A thin 3C-SiC layer is formed heteroepitaxially by the carbonization of Si(100) surface at low temperatures by using an ultra-high vacuum electron cyclotron resonance chemical vapor deposition system. Substrate direct-current (DC) bias was an important parameter to affect the crystallinity of the thin films, which could control the flux or total dose of irradiating species, which were involved in the formation of the film. By controlling the substrate bias, the crystallinity changes from amorphous to crystalline. That means the flux or dose of the ions in the plasma affect the crystallinity of growing thin films. In case the substrate was biased positively, Reflection high-energy electron diffraction (RHEED) showed the formation of the heteroepitaxial SiC layer. This implies the importance of the control of total dose of impinging species. Axial plasma potential profiles were measured to investigate the energy of the ions impinging on the surface. RHEED showed the formation of crystalline 3C-SiC when a defect free, clean Si surface was provided by the H, plasma cleaning and a positive bias voltage was applied to the substrate during carbonization process. By two-step carbonization using the proper values of bias voltage and CH4/H-2 flow ratio, crystalline 3C-SiC could be formed at the substrate temperature of 600degreesC (C) 2003 Elsevier Science B.V. All rights reserved.