JP5304600B2 - SiC single crystal manufacturing apparatus and manufacturing method - Google Patents

Description

  The present invention relates to an apparatus and a method for producing a SiC single crystal by a so-called solution method.

  SiC is a semiconductor having excellent physical properties such as a band gap of about 3 times that of Si and a breakdown electric field strength of about 10 times that of Si. If this can be applied to a power device, the power consumption is lower than that of a Si power device. A lossy device can be realized. In addition, the SiC power device not only has a small power loss compared to the Si power device, but can operate at a higher temperature and a higher speed. Therefore, high efficiency and miniaturization can be achieved in a power converter such as an inverter by using a SiC power device.

  Conventionally, a sublimation method or a solution method is known as a method for producing such a SiC single crystal.

  In the solution method, the seed crystal is immersed in the melt in which the raw material is dissolved, and, for example, a temperature gradient is provided so that the temperature decreases from the inside of the melt toward the melt surface. This is a method in which a dissolved raw material is supersaturated and deposited on a seed crystal. In the production of a SiC single crystal by a solution method, it has been reported that micropipes present in a seed crystal disappear during the growth process. On the other hand, in the production of a SiC single crystal by a solution method, a crucible made of graphite is generally used, and carbon (C), which is the other raw material of the SiC single crystal, is supplied from this graphite crucible into the Si melt. The However, since the amount of carbon dissolved in the Si melt from the graphite crucible is very small, the production of SiC single crystal by the solution method has a problem that the growth rate in crystal growth is slow. For this reason, a technique has been conventionally proposed in which elements such as Ti, Mn, and Cr are added to a melt in which raw materials are dissolved to increase the carbon concentration in the melt, thereby improving the growth rate of the SiC single crystal. (For example, refer to Patent Documents 1 to 5).

  However, since the carbon that is the raw material of the SiC single crystal is supplied from the graphite crucible as described above, if the carbon concentration in the melt is increased by adding elements such as Ti, Mn, Cr, etc., naturally the graphite crucible The carbon concentration in the melt near the wall is the highest. On the other hand, since the melt surface is also an interface with the atmospheric gas, the temperature gradient is most likely to be near the melt surface. Therefore, on the surface of the melt near the graphite crucible wall, the carbon concentration tends to be supersaturated, so that SiC coarse crystals (hereinafter referred to as polycrystals) tend to precipitate. When such a polycrystal adheres to the surface of the growing seed crystal, for example, there is a possibility that the single crystal growth from the seed crystal which is the original purpose is hindered. Therefore, such polycrystalline precipitation is a serious problem in single crystal growth by the solution method.

  In Patent Document 6, the inside of a crucible installed in a chamber is divided into an inner part and an outer part by a cylindrical partition, and the granular raw material is continuously added to the melt of the single crystal raw material in the outer part of the crucible. A device for growing a single crystal while supplying it, and extending a cylinder that concentrically surrounds the single crystal being grown from the upper part of the chamber and shrinking it downward at the lower end of the cylinder. In a single crystal pulling apparatus configured by attaching a heat insulating ring in the shape of a truncated cone having a diameter, the outer shell of the heat insulating ring is made of a carbon material, and the heat insulating material is filled in the outer shell. A single crystal pulling apparatus is described. Further, in Patent Document 6, according to such a single crystal pulling apparatus, the vicinity of the interface between the partition walls and the melt surface can be maintained at a high temperature, so that solidification of the melt in the vicinity of the partition walls can be prevented, It describes that productivity can be improved by increasing the growth rate of single crystals.

JP 2004-2173 A JP 2007-76986 A JP 2007-261843 A JP 2007-261844 A JP 2000-264790 A Japanese Unexamined Patent Publication No. 7-69779

  In the single crystal pulling apparatus described in Patent Document 6, the lower end of the heat insulating ring is disposed at a position 10 mm or more away from the melt surface. Therefore, when an SiC single crystal is manufactured using such an apparatus, the precipitation of polycrystals in the vicinity of the inner wall of a graphite crucible used as a crucible in the manufacture of an SiC single crystal cannot be sufficiently prevented.

  Therefore, an object of the present invention is to provide a SiC single crystal manufacturing apparatus and a manufacturing method capable of suppressing the precipitation of the polycrystal as described above when the SiC single crystal is manufactured by a solution method.

The present invention for solving the above problems is as follows.
(1) A graphite crucible for containing a raw material melt as a raw material for SiC single crystal, a heating means arranged around the graphite crucible, and arranged to be movable in the vertical direction above the graphite crucible. A SiC single crystal production comprising: a seed crystal holding part; and a seed crystal held at a lower end of the seed crystal holding part is immersed in a raw material melt in the graphite crucible to grow a SiC single crystal under the seed crystal In the apparatus, a heat insulating material is disposed on the inner wall of the graphite crucible so as not to contact at least a part of a portion where the inner wall of the graphite crucible and the liquid surface of the raw material melt contact. SiC single crystal production equipment.
(2) The heat insulating material is disposed on the entire circumference of the inner wall of the graphite crucible so that the inner wall of the graphite crucible does not contact the liquid surface of the raw material melt. SiC single crystal manufacturing equipment.
(3) The SiC single crystal manufacturing apparatus according to (1) or (2), wherein the heat insulating material has an annular shape.
(4) The SiC single crystal manufacturing apparatus according to any one of (1) to (3), wherein the heat insulating material includes carbon fiber.
(5) The SiC single crystal manufacturing apparatus according to any one of (1) to (3), wherein the heat insulating material is made of carbon felt.
(6) A graphite crucible for containing a raw material melt as a raw material for SiC single crystal, a heating means arranged around the graphite crucible, and arranged to be movable in the vertical direction above the graphite crucible. A seed crystal holding portion, and at least part of the portion where the inner wall of the graphite crucible and the liquid surface of the raw material melt are in contact with each other, a heat insulating material is disposed on the inner wall of the graphite crucible so as not to contact A SiC single crystal is grown under a seed crystal by immersing the seed crystal held at the lower end of the seed crystal holding unit in a raw material melt in the graphite crucible using an SiC single crystal manufacturing apparatus. A method for producing a SiC single crystal.
(7) The heat insulating material is arranged on the entire circumference of the inner wall of the graphite crucible so that the inner wall of the graphite crucible does not contact the liquid surface of the raw material melt. Method.
(8) The method according to (6) or (7) above, wherein the heat insulating material has an annular shape.
(9) The method according to any one of (6) to (8), wherein the heat insulating material includes carbon fiber.
(10) The method according to any one of (6) to (8) above, wherein the heat insulating material is made of carbon felt.

  According to the SiC single crystal manufacturing apparatus and manufacturing method of the present invention, it is possible to significantly suppress the precipitation of polycrystals on the melt surface, particularly on the melt surface near the crucible wall. Therefore, according to the SiC single crystal manufacturing apparatus and manufacturing method of the present invention, it is possible to prevent such a polycrystalline body from gradually expanding from the crucible wall and covering the entire melt surface. It is possible to stably grow the SiC single crystal for a long time without hindering the single crystal growth.

It is sectional drawing which showed typically an example of the SiC single crystal manufacturing apparatus by this invention. (A) is the photograph which shows the melt surface after heat-maintaining a raw material melt for 5 hours at the temperature of 1900-1935 degreeC without a heat insulating material, (b) is a raw material melt similarly without a heat insulating material. Is a photograph showing the surface of the melt after being heated and held at a temperature of 1900-1935 ° C. for 10 hours. It is an example of the heat insulating material which consists of a graphite crucible and a carbon felt used in the SiC single crystal manufacturing apparatus of this invention. (A) is the photograph which shows the melt surface after heat-maintaining the raw material melt for 5 hours at the temperature of 1900-1935 degreeC using the heat insulating material which consists of annular carbon felt, (b) is a circle. It is a photograph which shows the melt surface after heat-maintaining a raw material melt for 5 hours at the temperature of 1900-1935 degreeC using the heat insulating material which lacked one part of heat insulating material consisting of cyclic carbon felt. It is a schematic cross section near the graphite crucible wall showing the effect of the heat insulating material in the present invention.

  The SiC single crystal production apparatus of the present invention includes a graphite crucible for containing a raw material melt as a raw material for SiC single crystal, a heating means disposed around the graphite crucible, and a vertical direction above the graphite crucible. And a seed crystal holding part movably arranged on the bottom of the seed crystal holding part, and immersing the seed crystal held at the lower end of the seed crystal holding part in the raw material melt in the graphite crucible, In the SiC single crystal manufacturing apparatus for growing the material, a heat insulating material is disposed on the inner wall of the graphite crucible so that they do not contact at least a part of a portion where the inner wall of the graphite crucible and the liquid surface of the raw material melt contact each other. It is characterized by that.

  As described above, in the production of an SiC single crystal by the solution method, a crucible made of graphite is generally used, and carbon (C), which is another raw material of the SiC single crystal, is introduced into the Si melt from the graphite crucible. ) Is supplied. On the other hand, since the melt surface is also an interface with the atmospheric gas, the temperature gradient is most likely to be near the melt surface. Therefore, on the surface of the melt near the graphite crucible wall, the carbon concentration becomes supersaturated, and SiC coarse crystals, that is, polycrystals tend to precipitate. Such a phenomenon becomes particularly prominent when elements such as Ti, Mn, and Cr are added in order to improve the carbon concentration in the melt in which the raw material is dissolved. Further, in the production of the SiC single crystal by the solution method, for example, in order to move the carbon dissolved in the raw material melt from the graphite crucible toward the seed crystal, a seed crucible and / or a seed crystal holding unit that holds the seed crystal. Is rotating. Therefore, the polycrystals deposited on the inner wall of the graphite crucible as described above gradually expand to the center of the melt surface, and eventually cover the entire melt surface. In such a state, of course, it becomes impossible to grow a SiC single crystal on the seed crystal, but even at the stage where the entire melt surface is covered with such a polycrystal, for example, If the deposited polycrystal adheres to the surface of the growing seed crystal, the single crystal growth from the seed crystal which is the original purpose is hindered.

  The present inventors preferably arrange a heat insulating material on the inner wall of the graphite crucible so that they do not contact at least a part of the portion where the inner wall of the graphite crucible and the liquid surface of the raw material melt contact, By arranging a heat insulating material on the entire circumference of the inner wall of the graphite crucible so that the inner wall of the crucible and the liquid surface of the raw material melt do not come into contact with each other, SiC polycrystal is deposited on the melt surface near the inner wall of the graphite crucible. It was found that it can be remarkably suppressed. Furthermore, the present inventors have found that the state of the melt central portion for growing a SiC single crystal can always be maintained in a good state by suppressing the precipitation of polycrystals in the vicinity of the inner wall of the graphite crucible.

  FIG. 1 is a cross-sectional view schematically showing an example of a SiC single crystal manufacturing apparatus according to the present invention.

  Referring to FIG. 1, an SiC single crystal manufacturing apparatus 10 includes a graphite crucible 2 for containing a raw material melt 1 that is a raw material of an SiC single crystal, a heating means 3 disposed around the graphite crucible 2, The graphite crucible 2 is arranged so as to be movable in the vertical direction above the graphite crucible 2, and includes a seed crystal holding part 5 holding the seed crystal 4 at the lower end, an optional lid part 7 for the graphite crucible 2, and the lid part 7 And an optional heat insulating material 8 disposed on both sides of the graphite crucible, and the graphite crucible 2 and the liquid surface of the raw material melt 1 are in contact with at least a part of a portion where the graphite wall does not contact the graphite. A heat insulating material 6 is disposed on the inner wall of the crucible 2. More specifically, the graphite crucible 2 is composed of an inner portion 2a and a susceptor portion 2b that holds the inner portion 2a. Further, in the production of the SiC single crystal using the SiC single crystal production apparatus 10, the graphite crucible 2, the heating means 3, etc. are provided in the chamber 9 in order to prevent a chemical reaction between the produced SiC single crystal and the atmospheric gas. The chamber 9 is filled with an inert gas such as argon.

  When an SiC single crystal is manufactured using the SiC single crystal manufacturing apparatus 10 according to the present invention, for example, first, a melt raw material is introduced into the graphite crucible 2 and the chamber 9 is evacuated. The inside of the chamber 9 is pressurized to atmospheric pressure or a pressure higher than that by the active gas. Next, the graphite crucible 2 is heated by the heating means 3 to melt the melt raw material to form the raw material melt 1. Next, the seed crystal holding unit 5 is lowered from above with respect to the melted raw material melt 1 to bring the seed crystal into contact with the liquid surface of the raw material melt 1. A SiC single crystal is formed under the seed crystal by pulling up while slowly rotating.

  According to the SiC single crystal manufacturing apparatus 10 of the present invention, heat radiation from the melt surface near the inner wall of the graphite crucible 2 can be suppressed by the heat insulating material 6 disposed on the inner wall of the graphite crucible 2. Therefore, a rapid temperature drop in this portion can be suppressed, that is, the carbon dissolved in the melt in this portion can be suppressed from being supersaturated, so that it is formed on the inner wall of the graphite crucible 2. Precipitation as a polycrystal can be prevented.

  According to the present invention, as the heat insulating material disposed on the inner wall of the graphite crucible, a material that is generally excellent in heat resistance and hardly reacts with the raw material melt can be selected. For example, a metal having high heat resistance such as tantalum may be used as the material for the heat insulating material. However, such a metal is very expensive, and when it is dissolved in the raw material melt, it is mixed as an impurity. Therefore, as the heat insulating material disposed on the inner wall of the graphite crucible, a carbon-based material is preferably used, more preferably a material containing carbon fiber is used, and most preferably a carbon felt made of carbon fiber is used. . These materials are inexpensive and excellent in heat resistance, and even when eroded and dissolved by a high-temperature raw material melt, they can be used as a carbon source for a SiC single crystal. Therefore, by using a carbon-based material as the heat insulating material, the carbon concentration in the raw material melt increases, so that the growth rate of the SiC single crystal can be improved.

  Further, the heat insulating material disposed on the inner wall of the graphite crucible is such that the inner wall of the graphite crucible and the liquid surface of the raw material melt do not contact each other, in other words, the liquid surface of the raw material melt falls within the range of the thickness of the heat insulating material. Installed to be inside. In the present invention, the “liquid surface of the raw material melt” refers to an interface between the raw material melt and an atmosphere gas, for example, an inert gas such as argon. According to the present invention, by attaching a heat insulating material to such a position, heat radiation from the melt surface in the vicinity of the inner wall of the graphite crucible can be reliably suppressed. Therefore, as described above, the carbon dissolved in the melt of this portion can be prevented from being supersaturated, and thus it is prevented from being precipitated as a polycrystal on the inner wall of the graphite crucible. be able to. On the other hand, when the heat insulating material is attached at a position higher than the liquid surface of the raw material melt, or is attached in a state of being completely immersed in the raw material melt, the melt surface near the inner wall of the graphite crucible Since the heat radiation from can not be reliably suppressed, the above effect cannot be obtained sufficiently.

  According to the present invention, as the heat insulating material disposed on the inner wall of the graphite crucible, one having an arbitrary shape that can at least partially prevent contact between the inner wall of the graphite crucible and the liquid surface of the raw material melt is used. be able to. However, in order to reliably suppress the precipitation of polycrystals in the vicinity of the inner wall of the graphite crucible, it is preferable to arrange a heat insulating material around the inner wall of the graphite crucible. As such a heat insulating material, for example, a graphite crucible It is preferable to use an annular one having an outer diameter corresponding to the inner diameter of the ring. The inner diameter of the annular heat insulating material is not particularly limited as long as the free surface of the raw material melt sufficient to grow a SiC single crystal on the seed crystal is obtained.

  The heat insulating material can be attached to the inner wall of the graphite crucible by an arbitrary method. For example, the heat insulating material may be installed on the inner wall of the graphite crucible using an adhesive, or may be installed in such a manner that a flange portion is provided on the inner wall of the graphite crucible and the heat insulating material is placed thereon. Various methods of installing or fixing the heat insulating material are conceivable, but there is no significant difference in the effect as long as the surface of the raw material melt is attached so as to be within the thickness range of the heat insulating material.

  Moreover, the thickness of the heat insulating material disposed on the inner wall of the graphite crucible is not particularly limited, but is generally 5 to 20 mm, particularly preferably about 10 to 20 mm. For example, when carbon-based materials, particularly carbon felt, are used as heat insulating materials, they are eroded by a certain amount per unit time by a high-temperature raw material melt, so when they are completely eroded, It is no longer possible to fully exhibit the effect of suppressing the precipitation of polycrystals. Therefore, the thickness of the heat insulating material is determined by considering the temperature and time when manufacturing the SiC single crystal, the size of the graphite crucible, etc., for example, during the operation of manufacturing the SiC single crystal, What is necessary is just to determine suitably in the range which does not melt | dissolve completely in.

  According to the present invention, as the heating means disposed around the graphite crucible, any heating means known to those skilled in the art capable of temperature control can be used. For example, resistance heating, high frequency induction heating, or the like can be used as such a heating means.

  According to the present invention, as the seed crystal holding portion disposed so as to be movable in the vertical direction above the graphite crucible, a material that is generally excellent in heat resistance and hardly reacts with the raw material melt can be selected. Preferably, a material made of graphite can be used. In the present invention, it is also preferable to use a material made of graphite for a member such as a lid that is optionally disposed on the upper portion of the graphite crucible.

  In the production of an SiC single crystal using the SiC single crystal production apparatus according to the present invention, the graphite crucible and the seed crystal holding unit move, for example, carbon dissolved in the raw material melt from the graphite crucible toward the seed crystal. Optionally, either one or both can be rotated. The rotation at this time may be steady rotation or acceleration / deceleration rotation. Further, the rotation directions of the graphite crucible and the seed crystal holding part may be the same direction or the opposite directions. These rotation speeds, rotation directions, and the like may be appropriately determined according to the operating conditions of the SiC single crystal manufacturing apparatus.

  Moreover, the temperature of the raw material melt at the time of manufacturing the SiC single crystal may be a temperature equal to or higher than the melting point of the raw material in order to maintain the dissolved state of the raw material, for example, a temperature of 1800 ° C. or higher. . If the temperature of the raw material melt exceeds 2300 ° C., problems such as Si evaporating vigorously from the raw material melt occur. Therefore, the temperature of the raw material melt is generally preferably 2300 ° C. or lower. In order to ensure stable crystal growth, the temperature of the raw material melt decreases from the inside toward the surface in contact with the seed crystal, for example, with a temperature gradient of 10 to 45 ° C./cm. It is preferable to control the temperature.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to these Examples at all.

  In this example, the effect of attaching a heat insulating material on the inner wall of a graphite crucible was examined using the SiC single crystal production apparatus of the present invention shown in FIG.

[Comparative Example 1]
As Comparative Example 1, a SiC single crystal produced by a solution method was used by using the same SiC single crystal production apparatus as the SiC single crystal production apparatus of the present invention shown in FIG. 1 except that the heat insulating material was not attached to the inner wall of the graphite crucible. And the precipitation state of SiC polycrystal on the surface of the raw material melt at that time was examined. The seed crystal holding unit of the SiC single crystal manufacturing apparatus is provided with a thermocouple inside (at a position 2 mm from the seed crystal), and outputs to the heating means based on the temperature measured by the thermocouple. By adjusting, the surface temperature of the raw material melt was maintained in the range of 1900 to 1935 ° C. The results are shown in FIGS. 2 (a) and 2 (b).

  FIG. 2 (a) is a photograph showing the melt surface after producing a SiC single crystal by a solution method while heating and holding the raw material melt at a temperature of 1900 to 1935 ° C. for 5 hours. In FIG. 2 (a), the portion that appears white in the outer ring shape is SiC polycrystal, and the ring-like portion that appears white on the inner side is simply a solidified raw material melt due to the temperature drop after the experiment.

  FIG. 2B is a photograph showing the surface of the melt after the SiC single crystal is produced by the solution method while the raw material melt is similarly heated and held at a temperature of 1900 to 1935 ° C. for 10 hours. As is clear from FIG. 2B, it can be seen that when the raw material melt is heated and held at a temperature of 1900 to 1935 ° C. for 10 hours, almost the entire melt surface is covered with polycrystals. From the results of FIGS. 2 (a) and 2 (b), it can be seen that the precipitation of such polycrystals expands from the inner wall surface of the graphite crucible toward the center of the melt surface over time. Recognize.

[Example 1]
FIG. 3 shows an example of a heat insulating material made of graphite crucible and carbon felt. In this example, the SiC single crystal manufacturing apparatus of the present invention shown in FIG. 1 in which a heat insulating material made of an annular carbon felt as shown in this figure was arranged on the inner wall of a graphite crucible was used.

[Adhesion of carbon felt to graphite crucible]
A heat insulating material made of an annular carbon felt having an outer shape corresponding to the inner diameter of the graphite crucible was attached to the entire circumference of the inner wall of the graphite crucible according to the following procedure using the adhesive shown in Table 1 below.

  First, an adhesive having the composition shown in Table 1 was applied to the adhesion surfaces of the graphite crucible and the carbon felt, and then bonded together, while applying a load of about 0.5 to 2.0 kgf on the adhesion surface. Primary degreasing and solidification were performed by heating to about 200 ° C. Next, using a heating atmosphere furnace (degreasing furnace and firing furnace), heating is performed at 200 ° C. for 1 hour and further at 700 ° C. for 3 hours while applying a load of about 0.5 to 2.0 kgf to the bonding surface as before. The adhesive was heat-cured by holding, and then furnace-cooled to room temperature.

  A SiC single crystal was manufactured using the above SiC single crystal manufacturing apparatus, and the precipitation state of the SiC polycrystal on the raw material melt surface at that time was examined. As in the case of Comparative Example 1, the surface temperature of the raw material melt was set to 1900 by a thermocouple installed inside the seed crystal holding part (position 2 mm from the seed crystal) and heating means arranged around the graphite crucible. The temperature was controlled in the range of ˜1935 ° C. and held for 5 hours. The result is shown in FIG.

  FIG. 4 (a) is a photograph showing the melt surface after producing a SiC single crystal by a solution method while keeping the raw material melt heated at a temperature of 1900 to 1935 ° C. for 5 hours. Referring to FIG. 4 (a), when the SiC single crystal manufacturing apparatus of the present invention is used, it is compared with FIG. 2 (a) of Comparative Example 1 in which a similar experiment was performed without a heat insulating material made of carbon felt. This clearly shows that no SiC polycrystal is precipitated.

[Example 2]
In this example, as shown in a schematic diagram above FIG. 4B, an experiment similar to that in Example 1 was performed using a heat insulating material lacking a part of the heat insulating material made of an annular carbon felt. went. The result is shown in FIG.

  FIG. 4B is a photograph showing the melt surface after the SiC single crystal is produced by the solution method while the raw material melt is heated and held at a temperature of 1900 to 1935 ° C. for 5 hours. Referring to FIG. 4 (b), it can be seen that polycrystal precipitation is observed in the portion lacking the carbon felt, but polycrystal is not precipitated in the portion where the carbon felt exists. Further, in both cases of FIGS. 4 (a) and 4 (b), no polycrystalline precipitate was observed in the heat insulating material made of carbon felt itself. From these results, it was found that the precipitation of polycrystals can be remarkably suppressed by attaching a heat insulating material made of carbon felt on the inner wall of the graphite crucible in contact with the raw material melt.

  The results of Examples 1 and 2 and Comparative Example 1 are summarized as follows.

  In the operation of manufacturing the SiC single crystal by the solution method, SiC is precipitated as a polycrystal from the surface of the raw material melt 11 near the inner wall of the graphite crucible 12 as shown in FIG. Such a polycrystalline body gradually expands to the center of the melt surface with the passage of time, and eventually covers the entire melt surface. However, according to the SiC single crystal manufacturing apparatus of the present invention, as shown in FIG. 5B, the heat insulating material 13 made of carbon felt is a portion where the inner wall of the graphite crucible 12 and the liquid surface of the raw material melt 11 are in contact with each other. By disposing them so that they do not come into contact with at least a part of them, it is possible to remarkably suppress the precipitation of polycrystals on the surface of the melt near the graphite crucible wall 12. In particular, by disposing the heat insulating material 13 around the entire inner wall of the graphite crucible 12, it is possible to reliably suppress the precipitation of polycrystals. Therefore, since such a polycrystalline body does not gradually expand from the graphite crucible wall and cover the entire melt surface, the state of the melt central portion where the SiC single crystal grows is always maintained in a good state. be able to.

[Example 3]
In this example, with respect to the SiC single crystal manufacturing apparatus of the present invention shown in FIG. 1, as shown in Table 2 below, experiments were performed using annular carbon felts (outer diameter 100 mm, inner diameter 80 mm) having various thicknesses. The condition of the carbon felt and the melt surface when the raw material melt was heated and held at a temperature of 1900 to 1950 ° C. was examined.

  The circles in the figure indicate the case where carbon felt remains in a form that can be clearly confirmed after the experiment. In addition, △ marks indicate that it was difficult to confirm carbon felt, but no precipitation of polycrystals was observed, and X marks indicate that the carbon felt was completely damaged due to erosion by the high-temperature raw material melt. This shows a case where polycrystalline precipitates are observed on the inner wall surface of the graphite crucible.

  In all the experiments in Table 2, no polycrystal was deposited in the melt center. That is, by attaching a heat insulating material made of carbon felt on the inner wall surface of the graphite crucible so that the surface of the raw material melt exists within the thickness range, the surface of the melt, in particular, the actual SiC single crystal It was possible to always maintain the state of the center of the melt in which the crystal grows in a state where crystal growth is possible.

DESCRIPTION OF SYMBOLS 1 Raw material melt 2 Graphite crucible 3 Heating means 4 Seed crystal 5 Seed crystal holding part 6 Heat insulating material 7 Cover part 8 Heat insulating material 9 Chamber 10 SiC single crystal manufacturing apparatus

Claims (10)

  A graphite crucible for containing a raw material melt serving as a raw material for SiC single crystal, a heating means arranged around the graphite crucible, and a seed crystal holding arranged so as to be vertically movable above the graphite crucible A SiC single crystal production apparatus for growing a SiC single crystal under a seed crystal by immersing the seed crystal held at the lower end of the seed crystal holding part in a raw material melt in the graphite crucible, A heat-insulating material is disposed on the inner wall of the graphite crucible so as not to contact at least a part of a portion where the inner wall of the graphite crucible and the liquid surface of the raw material melt are in contact with each other. Crystal manufacturing equipment.   2. The SiC single crystal production according to claim 1, wherein the heat insulating material is disposed on the entire circumference of the inner wall of the graphite crucible so that the inner wall of the graphite crucible does not contact the liquid surface of the raw material melt. apparatus.   The SiC single crystal manufacturing apparatus according to claim 1, wherein the heat insulating material has an annular shape.   The SiC single crystal manufacturing apparatus according to any one of claims 1 to 3, wherein the heat insulating material includes carbon fiber.   The SiC single crystal manufacturing apparatus according to claim 1, wherein the heat insulating material is made of carbon felt.   A graphite crucible for containing a raw material melt serving as a raw material for SiC single crystal, a heating means arranged around the graphite crucible, and a seed crystal holding arranged so as to be vertically movable above the graphite crucible A SiC single crystal, wherein a heat insulating material is disposed on the inner wall of the graphite crucible so that they do not contact at least part of a portion where the inner wall of the graphite crucible and the liquid surface of the raw material melt contact each other A SiC single crystal is grown under the seed crystal by immersing the seed crystal held at the lower end of the seed crystal holding part in the raw material melt in the graphite crucible using a manufacturing apparatus, A method for producing a SiC single crystal.   The method according to claim 6, wherein the heat insulating material is arranged on the entire circumference of the inner wall of the graphite crucible so that the inner wall of the graphite crucible does not contact the liquid surface of the raw material melt.   The method according to claim 6 or 7, wherein the shape of the heat insulating material is an annular shape.   The method according to claim 6, wherein the heat insulating material includes carbon fibers.   The method according to claim 6, wherein the heat insulating material is made of carbon felt.