Effect of Temperature on the Deposition Rate and Bending Strength Characteristics of Chemical Vapor Deposited Silicon Carbide Using Methyltrichlorosilane

The effects of deposition temperature on chemical vapor deposited silicon carbide (CVD-SiC) were studied to obtain high deposition rates and excellent bending strength characteristics. Silicon carbide prepared at 1250 similar to 1400 degrees C using methyltrichlorosilane(MTS : CH3SiCl3) by hot-wall CVD showed deposition rates of 95.71 similar to 17.2 mu m/hr. The rate-limiting reaction showed the surface reaction at less than 1300 degrees C, and the mass transfer dominant region at higher temperature. The activation energies calculated by Arrhenius plot were 11.26 kcal/mole and 4.47 kcal/mole, respectively. The surface morphology by the deposition temperature changed from 1250 degrees C pebble to 1300 degrees C facet structure and multi-facet structure at above 1350 degrees C. The cross sectional microstructures were columnar at below 1300 degrees C and isometric at above 1350 degrees C. The crystal phases were all identified as beta-SiC, but (220) peak was observed from 1300 degrees C or higher at 1250 degrees C (111) and completely changed to (220) at 1400 degrees C. The bending strength showed the maximum value at 1350 degrees C as densification increased at high temperatures and the microstructure changed from columnar to isometric. On the other hand, at 1400 degrees C, the increasing of grain size and the direction of crystal growth were completely changed from (111) to (220), which is the closest packing face, so the bending strength value seems to have decreased.