The effects of CH4/SiH4 flow ratio and microwave power on the formation of SiC at 200 degreesC by electron cyclotron resonance chemical vapor deposition is investigated. When the CH4/SiH4 flow ratio is varied from 0.5 to 10, crystalline phase of films vary from polycrystalline silicon to polycrystalline P-SiC and finally to amorphous silicon carbide. However, as the microwave power increases from 300 to 1500 W. the film microstructure changes from polycrystalline Si to amorphous SiC. and finally to polycrystalline beta-SiC. The deposition mechanism which controls the film characteristics is also presented.