A combined structural and optical assessment of cubic (3C-) SiC thin films grown on Si (100) substrates by chemical vapor epitaxy (CVD) is presented. The CVD growth was performed at both atmospheric and low (100 Torr) pressure, using a vertical reactor. The CVD-grown 3C-SiC films with different growth time were characterized by X-ray diffraction, Raman scattering and Fourier transform infrared (FTIR) spectroscopy to be single crystalline with a high degree of crystal perfection. The film thickness was determined from FTIR spectra. Variations of X-ray, FTIR and Raman spectra with different growth conditions and film thicknesses are studied comparatively. Related problems are discussed.