Why choose SiC-coated graphite susceptors?

Graphite susceptor is one of the essential parts in the MOCVD equipment, is the carrier and the heater of the wafer substrate. Its properties of thermal stability and thermal uniformity play a decisive role in the quality of wafer epitaxial growth, which directly determines the uniformity and purity of the layer materials, in a result its quality directly affects the preparation of epitaxy. In the meanwhile, with the increase in the number of uses and changes in working conditions, it is very easy to lose, and belongs to the consumables. Graphite's excellent thermal conductivity and stability make it a good advantage as a base component for MOCVD equipment. However, if only pure graphite is used, it will face some problems. There will be corrosive gas and metal organic residue in the production process, and the graphite base will corrode and drop off the powder, which greatly reduces the service life of the graphite susceptor, and the fallen graphite powder will also cause pollution to the chip, so in the preparation process of the base also These problems need to be solved during the preparation of the base. The coating technology can provide surface powder fixation, enhance thermal conductivity, and equalize thermal distribution, which becomes the main technology to solve this problem. The main technology is to solve this problem. According to the application environment and requirements of graphite susceptors, the surface coating should have the following characteristics.

High densities and full wrapping: the graphite base as a whole is in a high temperature, corrosive working environment, the surface must be fully wrapped, while the coating must have good densities to play a good protective role.

Good surface flatness: As the graphite base used for single crystal growth requires a very high surface flatness, the original flatness of the base must be maintained after the coating is prepared, i.e. the coating surface must be uniform.

Good bonding strength: Reducing the difference of thermal expansion coefficient between graphite base and coating material can effectively improve the bonding strength between them, and the coating is not easy to crack after high and low temperature thermal cycles.

High thermal conductivity: High quality chip growth requires fast and uniform heat from the graphite base, so the coating material should have high thermal conductivity.

High melting point, high temperature oxidation and corrosion resistance: The coating should be able to work stably in high temperature and corrosive working environments.