Silicon carbide crystal and preparation method thereof

Abstract

The invention discloses a preparation method of a silicon carbide crystal, and belongs to the field of semiconductor material preparation. The method comprises the steps: providing a reaction cavity, a crystal growth cavity and a material removing mechanism, wherein the reaction cavity comprises a raw material cavity and a waste material cavity, and a silicon carbide raw material is put into the raw material cavity; executing the crystal growth stage: controlling crystal growth conditions, conveying raw material gas generated by sublimation of the raw materials in the raw material cavity to the crystal growth cavity through a gas phase conveying channel for crystal growth, when the sublimation rate of the silicon carbide raw materials is a first sublimation rate, starting a material removing mechanism so that the material removing mechanism transfers waste generated after sublimation of the raw materials in the reaction cavity to a waste cavity, enabling remaining raw materials in the raw material cavity to continue to sublimate under the crystal growth condition for crystal growth, enabling the material removing mechanism to continue to remove materials till crystal growth is finished, and preparing the silicon carbide crystals. The sublimation rate and the utilization rate of the raw materials can be improved, and the defects of crystals are reduced.

Description

technical field [0001] The application relates to a silicon carbide crystal and a preparation method thereof, belonging to the field of semiconductor material preparation. Background technique [0002] At present, in the preparation of silicon carbide crystals, physical vapor transport (PVT method for short) technology is mainly used, which decomposes silicon carbide raw materials into gas phase components Si by sublimation. m C n Finally, driven by the axial temperature gradient, it is transported to the seed crystal and grows into silicon carbide crystals. The PVT method is a complex process, and many parameters must be comprehensively controlled, such as growth temperature, temperature gradient, direct distance between the seed crystal and the growth material, gas pressure, etc. If any parameter is not well controlled, the stability of crystal growth Sex will be destroyed. [0003] In the later stage of the growth of silicon carbide crystals, the silicon carbide raw ma...

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Problems solved by technology

Graphitization of silicon carbide raw materials is a common instability factor, which will increase the possibility of crystal graphitization and the formation of other defects, so that the crystal growth rate is largely limited

[0004] The current solution is to add additional solid silicon to the graphite crucible, which can compensate for the lack of silicon in the growth material and prevent the graphitization of the growth material to a certain extent, but this will lead to the formation of liquid silicon droplets and the formation of polymorphic structures. The second is to use tantalum crucibles to create an environment for adsorbing carbon, which can significantly inhibit the graphitization of growth raw materials, but the price of tantalum crucibles is too high to be used on a large scale

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