Preparation method of high-purity silicon carbide powder for single crystal growth

Abstract

The invention discloses a preparation method of high-purity silicon carbide powder for single crystal growth, which belongs to the technical field of semiconductor materials. According to the technical scheme, high-purity graphite powder, high-purity Si powder and polytetrafluoroethylene powder are selected, mixed and then placed in a heating furnace, high-purity H2 is injected into a furnace cavity, and vacuumizing is conducted after the high-purity H2 is kept for a certain time; the heating furnace is heated to 850-990 DEG C, high-purity H2 is injected again, the temperature is kept for a certain time, vacuumizing is carried out again, then heating is carried out to 1000-1200 DEG C again, and a SiC synthesis reaction is performed to obtain high-purity beta-SiC powder; high-purity H2, high-purity Ar and high-purity HCl are continued to be injected into the furnace chamber, heated to 1900-2100 DEG C, and a conversion synthesis reaction is carried out to obtain high-purity alpha-SiC powder; the purity of the final silicon carbide powder is effectively improved by improving the environmental purity and limiting process parameters, and the method is suitable for single crystal growthof high-purity semi-insulating silicon carbide.

Description

technical field [0001] The invention relates to the field of power electronics industry and semiconductor materials, especially silicon carbide single crystal material, and more specifically relates to a method for preparing high-purity silicon carbide powder for growing high-purity semi-insulating silicon carbide single crystal. Background technique [0002] Power electronics is an important supporting technology in the field of national economy and national security. With the rapid development of the information industry and the progress of microelectronics technology, new electronic components are developing towards high voltage resistance, large capacity, high frequency, high reliability and high integration. As a third-generation wide-bandgap semiconductor material, SiC single crystal has properties such as wide bandgap, high thermal conductivity, high electron saturation migration rate, and high breakdown electric field. It is considered to be ideal for manufacturing op...

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Problems solved by technology

Due to the small particle size of the high-purity carbon material and the high-purity Si powder used, the gap between them is small, after mixing and putting into the crucible, it is difficult to completely remove the gas inside the raw material under vacuum. In addition, due to the selected high-purity carbon material Although the purity of high-purity Si powder is very high, it still contains a small amount of impurities. Therefore, when choosing to synthesize silicon carbide powder, impurity elements will be mixed in the reaction process of C and Si, thus affecting the purity of the synthesized SiC powder.

In addition, patents CN101302011A and CN103508454B disclose methods for secondary synthesis and tertiary synthesis of SiC powder, although this will improve the purity of the powder, but the process is complicated and increases the cost of powder preparation, while patent CN104828825A uses a low-temperature method to synthesize SiC powder It saves cost, but this method can only synthesize β-SiC (3C phase SiC), and the synthetic powder has a single phase, which is difficult to meet the choice of powder crystal form when growing silicon carbide single crystal

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