We have investigated formation of SiC/Si multilayers on SI(I 00) by supersonic free jet CVD utilizing single gas source, CH3SiH3. The H-2 diluted 10% CH3SiH3 gas was introduced into the chamber by using a pulse valve. At first, the substrate temperature was set at 850 degreesC and a SiC layer was grown on Si(100). Then the substrate temperature was reduced to 400 similar to 600 degreesC and a Si layer was formed using a tungsten hot filament on the SIC layer. The Si layer was amorphous at the substrate temperature of 400 degreesC while polycrystalline Si was formed at 600 degreesC. SiC/Si/SiC multilayer structures were Successfully grown by repeating the CH3SiH3 jet exposures at 850 degreesC and 600 degreesC.