Seeded single crystal silicon carbide growth and resulting crystals

In a method of producing a high quality bulk single crystal of silicon carbide in a seeded growth system, and in the absence of a solid silicon carbide source, the improvement comprising:

• conforming the seed holder-facing surface of the seed crystal and the shape of the seed-holder to one another by preventing any gap between the seed and the seed-holder from exceeding 10 μm.

In a method of producing a high quality bulk single crystal of silicon carbide in a seeded growth system, and in the absence of a solid silicon carbide source, the improvement comprising lapping both sides of the seed crystal prior to growth.

In a method of producing a high quality bulk single crystal of silicon carbide in a seeded growth system, and in the absence of a solid silicon carbide source, the improvement comprising:

• maintaining a flat to slightly convex growth surface during the crystal growth while avoiding localized regions of undesired curvature within the first 10 mm of growth over the useable area of the crystal.

In a method of producing a high quality bulk single crystal of silicon carbide in a seeded growth system, and in the absence of a solid silicon carbide source, the improvement comprising:

• separating the rear of the silicon carbide crystal from the seed holder by an amount sufficient for radiative heat transfer to dominate over conductive heat transfer between the seed and the seed holder.

In a method of producing a high quality bulk single crystal of silicon carbide in a seeded growth system, and in the absence of a solid silicon carbide source, the improvement comprising:

• growing the bulk single crystal from a seed crystal with a seed holder-facing surface that deviates from flat by no more than 10 microns.

In a method of producing a high quality bulk single crystal of silicon carbide in a seeded growth system, and in the absence of a solid silicon carbide source, the improvement comprising:

• positioning the seed crystal for growth on a seed holder that deviates from flat by no more than 10 microns.

In a method of producing a high quality bulk single crystal of silicon carbide in a seeded growth system, and in the absence of a solid silicon carbide source, the improvement comprising growing the bulk single crystal on a seed crystal that is at least 1 millimeter thick.

In a method of producing a high quality bulk single crystal of silicon carbide in a seeded growth system, and in the absence of a solid silicon carbide source, the improvement comprising:

• positioning the seed crystal in a crucible while exerting minimal torsional forces on the seed crystal to thereby prevent torsional forces from warping or bowing the seed crystal in a manner that that would otherwise encourage sublimation from the rear of the seed crystal or undesired thermal differences across the seed crystal.

In a method of producing a high quality bulk single crystal of silicon carbide in a seeded growth system, and in the absence of a solid silicon carbide source, the improvement comprising:

• positioning a seed crystal on the seed holder with a low porosity backing material that provides a vapor barrier to silicon carbide sublimation from the seed and that minimizes the difference in thermal conductivity between the seed and the backing material to minimize or eliminate temperature differences across the seed and likewise minimize or eliminate vapor transport from the rear of the seed that would otherwise initiate and propagate defects in the growing crystal.

In a method of producing a high quality bulk single crystal of silicon carbide in a seeded growth system, and in the absence of a solid silicon carbide source, the improvement comprising:

• annealing the seed holder prior to crystal growth to prevent the seed holder from significant distortion during crystal growth and thereby minimize or eliminate temperature differences across the seed that would otherwise tend to initiate and propagate defects in the growing crystal;
• and
• thereafter initiating seeded growth with seed crystal.

In a method of producing a high quality bulk single crystal of silicon carbide in a seeded system, and in the absence of a solid silicon carbide source, the improvement comprising applying organic materials to a carbon seed-holder to improve the thermal uniformity of the seed holder under growth conditions.

In a seeded growth method for producing a high quality bulk single crystal of silicon carbide, and in the absence of a solid silicon carbide source, the improvement comprising selectively matching the coefficient of thermal expansion of the seed holder to the coefficient of thermal expansion of the silicon carbide seed.

In a seeded growth method for producing a high quality bulk single crystal of silicon carbide, and in the absence of a solid silicon carbide source, the improvement comprising positioning the seed on the seed holder with a high temperature adhesive.