Technological development of preparation of silicon carbide substrate

We established the synthesis technologies of silicon carbide (SiC) with large (3 inch diameter) and flat surface and good electric properties. The chemical vapor deposition (CVD) was used as a control method of crystal growth. The pretreatment of carbonization of surface of silicon wafer, the seed crystal substrate, was carried out by propane gas to form the very thin film of SiC buffer layer. The best condition of crystallization was 100 Torr of mixture gas of silan and propane at 1300degC. Under the best conditions, SiC single crystal with mirror surface of 3 inch silicon wafer was obtained. The thickness of crystal was 20 μm. For example, p-type crystal with aluminum showed about 3x1016/cm3 carrier concentration and 30 cm2/Vs mobility. They are the best values reported. MOSFET, a transistor used synthesized cubic crystal SiC substrate, was explained. (S.Y.)