JP2013056807A - METHOD FOR PRODUCING SiC SINGLE CRYSTAL, AND SiC SINGLE CRYSTAL OBTAINED THEREBY - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide production of an SiC single crystal by a solution method capable of suppressing greatly void defects caused by entrainment of bubbles without using a special device, even in a pressurized condition with an atmospheric gas pressure of ≥0.1 MPa at a high temperature that enables SiC solution growth to be executed.SOLUTION: This invention relates to an SiC single crystal in which the void density of a crystal growth portion is ≤10,000/cm, and which is produced by keeping temporarily a solution temperature at a higher temperature by 50-300°C than a crystal growth temperature before dipping a seed crystal into the solution, when dipping the seed crystal of SiC into a solution containing Si and C, and depositing and growing SiC by a solution growth method. A method for producing an SiC single crystal is also provided.

Description

  The present invention relates to a method for producing a SiC (silicon carbide) single crystal by a solution method, and realizes a significant suppression of void defects due to entrainment of bubbles in the grown crystal by the solution method, and improves the surface morphology. And a high-quality SiC single crystal obtained thereby.

  SiC single crystal with excellent thermal and chemical stability has a band gap energy of about 3 times, a dielectric breakdown electric field of 7 times, and a thermal conductivity of 3 times that of Si (silicon). Addition makes it easy to control the conduction type (p-type and n-type) and allows the formation of a thermal oxide film as well as Si. Application to next-generation power conversion elements having high environmental resistance is strongly expected.

As an SiC single crystal growth method, an Atchison method, a vapor phase method (sublimation method, chemical vapor phase method), or a solution method is known. In the Atchison method, cinnabar sand, which is a Si raw material, and coke, which is a C (carbon) raw material, are arranged around a graphite electrode, and an amorphous plate-like SiC crystal is obtained by energizing and heating the graphite electrode. At this time, impurity control and shape control are difficult and are not suitable for manufacturing a semiconductor substrate. The sublimation method, which is a typical example of the vapor phase method, can produce an inch-size single crystal substrate, but has a problem that the defect density in the crystal is large. The chemical vapor deposition (CVD) method is generally a thin film crystal growth method because it supplies a raw material by gas, and many problems remain as a bulk single crystal growth method.
In the solution method, Si or a Si-containing alloy is melted in a graphite crucible, C is dissolved in the melt from a gas phase by supplying the graphite crucible or a hydrocarbon gas, and a SiC crystal is formed on a single crystal substrate placed in a low temperature part. It is a method of growing a layer by solution deposition. It is known that the solution method is generally advantageous as a method for obtaining a high-quality single crystal because crystal growth is considered to proceed under conditions that are relatively close to a thermal equilibrium state as compared with a gas phase method. For the reasons described above, in recent years, studies have been made on increasing the growth rate and crystal quality of a method for growing a SiC single crystal by a solution method.

Patent Document 1 discloses a SiC seed crystal in a melt containing SiC, which is made of Si and C, or Si, Cr, and M (M: any one of Ti, Fe, Mn, and Co). In a method of growing a SiC single crystal on a seed crystal substrate by immersing the substrate and supersaturating SiC by solution supercooling at least around the seed crystal substrate, a high-quality bulk SiC single crystal that does not contain bubbles, A method of stably producing at a practical growth rate at a temperature of 2000 ° C. or less has been proposed. As an atmospheric gas during single crystal growth, a non-oxidizing gas having a viscosity η of 750 μP or less at the single crystal growth temperature, for example, helium Alternatively, it is described that the generation of bubbles in the grown crystal can be completely suppressed by using a mixed gas containing helium as a main component.
However, in order to perform crystal growth at a high quality with a small amount of impurity elements and at a high growth rate, it is desired to use a binary solution of Si and C and grow at a high temperature of 2000 ° C. or higher. In this case, a method of pressurizing the atmospheric gas is used to prevent evaporation of the Si solution. As a result of an experiment conducted by the inventors, it was not possible to suppress entrainment of bubbles under the crystal growth conditions of a crystal growth temperature of 2100 ° C. and an atmospheric gas (He) of 0.95 MPa.

  Non-Patent Document 1 discloses that crystals are grown at a rate of several tens to 100 μm / h in a binary solution of Si and C under Ar atmosphere gas under crystal growth conditions of crystal growth temperature T ≦ 2300 ° C. and pressure P ≦ 20 MPa. Growth is taking place. However, Non-Patent Document 1 describes that the use of Ar gas to be used or the solution is inevitably involved.

In Patent Document 2, in a method in which a SiC single crystal is grown on a substrate by bringing a SiC single crystal into contact with a solution obtained by melting Si heated in a graphite crucible, Cr and X (X is Ce, Nd) in the melt. At least one of them), and Cr is 30 to 70 at. %, And 1) when X is Ce, Ce is 0.5 to 20 at. %, 2) When X is Nd, Nd is 1 to 25 at. A method of precipitating and growing SiC single crystals with a melt of% is proposed.
However, the technique described in Patent Document 2 has a limited melt composition, and when a melt composition other than this is used, the technique is generally effective for solution growth of SiC single crystals. Is not limited.

In Patent Document 3, in the SiC single crystal precipitation / growth method using the solution method, the ratio (Sc / Ss) of the surface area (Sc) of the SiC seed crystal to the area (Ss) of the solution interface is 0.13 or less. By setting the atmospheric pressure in the crucible before the start of crystal growth to 55 kPa or more and the atmospheric pressure in the crucible after the start of crystal growth to 150 kPa or less, the mixing probability of polycrystals in the SiC single crystal is reduced and the single crystal is A method for producing an SiC single crystal that can reduce the void density of the metal is described.
However, the technique described in Patent Document 3 does not achieve complete suppression of void defects, and the ratio of the surface area (Sc) of the SiC seed crystal to the area (Ss) of the solution interface (Sc / Ss). Therefore, it is necessary to use a crucible having a diameter 7 to 100 times larger than the diameter of the seed crystal used for crystal growth, and it is necessary to increase the size of the apparatus. There is a problem in industrial production. In addition, in order to perform crystal growth at a high quality with a small amount of impurity elements and at a high growth rate, it is desirable to use a binary solution of Si and C and to be at a high temperature of 2000 ° C. or higher. In this case, in the method described in Patent Document 3, the evaporation of the Si solution is remarkable, and it is difficult to carry out at a temperature exceeding 2100 ° C.

JP 2006-69861 A Japanese Patent No. 4450075 JP 2011-68515 A

Material Science Engineering, B61-62, (1999) 29-39.

As described above, the SiC single crystal growth method by the solution method in the above-mentioned known literature is a method using a non-oxidizing gas (for example, He) having an atmospheric gas viscosity of 750 μP or less under conditions of 2000 ° C. or less. Although it describes the effect of reducing macro defects in grown crystals in a specific solution composition, it suppresses voids against all growth temperatures (particularly 2000 ° C. or higher) and solution compositions capable of growing SiC single crystals. It was not an effective way to get. Although a method for realizing void reduction and polycrystal suppression by controlling the pressure of the atmospheric gas and the structure of the crucible / seed crystal is also described, the effect of suppressing the void is not perfect, and the simple manufacturing method is not limited. A large crucible having a diameter 7 to 100 times larger than that of the crystal must be used, and the apparatus must be increased in size, which is problematic in industrial production. In addition, it is desirable to use only Si as a solution for the production of a high-quality, high-purity SiC single crystal. In the methods described in these known documents, when only Si is used as a solution, It is difficult to suppress the macro defects and to improve the growth crystal surface morphology.
The present invention provides a crystal growth temperature at which the SiC solution growth method can be performed regardless of the type of atmospheric gas, the pressure of the atmospheric gas, and whether or not a transition metal element and / or rare earth element is added to a solution containing Si and C. An object of the present invention is to provide a method for growing a SiC single crystal that can significantly suppress void defects typically generated in the solution growth method.

As a result of studying the manufacturing method of the SiC single crystal by the solution method, the present inventors found that the voids in the SiC single crystal were gasified again from the atmospheric gas dissolved in the solution, and the bubbles were crystal-grown. In addition, it was found that it is one of the causes, and in addition, it was found that the solubility of the atmospheric gas in the solution can be controlled by adjusting the solution temperature. Based on these new findings, the method for removing bubbles that cause voids has been further studied, and it has been clarified that the treatment conditions before the seed crystal is immersed in the solution are important, leading to the present invention. .
The object of the present invention has been achieved by the following means.
(1) In immersing a SiC seed crystal in a solution containing Si and C, and precipitating and growing SiC by the solution growth method, the temperature of the solution is temporarily set before immersing the seed crystal in the solution. In particular, the SiC single crystal is manufactured by maintaining the crystal growth temperature at 50 to 300 ° C. higher than the crystal growth temperature, and the void density in the crystal growth portion is set to 10,000 pieces / cm ³ or less.
(2) A method for producing a SiC single crystal by a solution growth method in which a SiC seed crystal is immersed in a solution containing Si and C, and SiC is precipitated and grown, before the seed crystal is immersed in the solution. And a temperature of the solution is temporarily maintained at 50 to 300 ° C. higher than the crystal growth temperature.
(3) The method for producing an SiC single crystal according to (2), wherein the time for keeping the temperature of the solution temporarily higher than the crystal growth temperature is 10 minutes or more and 3 hours or less.
(4) The SiC single crystal is manufactured under a gas atmosphere, and the pressure of the atmosphere gas is set to a pressurizing condition of 0.1 MPa or more. (2) or (3) A method for producing a SiC single crystal.
(5) The method for producing an SiC single crystal according to any one of (2) to (4), wherein the crystal growth temperature is in a range of 1700 to 2100 ° C.
(6) The method for producing a SiC single crystal according to any one of (2) to (5), wherein the solution contains a transition metal element and / or a rare earth element.
(7) A SiC single crystal manufactured by the manufacturing method according to any one of (2) to (6).

  According to the present invention, void defects due to entrainment of atmospheric gas bubbles can be achieved without using a special apparatus even at high temperature at which the solution growth of the SiC single crystal can be carried out and under a pressurized condition where the atmospheric gas pressure is 0.1 MPa or more. A reduced SiC single crystal and a method for producing the same can be provided.

FIG. 1 is a schematic diagram of a SiC single crystal growth experimental apparatus by a solution method used in an example of the present invention. FIG. 2 is a graph showing the time change of the solution temperature in a crystal growth experiment in which the solution was treated at a high temperature before the start of crystal growth in Examples 1 to 3, and the solution was changed from the crystal growth temperature of 1900 ° C. to 200 ° C. before the start of crystal growth. The temperature was kept at 2100 ° C., which was higher. FIG. 3 is a graph showing the change over time of the solution temperature in a crystal growth experiment in which the solution is not treated at a high temperature before the start of crystal growth in Comparative Example 1, and the crystal growth temperature is 1900 ° C. FIG. 4 is a graph showing the change over time of the solution temperature in a crystal growth experiment in which the solution is not treated at a high temperature before the start of crystal growth in Comparative Example 2, and the crystal growth temperature is 2100 ° C. FIG. 5 is an optical micrograph showing a growth surface of the SiC single crystal obtained in Example 1 and a transmission image of a cross section perpendicular to the growth surface. FIG. 6 is an optical micrograph showing a growth surface of the SiC single crystal obtained in Comparative Example 1 and a transmission image of a cross section perpendicular to the growth surface.

  The method for producing a SiC single crystal according to the present invention is a method in which when a SiC single crystal is grown by a solution method, a high temperature treatment of the solution is performed before the seed crystal is immersed in the solution. By using a high temperature of 1700 to 2100 ° C. by maintaining the temperature 50 to 300 ° C. higher than the growth temperature and using a special apparatus even under a pressurized condition where the atmospheric gas pressure is 0.1 MPa or more. In addition, generation of voids in the grown SiC crystal can be suppressed.

  Before immersing the seed crystal in the solution, the temperature of the solution is temporarily kept higher than the growth temperature, thereby making it possible to produce a SiC single crystal in a state in which void generation is suppressed. If the holding temperature is less than the crystal growth temperature + 50 ° C., the effect of suppressing bubble generation is not sufficient, and if the crystal growth temperature exceeds + 300 ° C., the supersaturated concentration of C in the solution becomes too high, and polycrystals are generated Therefore, it is appropriate to temporarily maintain the temperature of the solution at 50 to 300 ° C. higher than the growth temperature. Further, in order to obtain a sufficient suppression effect and prevent the supersaturated concentration of C in the solution from becoming too high, it is more preferable that the high temperature holding time is 10 minutes or more and 3 hours or less.

A description will be given with reference to FIG. 1 showing an example of an embodiment for carrying out the method for producing a SiC single crystal of the present invention.
In the present invention, before immersing the seed crystal in the solution, a high temperature treatment of the solution characterized by temporarily maintaining the temperature of the solution at 50 to 300 ° C. higher than the crystal growth temperature is applied.
The temperature of the high-temperature treatment of the solution performed before immersing the seed crystal in the solution is more preferably 100 to 250 ° C. higher than the crystal growth temperature.
The treatment time of the high temperature treatment of the solution performed before immersing the seed crystal in the solution is not particularly limited as long as the solution temperature reaches 50 to 300 ° C. higher than the crystal growth temperature, but preferably 10 minutes to 3 hours, more preferably 30 minutes to 2 hours.

  In FIG. 1, the growth of the SiC single crystal 2 is performed by using a seed crystal holding shaft (seed crystal holding rod) which is a part of a mechanism for supporting the SiC single crystal substrate 2 in a solution 4 heated by a high-frequency coil 6 serving as a heating device. ) A single crystal substrate 2 made of SiC, which is a seed crystal, is held at the tip of 3 by adhesion or mechanical fixation, and this can be immersed in a solution to grow a single crystal. The seed crystal holding shaft 3 and the graphite crucible 1 are each provided with a mechanism that rotates independently. The temperature of the outer bottom surface of the graphite crucible 1 is directly measured by a high temperature thermometer such as a radiation thermometer. The heating of the graphite crucible 1 by the high-frequency coil 6 is preferably controlled based on the measured temperature on the outer bottom surface of the graphite crucible 1. Here, in FIG. 1, the graphite crucible 1 is covered with a heat insulating material 5, and a high-frequency coil 6 is installed on the outside thereof.

  The shape of the seed crystal may be a plate such as a disk, a hexagonal flat plate, or a rectangular flat plate, or a cube, but a plate shape such as a disc, a hexagonal flat plate, or a square flat plate is preferred. The size of the seed crystal may be any size, and depending on the purpose, the diameter is preferably 0.1 cm or more, more preferably 0.5 cm or more, and even more preferably 1 cm or more. The upper limit of the diameter is not particularly limited, and may be adjusted according to the capacity of the crystal growth apparatus, and may be 10 cm, for example.

In the method for obtaining a SiC single crystal of the present invention, the composition of the solution used for solution growth is not particularly limited as long as at least Si and C are contained. In the present invention, the solution used for solution growth may contain a transition metal element (preferably a first transition element such as Ti or Cr) and / or a rare earth element (for example, scandium or yttrium). In particular, a Si-C solution, a Si-C-Ti solution, or a Si-C-Cr solution is preferable, and the solution contains a transition metal element (preferably a first transition element such as Ti or Cr) or / and a rare earth element. However, before immersing the seed crystal in the solution, by temporarily maintaining the temperature of the solution at 50 to 300 ° C. higher than the growth temperature, voids in the SiC single crystal obtained by crystal growth are greatly increased. It is suppressed. Here, at least a part of C in the Si-C solution, Si-C-Ti solution, and Si-C-Cr solution is dissolved in the solution from the graphite crucible. In addition, there is a method in which a part of C is supplied into the solution by injecting a hydrocarbon gas such as CH ₄ into the solution or by mixing it with an atmospheric gas.

As the atmospheric gas, an inert gas such as He, Ne, or Ar is used to prevent oxidation of the SiC crystal and the solution during the growth of the SiC single crystal, and a gas such as N ₂ , H ₂ , or CH ₄ is mixed. May be. Further, since the SiC crystal growth is performed at a high temperature of 1700 to 2400 ° C., the evaporation of the solution is severe when the atmospheric gas pressure is lower than 0.1 MPa. Therefore, it is desirable to perform the SiC single crystal growth under a pressurized condition. A suitable atmospheric gas pressure is 0.1 MPa or more.

The temperature at the time of SiC single crystal growth by the production method of the present invention can be set within a range of 1700 to 2100 ° C., but an optimum temperature condition can be arbitrarily set within a range of 1700 to 2100 ° C. depending on the solution composition. That's fine. However, since the evaporation of the solution becomes severe depending on the temperature when crystal growth or the solution is kept at a high temperature, the pressure of the atmospheric gas is higher than 0.1 MPa to 1 MPa and 1900 ° C. at a solution temperature of 1700 to 1900 ° C. A solution temperature in the range of 2400 ° C. or lower is preferably 1 MPa to 10 MPa.
By the SiC single crystal growth by the solution method in the present invention, generation of voids in the SiC single crystal obtained by growing at a high temperature for a long time, for example, 3 hours or more can be significantly suppressed.
That is, in immersing a SiC seed crystal in a solution containing Si and C, and precipitating and growing SiC, the SiC seed crystal is immersed in a solution containing Si and C, and SiC is precipitated and grown. In this case, before immersing the seed crystal in the solution, the SiC single crystal obtained by temporarily maintaining the temperature of the solution at 50 to 300 ° C. higher than the crystal growth temperature has a void density of 10,000 pieces. / Cm ³ or less. The void density is preferably 1000 / cm ³ or less, more preferably 100 / cm ³ or less. Thereby, generation | occurrence | production of the void of diameter 1 micrometer or more which is a problem by generation | occurrence | production of a void can be suppressed significantly, and it can also be substantially 0 piece / cm < ³ >.

The void density can be measured as follows.
That is, using an optical microscope, the number of voids is measured in a region including all of the crystal growth portion in the thickness direction by transmission illumination. Here, since the void is observed as a black dot by transmitted illumination, it can be easily measured. In addition, the spatial resolution of observation with an optical microscope is about 1 μm, and a void having a size of 1 μm or more in question can be sufficiently detected. More specifically, in a 2 mm × 2 mm region on the plane of the crystal growth portion, the total thickness of the crystal growth portion (for example, 100 μm if the crystal growth thickness is 100 μm) is observed with a microscope and the number of voids Measurement is performed, and the measurement is repeated a total of 6 times at an arbitrary place, and the average value is obtained by converting per 1 cm ³ . The following examples and comparative examples were obtained in this way. Here, when the thickness cannot be observed with the transmitted illumination, the thickness can be measured by dividing in the thickness direction and repeating the measurement.

Examples are given below for the purpose of specifically explaining the present invention. However, these examples are for the purpose of illustrating the present invention and are not intended to limit the present invention.
In the following examples, a SiC single crystal was grown using the same apparatus as that of the SiC single crystal growth embodiment shown in FIG. In the experiment, Si was used as the solution, the crystal growth temperature was 1900 ° C., and the atmospheric gas pressure was 0.95 MPa. Before immersing the seed crystal in the solution, as a high temperature treatment, the temperature of the solution was maintained at 200 ° C. higher than the crystal growth temperature for 1 hour. The seed crystal used here was a plate-like SiC single crystal substrate having a size of 2.5 to 5.1 cm.

  In the experiment, the graphite crucible was filled with Si, held at a temperature below the melting point of Si under reduced pressure, and the adsorbed gas was degassed, and then filled with Ar gas at a pressure of 0.95 MPa as the atmospheric gas, The Si raw material was melted by heating so that the bottom surface had a predetermined temperature. Thereafter, the temperature of the solution was maintained for 1 hour in a state of 200 ° C. higher than the growth temperature, and then the temperature was lowered to the crystal growth temperature. Thereafter, the SiC seed crystal held by the same structure as the seed crystal holding shaft illustrated in FIG. 1 is immersed in the solution, and after the immersion time of 3 hours has elapsed, the seed crystal holding shaft is raised, Pulled from. During crystal growth, the seed crystal holding shaft and the graphite crucible were rotated in opposite directions.

  After the temperature in the furnace was cooled to room temperature, the SiC seed crystal was recovered and washed with hydrofluoric acid to remove the solidified product of the solution adhering to the SiC crystal surface. The surface and cross section of the SiC single crystal grown by the solution method on the seed crystal was observed with a microscope using transmitted illumination, and the void density in the grown crystal was measured as described above.

Example 1
In the experiment, the graphite crucible was filled with Si, the graphite crucible and the Si raw material were kept at a temperature of about 1100 ° C. under a reduced pressure of 1 Pa or less, the adsorbed gas was degassed, and Ar gas was 0.95 MPa as the atmospheric gas. Filled to a pressure and heated so that the bottom surface of the graphite crucible was 1900 ° C. to melt the Si raw material. Thereafter, the temperature of the solution was maintained for 1 hour in a state of 200 ° C. higher than the growth temperature, and then the temperature was lowered to the crystal growth temperature. Thereafter, the SiC seed crystal held by the same structure as the seed crystal holding shaft illustrated in FIG. 1 is immersed in the solution, and after the immersion time of 3 hours has elapsed, the seed crystal holding shaft is raised, Pulled from. The time change of the solution temperature during the high temperature treatment and crystal growth of the solution carried out in Example 1 is shown in FIG. During crystal growth, the seed crystal holding shaft and the graphite crucible were rotated in opposite directions.

(Comparative Example 1)
After filling the graphite crucible with Si, holding the graphite crucible and the Si raw material at a temperature of about 1100 ° C. under a reduced pressure of 1 Pa or less, degassing the adsorbed gas, and then setting the Ar gas to a pressure of 0.95 MPa as the atmospheric gas Then, the Si crucible was heated so that the bottom surface of the graphite crucible became 1900 ° C. to melt the Si raw material. Thereafter, the SiC seed crystal held by the same structure as the seed crystal holding shaft illustrated in FIG. 1 is immersed in the solution, and after the immersion time of 3 hours has elapsed, the seed crystal holding shaft is raised, Pulled from. During crystal growth, the seed crystal holding shaft and the graphite crucible were rotated in opposite directions. The time change of the solution temperature during the crystal growth performed in Comparative Example 1 is shown in FIG.

(Comparative Example 2)
After filling the graphite crucible with Si, holding the graphite crucible and the Si raw material at a temperature of about 1100 ° C. under a reduced pressure of 1 Pa or less, degassing the adsorbed gas, and then setting the Ar gas to a pressure of 0.95 MPa as the atmospheric gas And heated so that the bottom surface of the graphite crucible was 2100 ° C., and the Si raw material was melted. Thereafter, an SiC seed crystal held by the same structure as the seed crystal holding shaft illustrated in FIG. 1 is immersed in the solution, and after the immersion time of 1 hour has elapsed, the seed crystal holding shaft is raised, Pulled from. During crystal growth, the seed crystal holding shaft and the graphite crucible were rotated in opposite directions. The time change of the solution temperature during the crystal growth performed in Comparative Example 2 is shown in FIG.

  The optical microscope photograph which shows the transmission image of the cross section perpendicular | vertical to a growth surface and a growth surface of the SiC crystal grown by the method of Example 1 was shown in FIG. According to FIG. 5, void generation can be suppressed in the SiC single crystal growth by the method described in the first embodiment. In this method, during the high temperature treatment of the solution, the dissolved amount of atmospheric gas in the solution is lower than the dissolved amount in the thermodynamic equilibrium state at the crystal growth temperature. Even if the solution temperature is lowered, the fact that the amount of dissolved atmospheric gas in the solution is lower than the amount dissolved in the thermodynamic equilibrium state at the crystal growth temperature is considered to be one of the factors for suppressing the void.

  An optical micrograph showing a transmission image of the SiC crystal grown by the method of Comparative Example 1 and a cross section perpendicular to the growth surface is shown in FIG. According to FIG. 6, when the high temperature treatment of the solution before crystal growth is not performed, voids in the SiC single crystal cannot be suppressed. Note that the black dots in FIG. 6 are voids.

  The void density in the SiC single crystal produced by Example 1, Comparative Example 1 and Comparative Example 2 is shown in Table 1 below.

  As apparent from Table 1 and FIG. 6, in the crystal growth conditions described in Example 1, when the high-temperature treatment of the solution before crystal growth is not performed, voids are generated in the grown SiC single crystal. It cannot be suppressed.

  As is apparent from Table 1, void generation is not generated in the SiC single crystal growth using the crystal growth conditions described in Comparative Example 2 in which the growth temperature is simply increased by 200 ° C. compared to the crystal growth conditions described in Comparative Example 1. Although slightly reduced, there is no effect of greatly suppressing the generation of voids.

(Example 2)
A SiC single crystal was produced in the same manner as in Example 1 except that the solution raw material was changed to Si _0.77 Ti _0.23 and changed to a Si—C—Ti solution.

(Example 3)
A SiC single crystal was produced in the same manner as in Example 1 except that the solution raw material was changed to Si _0.6 Cr _0.4 and changed to a Si—C—Cr solution.

  Also in Example 2 and Example 3, it was possible to significantly suppress the generation of voids.

  According to the method for producing a SiC single crystal of the present invention, even when the crystal growth temperature is high and the atmospheric gas pressure is 0.1 MPa or more, the generation of voids is greatly suppressed, and high quality without containing voids. It becomes possible to produce a SiC single crystal.

1 graphite crucible 2 SiC seed crystal 3 seed crystal holding shaft 4 solution 5 heat insulating material 6 high frequency coil

Claims (7)

In immersing SiC seed crystals in a solution containing Si and C, and precipitating and growing SiC by the solution growth method, the temperature of the solution is temporarily crystallized before immersing the seed crystals in the solution. A SiC single crystal produced by maintaining a temperature higher by 50 to 300 ° C. than the growth temperature, and having a void density in the crystal growth portion of 10,000 pieces / cm ³ or less.   A method for producing a SiC single crystal by a solution growth method in which a SiC seed crystal is immersed in a solution containing Si and C, and SiC is precipitated and grown, and before the seed crystal is immersed in the solution, A method for producing a SiC single crystal, characterized in that the temperature of the solution is temporarily maintained at a temperature higher by 50 to 300 ° C than the crystal growth temperature.   3. The method for producing an SiC single crystal according to claim 2, wherein the time during which the temperature of the solution is temporarily kept higher than the crystal growth temperature is 10 minutes or longer and 3 hours or shorter.   The production of the SiC single crystal according to claim 2 or 3, wherein the production of the SiC single crystal is performed in a gas atmosphere, and the pressure of the atmospheric gas is set to a pressure condition of 0.1 MPa or more. Method.   The said crystal growth temperature exists in the range of 1700-2100 degreeC, The manufacturing method of the SiC single crystal of any one of Claims 2-4 characterized by the above-mentioned.   The method for producing a SiC single crystal according to any one of claims 2 to 5, wherein the solution contains a transition metal element and / or a rare earth element.   The SiC single crystal manufactured with the manufacturing method of any one of Claims 2-6.