Silicon nitride (SiNx) films were prepared with a gas mixture of SiH4, NH3 and H-2 on Si wafers at low temperatures using the catalytic chemical vapor deposition (Cat-CVD) method. For fixed flow-rates, properties for the SiNx films depending on substrate temperatures from 20 degrees C to 100 degrees C were investigated. The N/Si composition ratio depended little on the substrate temperature. When the substrate temperature was low, the refractive index decreased, the deposition rate increased slightly, the etch rate became large and the internal stress decreased. No variation appeared in the infrared absorption of the films before and after a pressure cooker test. It is found that highly moisture-resistant SiNx films without stress can be obtained at room temperature by using Cat-CVD. (c) 2005 Published by Elsevier B.V.