Preparation method of high-quality silicon carbide single crystal and silicon carbide single crystal

Abstract

The invention provides a preparation method of a high-quality silicon carbide single crystal. The method at least comprises the steps of charging, heating and crystal growth. The charging step comprises the following substeps of providing a crystal growth raw material to a thermal field. The crystal growth raw material comprises a first silicon carbide powder material and a mixed powder material containing a second silicon carbide powder material and a carbon powder material, and the mixed powder material is located below the bottom of the first silicon carbide powder material in a thermal field. According to the preparation method of the silicon carbide single crystal, the lower layer is the mixed powder containing the carbon powder and the silicon carbide powder, and the upper layer is the pure silicon carbide powder, so that the silicon-carbon ratio in the early stage of crystal growth is increased, the silicon atmosphere preferentially reacts with the carbon powder in the mixed powder, corrosion to the wall of a graphite crucible is effectively reduced, meanwhile, carbon particles can be prevented from being conveyed to a growth surface in the later period of crystal growth, and carbon inclusion defects generated in the early period and the later period of crystal growth are effectively reduced.

Description

technical field [0001] The application relates to the technical field of preparation of crystal materials, in particular to a method for preparing a high-quality silicon carbide single crystal and the silicon carbide single crystal. Background technique [0002] In the prior art, when using the PVT method to prepare silicon carbide single crystals, the silicon carbide seed crystal is usually fixed on the top of the graphite crucible, and the silicon carbide powder is placed inside the graphite crucible as a crystal growth raw material. The essence of the PVT method lies in the decomposition of silicon carbide powder, and the gas phase components of the decomposition mainly include Si, Si 2 C and SiC 2 . [0003] Therefore, the gas phase obtained after thermal decomposition of silicon carbide powder is a silicon-rich gas phase, that is, in the early stage of crystal growth, the partial pressure of the silicon atmosphere in the crucible is too high, and the silicon atmospher...

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Problems solved by technology

The above reaction process, on the one hand, will cause serious corrosion to the graphite crucible, on the other hand, in the early stage of crystal growth, a large amount of carbon particles will be transported to the growth surface, resulting in carbon inclusions in the early stage, and in the later stage of crystal growth, the carbonization of the bottom of the crucible The silicon raw material is severely carbonized due to the rapid sublimation of silicon, and the carbonized silicon carbide material is easily transported to the growth surface with the atmosphere, resulting in carbon inclusions in the later stage.

[0004] In the prior art, the formation of carbon inclusions is mostly reduced by improving the structure of the crucible or supplementing the silicon atmosphere during the preparation process, thereby improving the quality of silicon carbide crystals. However, the existing improvement methods are complicated and cumbersome to operate, and the quality of silicon carbide crystals is improved. The effect is not significant, which is not conducive to industrial production

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