SiC single crystal production apparatus

Abstract

The invention provides a SiC single crystal production apparatus with high uniformity of temperature distribution in a crystal growth vessel. The SiC single crystal production apparatus includes a crystal growth vessel containing SiC raw material; an insulation part covering the periphery of the crystal growth vessel; a heater used to heat the crystal growth vessel; and a holding member used to hold the crystal growth vessel, wherein the crystal growth vessel is held in a suspended state by the holding member.

Claims

1. A SiC single crystal production apparatus, comprising: a crystal growth vessel containing a SiC raw material; an insulation part covering the periphery of the crystal growth vessel; a heater used to heat the crystal growth vessel; and a holding member used to hold the crystal growth vessel, wherein the holding member comprises; a pedestal; two struts fixed to the pedestal; a first end of a projection being provided in the strut, and a second end of the projection engaging a central portion of a side surface of the crystal growth vessel so as to hold the crystal growth vessel in a floating state from the pedestal and thereby allow the crystal growth vessel to move freely, and wherein the heater is located more outside the crystal growth vessel than the holding member, and the heater is located more outside the crystal growth vessel than the insulation part.

2. The SiC single crystal production apparatus according to claim 1, wherein the second end of the projection is inserted into a recess in the side surface of the crystal growth vessel.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a schematic cross-sectional view of the SiC single crystal production apparatus according to the first embodiment of the present invention.

(2) FIG. 2 is a schematic cross-sectional view of the SiC single crystal production apparatus according to a second embodiment of the present invention.

(3) FIG. 3 is a schematic cross-sectional view of the SiC single crystal production apparatus according to a third embodiment of the present invention.

(4) FIG. 4 is a schematic cross-sectional view of the SiC single crystal production apparatus according to a fourth embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

(5) Hereinafter, the SiC single crystal production apparatus according to an embodiment of the present invention will be described in detail with reference to the drawings as appropriate. In the drawings used in the following description, in order to make the characteristics of the present invention easier to understand, there are cases where the characteristic parts are enlarged for the sake of convenience, and the dimensional ratios of the respective components are different from the actual ones. The materials, dimensions, and the like exemplified in the following description are merely examples, and the present invention is not limited to these and can be implemented with appropriate modifications within the scope of the effects of the present invention.

(6) The SiC single crystal production apparatus of the present invention includes a crystal growth vessel containing a SiC raw material, an insulation part covering the periphery of the crystal growth vessel, a heater used to heat the crystal growth vessel, and a holding member used to hold the crystal growth vessel. The crystal growth vessel is held in a suspended state by the holding member.

(7) In the present invention, “the crystal growth vessel is held in a suspended state” means that the crystal growth vessel is held in a state where a space exists between the bottom surface side and the apparatus. The crystal growth vessel may or may not move freely. As a method of holding the crystal growth vessel in the suspended state, it is not particularly limited as long as the crystal growth vessel is held in a state where a space exists between the bottom surface side and the apparatus.

(8) The holding member preferably includes a first holding part fixed to the SiC single crystal production apparatus, a second holding part fixed to the first holding part, and an engaging part engaged with the crystal growth vessel and the second holding part. The crystal growth vessel is held in a suspended state by engaging the engaging part with the side surface of the crystal growth vessel.

(9) Examples of the holding member include the holding member 40a of the first embodiment (described later) shown in FIG. 1 and the holding member 40b of the second embodiment (described later) shown in FIG. 2. Examples of the first holding part include a pedestal 41a shown in FIG. 1 and a pedestal 41b shown in FIG. 2. Examples of the second holding part include the strut 42b shown in FIG. 1 and the strut 42b shown in FIG. 2 Examples of the engaging part include a projection 43a shown in FIG. 1 and a projection 43b shown in FIG. 2.

First Embodiment

(10) FIG. 1 is a schematic cross-sectional view of the SiC single crystal production apparatus according to the first embodiment of the present invention.

(11) A SiC single crystal production apparatus 101 shown in FIG. 1 includes a crystal growth vessel 10, an insulation part 20, a heater 30, and a holding member 40a.

(12) The crystal growth vessel 10 has a raw material storage part 11 and a lid part 12. The raw material storage part 11 accommodates a SiC raw material 1. The lid part 12 has a seed crystal holding part 13 for holding a seed crystal 2. As a material for the raw material storage part 11 and the lid part 12, for example, graphite, tantalum carbide, or the like can be used.

(13) The insulation part 20 is arranged around the crystal growth vessel 10 so as to cover the crystal growth vessel 10. The insulation part 20 is not particularly limited, and a well-known insulation part utilized as insulation part for a SiC single crystal production apparatus, such as a carbon fiber felt, can be used. A through hole 21 is formed in the top part 20a of the insulation part 20, and the temperature of the lid part 12 can be measured through the through hole 21 by using a non-contact temperature measuring device. A radiation thermometer can be used as the non-contact temperature measuring device.

(14) The heater 30 is not particularly limited, and the well-known heater currently utilized as a heater for SiC single crystal production apparatus, such as a resistance heater and an induction heater, can be used. The heater 30 shown in FIG. 1 is an induction heater using a high-frequency coil.

(15) The holding member 40a includes a pedestal 41a, a strut 42a fixed to the pedestal 41a, and a projection 43a provided in the strut 42a. The pedestal 41a is disposed below the crystal growth vessel 10, and the strut 42a extends upward. A recess 16 is provided on the side surface of the crystal growth vessel 10. By inserting the projection 43a of the strut 42a into the recess 16 of the crystal growth vessel 10 and engaging the holding member 40a and the crystal growth vessel 10, the crystal growth vessel 10 is held in a floating state, or in a suspended state from the pedestal 41a. As a material of the pedestal 41a and strut 42a, for example, graphite, tantalum carbide, or the like can be used. The holding member 40a is held by a main shaft 44 a that penetrates the bottom of the insulation part 20.

(16) In the SiC single crystal production apparatus 101 of this embodiment, the crystal growth vessel 10 is heated by the heater 30. By heating the crystal growth vessel 10, the SiC raw material 1 accommodated in the raw material storage part 11 of the crystal growth vessel 10 is sublimated to generate sublimation gas. The sublimation gas contacts the seed crystal 2 held by the seed crystal holding part 13 of the lid part 12 and grows the seed crystal 2 into a SiC single crystal.

(17) In the SiC single crystal production apparatus 101 of this embodiment, the crystal growth vessel 10 is held in the suspended state by the holding member 40a. For this reason, it is possible to suppress the heat of the heated crystal growth vessel 10 from being radiated to the outside via the pedal 41a by the heater 30. Therefore, the uniformity of the temperature distribution in the crystal growth vessel 10 is improved. Further, the uniform temperature distribution in the crystal growth vessel 10 makes it difficult for the sublimation gas generated in the crystal growth vessel 10 to recrystallize in the center of the crystal growth vessel 10. It becomes possible to stably produce a SiC single crystal having a large diameter.

Second Embodiment

(18) FIG. 2 is a schematic cross-sectional view of SiC single crystal production apparatus according to the second embodiment of the present invention.

(19) The SiC single crystal production apparatus 102 shown in FIG. 2 is different from the SiC single crystal production apparatus 101 of the first Embodiment in that the pedestal 41b of the holding member 40b is arranged above the crystal growth vessel 10, and the strut 42b extends downward. In addition, the parts of the SiC single crystal production apparatus 102 shown in FIG. 2, which are the same as the parts of the SiC single crystal production apparatus 101 of the first Embodiment, are denoted by the same reference numerals, and description thereof is omitted.

(20) In the SiC single crystal production apparatus 102 of the present embodiment, by inserting the projection 43b provided in the strut 42b of the holding member 40b into a recess 16 of the crystal growth vessel 10 and engaging the holding member 40b and the crystal growth vessel 10, the crystal growth vessel 10 is held in a suspended state from the pedal 41b. For this reason, it can prevent the heat of the heated crystal growth vessel 10 from being thermally radiated outside via the pedal 41b by the heater 30. Therefore, the uniformity of the temperature distribution in the crystal growth vessel 10 is improved. Further, the uniform temperature distribution in the crystal growth vessel 10 makes it difficult for the sublimation gas generated in the crystal growth vessel 10 to recrystallize in the center of the crystal growth vessel 10. It becomes possible to produce a SiC single crystal with a large diameter in a stable manner. The holding member 40b is held by a main shaft 44b penetrating the top part of the insulation part 20.

Third Embodiment

(21) FIG. 3 is a schematic sectional view of SiC single crystal production apparatus according to the third embodiment of the present invention.

(22) The SiC single crystal production apparatus 103 shown in FIG. 3 is different from the SiC single crystal production apparatus 101 of the first embodiment in that a sub-heater 45 is provided in the vicinity of the pedal 41a of the holding member 40a. In addition, the parts of the SiC single crystal production apparatus 103, which is the same as the parts of the SiC single crystal production apparatus 101 of the first Embodiment, are denoted by the same reference numerals, and description thereof is omitted.

(23) In the SiC single crystal production apparatus 103 of the present embodiment, by using the sub-heater 45 provided in the vicinity of the pedal 41a, the bottom of the crystal growth vessel 10 that is difficult to heat with the heater 30 disposed on the side of the crystal growth vessel 10 can be heated. Therefore, the uniformity of temperature distribution in the crystal growth vessel 10 is further improved by the effect of suppressing heat dissipation by holding the crystal growth vessel 10 in the suspended state and the heating effect by using the sub-heater 45. Further, the uniform temperature distribution in the crystal growth vessel 10 makes it difficult for the sublimation gas generated in the crystal growth vessel 10 to recrystallize in the center of the crystal growth vessel 10. It becomes possible to produce a SiC single crystal with a large diameter.

Fourth Embodiment

(24) FIG. 4 is a schematic cross-sectional view of the SiC single crystal production apparatus according to the fourth embodiment of the present invention.

(25) The SiC single crystal production apparatus 104 shown in FIG. 4 is different from the SiC single crystal production apparatus 101 of the first embodiment in that an induction heating part 46 is provided in the pedal 41a of the holding member 40a. In addition, the parts of the SiC single crystal production apparatus 104 of this embodiment that are the same as the parts the SiC single crystal production apparatus 101 of the first Embodiment are denoted by the same reference numerals, and description thereof is omitted.

(26) In the SiC single crystal production apparatus 104 of this embodiment, the induction heating part 46 provided in the pedal 41a can heat the bottom of the crystal growth vessel 10 that is difficult to heat with the heater 30 disposed on the side of the crystal growth vessel 10. Therefore, the uniformity of temperature distribution in the crystal growth vessel 10 is further improved by the effect of suppressing heat dissipation by holding the crystal growth vessel 10 in the suspended state and by the heating effect of the induction heating part 46. Further, the uniform temperature distribution in the crystal growth vessel 10 makes it difficult for the sublimation gas generated in the crystal growth vessel 10 to recrystallize in the center of the crystal growth vessel 10. It becomes possible to produce a SiC single crystal with a large diameter.

(27) As mentioned above, although several embodiments of this invention were described, the invention is not limited to them. It is possible to implement suitable changes within the scope of the effect of this invention. For example, in the SiC single crystal production apparatuses 101 to 104 of the first to fourth embodiments described above, the holding members 40a and the crystal growth vessel 10 are engaged by inserting the projections 43a of the struts 42a into the recess 16 of the crystal growth vessel 10, and the holding members 40b and the crystal growth vessel 10 are engaged by inserting the projections 43b of the struts 42b into the recess 16 of the crystal growth vessel 10. However, there is no particular limitation on the method of engaging the holding members 40a and 40b with the crystal growth vessel 10. For example, projections may be provided on the side surfaces of the crystal growth vessel 10, recesses 16 may be provided in the struts 42a or 42b, and projections of the crystal growth vessel 10 may be inserted into the recesses 16 in the struts 42a or 42b. Further, projections may be provided on the side surfaces of the crystal growth vessel 10 and the struts 42a and 42b, so that the projections of the crystal growth vessel 10 and the projections of the struts 42a may be connected and the projections of the crystal growth vessel 10 and the projections of the struts 42b may be connected. The number of each of struts 42a and 42b may be three or more. When three or more struts 42a or 42b are used, it is preferable to arrange the struts at equal intervals.

(28) Further, in the SiC single crystal production apparatuses 101, 103, 104 of the first, third, and fourth embodiments, instead of providing the projection 43a in the strut 42a, a bump part is provided around the crystal growth vessel, and the lower surface of the bump part and the tip of the strut 42a may be directly connected to each other.

(29) Furthermore, in the SiC single crystal production apparatus 102 of the second embodiment, the main shaft 44b may be directly connected to the lid part 12 of the crystal growth vessel 10 as a holding member.

EXPLANATION OF REFERENCE NUMERALS

(30) 1 SiC raw material 2 seed crystal 10 crystal growth vessel 11 raw material storage part 12 lid part 13 seed crystal holding part 16 recess 20 insulation part 20a top part 21 through hole 30 heater 40a, 40b holding member 41a, 41b pedestal 42a, 42b strut 43a, 43b projection 44a, 44b main shaft 45 sub-heater 46 induction heating part 101, 102, 103, 104 SiC single crystal production apparatus