Silicon carbide powder: the substrate sheet obtained by silicon carbide crystal processing, after subsequent processes such as epitaxy and ion implantation, is finally made into devices and modules, which are widely used in high-temperature, high-power, and high-frequency fields. Compared with silicon substrates, silicon carbide has a large band gap, high saturation electron mobility, strong breakdown field and high thermal conductivity. It is one of the most potential semiconductor materials in power electronics and radio frequency.
The main growth methods of silicon carbide crystals are the modified Rayleigh method (seed crystal sublimation method/PVT), high-temperature chemical vapor deposition method (htcvd) and liquid phase method (tssg). Because the gas phase method and the liquid phase method are currently in the research and development and optimization stage due to reasons such as high cost and small growth size, among the crystal growth methods, most enterprises use the sublimation method.
Silicon carbide powder
So far, it has been proposed to combine a silicon source (specifically ethyl silicate) which is liquid at average temperature, a carbon source (specifically phenolic resin) which is liquid at average temperature, and a catalyst capable of dissolving the carbon source (specifically ethyl silicate). Acid) mixing method to produce high-purity silicon carbide micro powder. Specifically, silicon carbide powder is produced by heating a mixture containing a silicon source, a carbon source, and a catalyst.
Silicon carbide (SiC) has high temperature strength and excellent wear resistance, oxidation resistance, corrosion resistance and creep resistance. Silicon carbide has a β phase with a cubic crystal structure and an α phase with a hexagonal crystal structure. The β phase is stable at temperatures between 1400°C and 1800°C, and the α phase forms above 2000°C.
Silicon carbide is widely used in industrial structures and more recently in the semiconductor industry. In order to use silicon carbide in single crystal growth, granular silicon carbide powder with a uniform particle size distribution is required. Granular silicon carbide powder can be obtained by annealing fine silicon carbide powder under predetermined conditions.
In the case of using maleic acid as the catalyst, the sulfur content contained in the silicon carbide powder was lower than in the case of using toluenesulfonic acid as the catalyst. Therefore, the use of maleic acid as a catalyst ensures the production of silicon carbide powder suitable for the field of semiconductors with sulfur as an impurity.
In addition, in order to produce silicon carbide powder with an average particle diameter of 100 to 200 μm, a technique of heating a mixture containing a silicon source, a carbon source, and a catalyst in two stages has also been proposed. In addition, it is also known that when the ratio of carbon contained in the carbon source of silicon carbide powder to silicon contained in the silicon source (hereinafter referred to as C/Si) is greater than 2.0 and less than 2.5, the amount can reduce free carbon.