Method for producing sic single crystal
In SiC single crystal production by the solution process, an alloy of silicon (Si) and a metallic element M that increases the solubility of carbon (C) is pre-impregnated into a SiC sintered body having a relative density of 50 to 90%, following which Si and M are placed in a SiC crucible made of the SiC sintered body and the Si and M within the SiC crucible are melted, forming a Si—C solution. With heating, SiC from the SiC sintered body dissolves into the Si—C solution, efficiently supplying Si and C to the Si—C solution. As a result, Si and C are supplied uniformly and in the proper amount from all areas of contact between the SiC crucible and the Si—C solution, enabling a high-quality SiC single crystal to be stably produced over a long time at a rapid growth rate.
1 . A method for producing a SiC single crystal, comprising the following order of:
providing a SiC crucible formed of a SiC sintered body having a relative density of from 50 to 90% and pores, wherein an alloy has been impregnated into the pores of the SiC sintered body in advance, the alloy including first silicon and a first metallic element M that increases a solubility of carbon,
placing second silicon and a second metallic element M in the SiC crucible,
heating the SiC crucible to melt the second silicon and the second metallic element M, into which the first silicon and carbon originating from SiC in the SiC crucible are supplied, thereby forming a Si—C solution, and
contacting a SiC seed crystal with a top portion of the Si—C solution so as to grow the SiC single crystal on the SiC seed crystal,
wherein the first metallic element M comprises one or both of at least one type of a metallic element M1 selected from the group consisting of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho and Lu, and wherein the second metallic element M comprises at least one type of another metallic element M2 selected from the group consisting of Ti, V, Cr, Mn, Co, Ni and Cu.
2 . The production method of claim 1 , wherein each of the first metallic element M and the second metallic element M comprises both the metallic element M1 and said another metallic element M2, and a total content of the first metallic element M and the second metallic element M in the Si—C solution is from 1 to 80 at %.
3 . The production method of claim 2 , wherein a content of the metallic element M1 in the Si—C solution is at least 10 at % of a total amount of silicon and M, and a content of said another metallic element M2 in the Si—C solution is at least 1 at % of the total amount of silicon and M.
4 . The production method of claim 1 , wherein the SiC sintered body has an oxygen content of 100 ppm or less.
5 . The production method of claim 1 , wherein growth of the SiC single crystal is carried out at a temperature for the Si—C solution of between 1,300 and 2,300° C.
6 . The production method of claim 1 , wherein the method is carried out with the SiC crucible held within a second crucible made of a heat-resistant carbon material.
7 . The production method of claim 1 , wherein a growth rate of the SiC single crystal is 10 μm/hr or more.
8 . The production method of claim 1 , wherein a growth rate of the SiC single crystal is 100 μm/hr or more.