90% silicon carbide fine powder: 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 advancement of microelectronics technology, new electronic devices are moving towards high voltage resistance, large capacity and high frequency. , develop in the direction of reliability and integration, Sic single crystal, as the third generation of wide bandgap semiconductor material, has properties such as wide bandgap, high thermal conductivity, high electron saturation migration rate, high breakdown electric field, etc., and is considered to be an ideal choice for manufacturing optoelectronics. It is an ideal semiconductor material for devices, high-frequency high-power devices, and high-temperature electronic devices. It is widely used in white light lighting, optical storage, screen display, aerospace, oil exploration, automation, radar and communications, automotive electronics, etc.
Due to these excellent properties of 90% silicon carbide fine powder, many countries have invested a lot of money in in-depth research on it in recent years, and have made significant progress in silicon carbide crystal growth technology, key device processes, optoelectronic device development, and silicon carbide integrated circuit manufacturing. A breakthrough was achieved. At present, the PVT (physical vapor transport) method is generally used to prepare Sic single crystals, and the purity of 90% silicon carbide fine powder Sic powder and other parameters are very important for SiC single crystals prepared by the PVT method, especially N-type and high-purity semi-insulating single crystals. The crystal quality and electrical properties of the crystal play a crucial role.
Generally speaking, there are three main methods for synthesizing 90% silicon carbide fine SiC powder: Acheson method, organic synthesis method and self-propagation method. In the Acheson method, SiO2 is reduced by C under the action of high temperature and strong electric field, first generating β-SiC, and then transforming into a-SiC at high temperature. The SiC powder synthesized by this method requires processes such as crushing and pickling. The impurity content is high, and its purity cannot reach the level of growing semiconductor single crystals.
The organic synthesis method is mainly used to prepare nano-scale SiC powder. There are many impurity elements in the synthesized raw materials. Although high-purity SiC powder with high purity can be obtained through subsequent processing, the subsequent processing process is complicated and the collection of fine powder is difficult, so it is not suitable. It is used in mass production and is prone to produce harmful substances to the human body. In addition, the particle size of the 90% silicon carbide fine SiC powder synthesized by this method is too small, which will seriously affect the crystal quality of SiC single crystal. The high-temperature self-propagation method uses the self-conduction of the reaction heat of substances to cause chemical reactions between substances and form high-temperature synthesis reactions of compounds in a very short time.
The self-propagation method is a method in which C powder and Si powder react directly to form SiC. At present, this method has been widely used in the preparation of high-purity 90% silicon carbide fine powder SiC powder. This method uses high-purity C powder and Si powder to go through a pretreatment process first, and then synthesizes high-purity silicon carbide powder through a high-temperature synthesis process. In the above-mentioned existing methods, high-purity carbon materials and high-purity Si powder are mixed, and 90% silicon carbide fine powder SiC powder is synthesized in an environment filled with inert gas or a mixed gas of inert gas and reducing gas.
Since the high-purity carbon material and high-purity Si powder used have small particle sizes and small gaps between each other, after they are mixed and put into the crucible, it is difficult to completely remove the gas inside the raw materials under vacuum. In addition, due to the selected inert gas and Although the reducing gas is very pure, it still contains a small amount of impurity gas. Therefore, when synthesizing silicon carbide powder in an environment filled with inert gas or a mixture of inert gas and reducing gas, the impurity gas elements will be in the reaction process of C and Si. mixed in, thus affecting the purity of the synthesized SiC powder.
In addition, although the secondary synthesis and third synthesis of SiC powder will improve the purity of the powder, the process is complicated and increases the cost of powder preparation. This method can only synthesize β-SiC (3C phase SiC), and the synthetic powder The material has a single phase, making it difficult to select the crystal form of the powder when growing silicon carbide single crystal. In view of the shortcomings of the existing technology for synthesizing 90% silicon carbide fine powder, it is necessary to provide a method for preparing high-purity silicon carbide powder that can achieve ultra-high purity SiC powder and has a simple process.