SiC films were deposited on Si(100) substrates by electron cyclotron resonance chemical vapor deposition at 500 degrees C using SiH4/CH4/H-2 gas mixtures. The chemical composition and crystalline microstructure were investigated by x-ray photoelectron spectroscopy and cross-sectional transmission electron microscopy, respectively. The film composition and microstructure are correlated to process variables. The deposition mechanism which controls the film characteristics is presented.