Method for synthesizing low-nitrogen high-purity silicon carbide powder

Abstract

The invention discloses a method for synthesizing low-nitrogen high-purity silicon carbide powder, and relates to the technical field of silicon carbide synthesis. The method comprises the steps of filling the raw material powder into a crucible with an exhaust hole, putting the crucible into a furnace, vacuumizing a furnace chamber, and heating; then injecting high-purity H2 into the furnace chamber to 750-850 mbar, and then vacuumizing the furnace chamber to 4.5*10<-6>-5.5*10<-6>mbar; and repeating for multiple times, heating the furnace chamber, injecting high-purity Ar and H2 into the furnace chamber according to the flow ratio of (9-10.5): 1, carrying out synthetic reaction and conversion synthetic reaction, and cooling to room temperature under the protection of Ar and H2 after the reaction is finished. The nitrogen concentration in the powder synthesis process can be effectively reduced, and the powder purity is improved; and the mixed raw materials are effectively prevented from escaping from the crucible in the powder synthesis process, and the reaction efficiency of the powder is improved.

Description

technical field [0001] The invention relates to the technical fields of the electronic industry and semiconductor materials, in particular to the technical field of silicon carbide synthesis, and in particular to a method for synthesizing low-nitrogen high-purity silicon carbide powder. Background technique [0002] High-purity semi-insulating silicon carbide single crystal substrates are the key materials for electronic components. To grow high-purity semi-insulating single crystal substrates with high resistivity and excellent electrical properties, the content of donor impurity nitrogen in the substrate must be controlled at a low level. . Fundamentally, it is necessary to reduce the nitrogen content in the high-purity silicon carbide powder used for growing single crystals. At present, the self-propagating method is generally used to synthesize high-purity silicon carbide powder with high-purity graphite powder and high-purity silicon powder as raw materials. However, s...

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Problems solved by technology

At present, the self-propagating method is generally used to synthesize high-purity silicon carbide powder with high-purity graphite powder and high-purity silicon powder as raw materials. However, since the particle size of high-purity graphite powder and high-purity silicon powder is small, at the micron level, so , the surface of the powder will absorb nitrogen. In addition, the powder accumulation is relatively dense and the mixed raw materials are placed in a graphite crucible with better airtightness for powder synthesis, making it difficult for the nitrogen mixed in the raw materials to escape from the graphite crucible during the synthesis process. , so that it is inevitably incorporated into the crystal lattice of the synthesized silicon carbide powder, resulting in high nitrogen content in the silicon carbide powder, which cannot meet the requirements for the growth of high-purity semi-insulating silicon carbide single crystal

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