these high purity organic compounds as a carbon source in a non-oxidizing atmosphere. Further, the sublimation raw material 40 is at least selected from the group consisting of high-purity methoxysilane, high-purity ethoxysilane, high-purity propoxysilane, high-purity butoxysilane, and polymers having a polymerization degree of 2 to 15. Silicon carbide powder obtained by heating and calcining a mixture obtained by uniformly mixing these, using a high purity organic compound that produces carbon by heating as one type of silicon source and heating them in a non-oxidizing atmosphere Is preferably used. The sublimation raw material 40 is selected from the group consisting of high-purity monoalkoxysilane, high-purity dialkoxysilane, high-purity trialkoxysilane, high-purity tetraalkoxysilane, and polymers having a polymerization degree of 2 to 15 A high purity organic compound that generates carbon by heating is used as a carbon source, and a mixture obtained by uniformly mixing these is heated and fired in a non-oxidizing atmosphere. It is preferable to use silicon carbide powder. Furthermore, it is preferable that the silicon source is a tetraalkoxysilane polymer and the carbon source is a phenol resin. It is preferable that each content of the impurity element of the silicon carbide powder is 0.5 [ppm] or less.

(Growth method of silicon carbide single crystal)
Next, a silicon carbide single crystal manufacturing method using the silicon carbide single crystal manufacturing apparatus of FIG. 1 will be described.

(A) First, the above-mentioned sublimation raw material 40 is accommodated in the first end portion in the reaction vessel.
(B) Next, a seed crystal 50 of a silicon carbide single crystal is disposed at the second end portion substantially opposed to the sublimation raw material 40 in the reaction vessel. As the seed crystal 50 of the silicon carbide single crystal, the polymorph, size, etc. of the crystal can be appropriately selected according to the purpose. As the polymorph of the crystal, the same polymorph as that of the silicon carbide single crystal to be obtained is usually selected.
(C) A sublimation atmosphere is formed, and the sublimated raw material 40 is recrystallized on the seed crystal 50 to grow a silicon carbide single crystal. The growth of the silicon carbide single crystal is performed on the seed crystal 50 of the silicon carbide single crystal disposed on the lid portion 11 (sealing portion) attached to the second end of the reaction vessel. In order to recrystallize and grow the silicon carbide single crystal on the seed crystal 50, the temperature is lower than the temperature at which the sublimation raw material 40 is sublimated, and the sublimated raw material 40 can be recrystallized only in the vicinity of the seed crystal 50. It is preferable to form such a recrystallization atmosphere. In other words, in the radial direction of the surface on which the seed crystal 50 is disposed, it is preferable to form an atmosphere that has a temperature distribution such that the temperature decreases as it approaches the center (center of the inner region).

  The recrystallization atmosphere can be suitably formed by the second induction heating coil 21 as the second heating means. Such a second induction heating coil 21 is arranged on the second end side of the reaction vessel, and the sublimation raw material 40 sublimated by the first heating means can be recrystallized only in the vicinity of the seed crystal 50 of the silicon carbide single crystal. Then, a recrystallization atmosphere is formed so that the sublimation raw material 40 is recrystallized on the silicon carbide single crystal seed crystal 50.

  The number of turns of the second induction heating coil 21 is not particularly limited, and is determined so as to optimize the heating efficiency and temperature efficiency depending on the distance from the first induction heating coil 20, the material of the reaction vessel, and the like. Can do. The amount of the induction heating current that is passed through the second induction heating coil 21 can be appropriately determined in relation to the amount of the induction heating current that is passed through the first heating means. The relationship between the two is preferably set so that the current value of the induction heating current in the first heating means is larger than the current value of the induction heating current in the second induction heating coil 21. In this case, it is advantageous in that the temperature of the recrystallization atmosphere in the vicinity of the seed crystal 50 is maintained lower than the temperature of the atmosphere in which the sublimation raw material 40 is sublimated, and recrystallization is easily performed. In addition, the current value of the induction heating current in the second induction heating coil 21 is preferably controlled so as to decrease continuously or stepwise as the diameter of the growing silicon carbide single crystal increases. In this case, since the heating amount by the second induction heating coil 21 is controlled to be small as the silicon carbide single crystal grows, recrystallization is performed only in the vicinity of the continuously growing silicon carbide single crystal. It is advantageous in that the formation of polycrystals is effectively suppressed.

  Since the second induction heating coil 21 can be controlled independently of the first induction heating coil 20, the heating amount of the second induction heating coil 21 is appropriately adjusted according to the growth rate of the silicon carbide single crystal. By doing so, a preferable growth rate can be maintained throughout the entire growth process of the silicon carbide single crystal. The temperature of the recrystallization atmosphere formed by the second induction heating coil 21 is preferably 30 to 300 [° C.] lower than the temperature of the sublimation atmosphere formed by the first heating means, and 30 to 100 [° C.]. More preferably, it is low. The pressure of the recrystallization atmosphere formed by the second induction heating coil 21 is preferably 1 to 5 [Torr] (1330 to 13300 [Pa]). Note that when this pressure condition is used, it is not necessary to heat while maintaining the reduced pressure, but to reduce the pressure after heating to the set temperature and adjust the pressure condition to be within a predetermined numerical range. preferable.

  The recrystallization atmosphere is preferably an inert gas atmosphere such as argon gas.

(Growth of silicon carbide single crystal)
Next, the growth of the silicon carbide single crystal according to this embodiment will be described. First, the silicon carbide single crystal is recrystallized and grown in the following form. A silicon carbide single crystal is grown through the entire growth process while keeping the entire growth surface in a convex shape. In this case, the concave portion recessed inside the single crystal is not formed in a ring shape over the entire growth surface of the silicon carbide single crystal.

  As the shape of the growing silicon carbide single crystal, the entire growth surface is convex in the growth direction side, and the first end (sublimation raw material 40 accommodating portion) and the second end are opposed to each other. The entire surface of the growth surface is convex toward the sublimation raw material 40 side, that is, toward the first end portion side. In this case, polycrystals and polymorphs are often mixed, and this is preferable in that there is no depressed portion on the second end side, where stress due to a difference in thermal expansion is likely to be concentrated.

  Further, the shape of the silicon carbide crystal including the silicon carbide single crystal is preferably substantially chevron toward the sublimation raw material 40 side, that is, toward the first end portion, and is substantially chevron with a gradually decreasing diameter. Is more preferable. In other words, a silicon carbide crystal including a silicon carbide single crystal is grown while maintaining a substantially chevron shape in which the diameter gradually decreases toward the sublimation raw material 40 side throughout the entire growth process. In addition, silicon carbide polycrystals and polymorphs may be mixed in the base portion of the silicon carbide crystal having a substantially chevron shape, that is, the outer peripheral portion. This mixing may cause the thickness, size, shape, etc. of the seed crystal 50 to be mixed. And the combination of conditions with the amount of heating by the second induction heating coil 21 can prevent its occurrence. It is preferable to prevent silicon carbide polycrystals and polymorphs from being mixed, because silicon carbide crystals containing silicon carbide can be made of only a silicon carbide single crystal.

  Next, the growth of the silicon carbide single crystal is performed at the following growth rate. That is, in the growth of the silicon carbide single crystal, the deviation of the growth axis of the c-plane facet that performs growth by two-dimensional nucleation of the growth end face of the seed crystal 50 of the silicon carbide single crystal or spiral growth by screw dislocation is within an allowable range. Crystal growth is performed at a growth rate. Here, the speed at which the growth axis of the c-plane facet is shifted is preferably less than 0.04 [mm / h].

  Alternatively, the boundary between the c-face facet region in which the growth end face of the seed crystal 50 of the silicon carbide single crystal 50 is grown by two-dimensional nucleation or the spiral growth by screw dislocation and the step flow growth region other than the c-face facet in which step flow growth is performed Crystal growth is performed at a growth rate at which the deviation is within an allowable range. Here, it is preferable that the allowable range of the deviation of the boundary between the c-plane facet region and the step flow growth region is less than 5 [mm]. More specifically, the growth rate of the silicon carbide single crystal is preferably less than 0.2 [mm / h].

  Here, the growth of the silicon carbide single crystal according to the present embodiment will be conceptually described with reference to the explanatory views of FIGS. 3, 4, and 5. FIGS. 3A and 3B are explanatory diagrams schematically illustrating the formation of c-plane facets, and FIG. 3B conceptually illustrating the c-plane facet region and the step flow growth region on the growth end face of the seed crystal 50 of the silicon carbide single crystal. FIG. 4 is an explanatory diagram schematically illustrating (a) spiral growth due to screw dislocation in the c-plane facet region, and (b) a description schematically illustrating step flow growth in the step flow growth region. FIGS. 5A and 5B are explanatory views conceptually explaining the occurrence of step bunching at the growth end face according to the present invention and FIG.

  When an end face having an off angle β from the (0001) face (c face) of the silicon carbide single crystal seed crystal 50 is used as a growth end face, as shown in FIG. Growth by two-dimensional nucleation or spiral growth by screw dislocation starts at a portion where the off-angles match, and a c-plane facet is formed. Here, the spiral growth by the screw dislocation means a step in which a step occurs from the occurrence of the screw dislocation as shown in FIG. Therefore, in the c-plane facet region (see FIG. 3B), in a substantially c-axis direction (that is, a direction inclined by the off angle β from the <0001> axis to the off direction (<11-20> axis direction)) The spiral growth due to the screw dislocation proceeds.

  On the other hand, in a region other than the C-plane facet, a step inclined by an off-angle β from the a-axis direction (horizontal direction in FIG. 3A) is formed, so that the terrace step kink (TSK) model ( Step flow growth (refer to FIG. 4B) is performed (growth in the lateral direction of steps by diffusion atoms on the terrace being bonded to the kink). That is, in the step flow growth region (see FIG. 3B), step flow growth proceeds in a substantially a-axis direction (that is, a direction tilted upward from the a-axis by the off angle β).

  That is, as shown in FIG. 4A, when the growth end face of the seed crystal 50 of the silicon carbide single crystal has a predetermined off angle, two different growth mode regions, that is, two-dimensional areas are formed on the growth end face. It is considered that a c-plane facet region that performs growth by nucleation or spiral growth by screw dislocation and a step flow growth region that performs step flow growth are formed.

  Conventionally, as a method for producing a silicon carbide single crystal, a silicon carbide seed crystal in which a surface having an off angle of less than 10 degrees from the {0001} plane (c-plane) is exposed as a seed crystal growth surface is sublimated. A silicon carbide single crystal has been grown on the growth surface. In this case, as the crystal growth proceeds and the growth end face becomes convex, the c-axis growth location (facet location) moves from the end side to the center side. For this reason, movement of the growth mode boundary (the boundary between the c-plane facet region and the step flow growth region) causes polymorphic contamination, and many step bunchings occur at the growth mode boundary, resulting in crystal defects. Many will occur.

  In contrast, in the method for producing a silicon carbide single crystal of the present invention, a silicon carbide single crystal end face seed is obtained by cutting the end face after growth, and the growth end face whose growth mode boundary position is determined is a seed crystal. In addition to the above, the growth rate is relatively slower than in the prior art, and the growth rate at which the deviation of the growth axis of the c-plane facet is within an allowable range, or between the c-plane facet region and the step flow growth region Crystal growth was performed at a growth rate at which the boundary deviation was within an allowable range. This suppresses the generation of new two-dimensional nuclei in the c-plane facet region, and suppresses the generation of step bunching by suppressing the movement of the growth mode boundary position, as shown in FIG. As a result, it was possible to obtain a high-quality silicon carbide single crystal that suppressed the occurrence of defects such as polymorphism and micropipes.

(Silicon carbide single crystal)
The silicon carbide single crystal has a crystal defect (pipe defect) optically detected nondestructively and is preferably 100 [piece / cm ² ] or less, more preferably 50 [piece / cm ² ] or less, more preferably 10 [Pieces / cm ² ] or less. The crystal defect can be detected as follows, for example. When the silicon carbide single crystal is illuminated with an appropriate amount of transmitted illumination in addition to reflected illumination, and the microscope focus is focused on the crystal defect (pipe defect) opening on the surface of the silicon carbide single crystal, Scanning the entire surface of the silicon carbide single crystal to obtain a microscopic image under conditions where the portion leading to the inside can be observed as a shadow that is weaker than the image of the aperture and connected to the aperture, By processing, it is possible to detect the pipe defect by extracting only the shape characteristic of the pipe defect and measuring the number thereof.

  In addition, according to the above detection, it is possible to accurately detect only pipe defects in a non-destructive manner from the presence of foreign matters adhering to the surface of the silicon carbide single crystal, and defects other than pipe defects such as polishing scratches and void defects. Moreover, even a minute pipe defect of, for example, about 0.35 [μm] can be accurately detected. On the other hand, conventionally, a method has been used in which a pipe defect portion is selectively etched by molten alkali and enlarged and detected. In this method, adjacent pipe defects are joined together by etching. As a result, there is a problem that a small number of pipe defects are detected.

  The total content of impurity elements in the silicon carbide single crystal is preferably 10 [ppm] or less.

(Use)
The silicon carbide single crystal obtained in this way has no crystal defects such as polycrystals, polymorphs, and micropipes, and is extremely high quality. Therefore, it has excellent dielectric breakdown characteristics, heat resistance, radiation resistance and the like, and is particularly preferably used for electronic devices such as semiconductor wafers, optical devices such as light emitting diodes, and power devices.

  EXAMPLES The present invention will be specifically described below with reference to examples and comparative examples. Needless to say, the present invention is not limited to the following examples. In the following description, a conventional silicon carbide single crystal is grown by using a silicon carbide seed crystal in which a surface having an off angle of less than 10 degrees from the (0001) plane is exposed as a seed crystal growth surface. The crystal production is called wafer growth using a wafer seed, the end face side after the growth is cut out as the silicon carbide single crystal end face seed, and the growth end face where the growth mode boundary position is determined is used as the seed crystal. The production of the silicon carbide single crystal according to the present invention, which is grown at a relatively slower growth rate than before, will be referred to as end face growth using end face seeds.

Example 1
A silicon carbide single crystal was manufactured using a silicon carbide single crystal manufacturing apparatus 1 shown in FIG.

  The sublimation raw material 40 is obtained by heating and baking a mixture obtained by uniformly mixing the above-described high-purity tetraethoxysilane polymer as a silicon source and resol-type phenol resin as a carbon source in an argon atmosphere. The obtained silicon carbide powder (6H (partly including 3C), average particle size was 100 [μm]).

  The silicon carbide single crystal seed crystal 50 is obtained by cutting the end face side of a silicon carbide single crystal obtained by wafer growth using a wafer seed, and in the vicinity of the growth mode boundary on the growth end face of the seed crystal 50. The step bunching was 11 [books]. (In other words, it means that the quality of the step bunching is reduced to 11 [pieces] due to the wafer growth using the wafer type without step bunching.) The seed crystal 50 has an off-angle of 8 [from the (0001) plane. It has a convex shape with a seed crystal thickness of about 3 [mm] and a diameter of 51 [mm].

  In the silicon carbide single crystal manufacturing apparatus 1, a current is passed through the first induction heating coil 20 to heat it, and the sublimation raw material 40 is heated to 2112 [° C.] with the heat, and then the pressure is increased in an argon gas atmosphere. 1 [Torr] (133.32 [Pa]). The sublimation raw material 40 was heated to a predetermined temperature (2112 [° C.]) and sublimated.

  Here, the lid 11 side is heated by the second induction heating coil 21, and the set temperature of the lid 11 by the second induction heating coil 21 is set to 2012 [° C.] lower than the sublimation raw material 40 side. . Since the sublimation raw material 40 is maintained in an atmosphere capable of recrystallization (1 [Torr]), silicon carbide is recrystallized only in the vicinity of the seed crystal 50 of the silicon carbide single crystal, and the growth rate is about 0.2. A silicon carbide single crystal grew below [mm / h].

  At this time, the growth of the silicon carbide single crystal was maintained in a convex shape toward the sublimation raw material 40 in the entire growth process, and no silicon carbide polycrystal was generated.

As a result, when the obtained silicon carbide single crystal was evaluated, the micropipe density (MPD) was 12.0 [cm ⁻² ], no step bunching was observed, and the crystal compared with the seed crystal 50 Quality improvement was confirmed.

(Example 2)
As the seed crystal 50 of the silicon carbide single crystal, a silicon carbide single crystal obtained by wafer growth using another wafer type different from that of the first embodiment is used. End face growth was performed using the same end face type. The step bunching in the vicinity of the growth mode boundary on the growth end face of the seed crystal 50 was 6 [pieces]. When the obtained silicon carbide single crystal was evaluated, the occurrence of step bunching was reduced to 2 [pieces], and an improvement in crystal quality was confirmed as compared with the seed crystal 50.

  From the evaluation results of Example 1 and Example 2, the end face side of the silicon carbide single crystal obtained by the end face growth using the end face seed was cut out and used as the seed crystal in the end face growth using the following end face seed It can be easily assumed that a silicon carbide single crystal of higher quality can be obtained stepwise by repeatedly performing end face growth using end face seeds.

  As described above, according to the method for producing a silicon carbide single crystal of the present invention, it has excellent dielectric breakdown characteristics, heat resistance, radiation resistance, etc., electronic devices such as semiconductor wafers, optical devices such as light emitting diodes, power devices, etc. In particular, it is possible to provide a method capable of efficiently and easily manufacturing a high-quality silicon carbide single crystal that suppresses the occurrence of defects such as polycrystals, polymorphs, and micropipes.

It is the schematic for demonstrating the initial state in the manufacturing method of a silicon carbide single crystal. It is explanatory drawing explaining the off angle and off direction of a hexagonal silicon carbide single crystal. (A) Explanatory drawing which explains typically formation of c plane facet, and (b) Explanatory drawing which explains notionally c plane facet field and a step flow growth field in a growth end face of a seed crystal of a silicon carbide single crystal. is there. (A) Explanatory drawing which illustrates typically spiral growth by the screw dislocation in the c-plane facet region, and (b) explanatory diagram schematically illustrates step flow growth in the step flow growth region. It is explanatory drawing which illustrates notionally generation | occurrence | production of the step bunching in the (a) this invention and the (b) conventional growth end surface.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Manufacturing apparatus 10 of a silicon carbide single crystal ... Crucible 11 ... Lid part 12 ... Reaction container main body 13 ... Circumferential side part 20 ... First induction heating coil (first heating means)
21 ... Second induction heating coil (second heating means)
22 ... Interference prevention coil (interference prevention means)
25 ... induction heating coil 30 ... quartz tube 31 ... support rod 40 ... raw material for sublimation 50 ... seed crystal of silicon carbide single crystal

Claims (2)

A sublimation raw material in which a sublimation raw material is contained in a first end portion in a reaction vessel and a seed crystal of a silicon carbide single crystal is disposed in a second end portion substantially opposite to the sublimation raw material in the reaction vessel, and is sublimated. A method for producing a silicon carbide single crystal in which a silicon carbide single crystal is grown by recrystallizing the seed crystal on the seed crystal ,
The seed crystal has a surface having a predetermined off angle from the (0001) plane as a growth end surface, and the growth end surface has a convex shape having a predetermined curvature,
In the growth of the silicon carbide single crystal, the rate at which the growth axis of the c-plane facet performing growth by two-dimensional nucleation of the growth end face of the seed crystal or spiral growth by screw dislocation is less than 0.04 [mm / h] A method for producing a silicon carbide single crystal, wherein crystal growth is performed at a growth rate of 2. The method for producing a silicon carbide single crystal according to claim 1 , wherein a growth rate of the silicon carbide single crystal is less than 0.2 [mm / h].

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