Silicon nitride films have been successfully deposited at a temperature as low as 300°C by chemical-vapor-deposition using tctra-silane (Si4 H10) and hydrogen azidc (HN3). Atomic ratio (N/Si) of the film deposited at 400°C was 1.47, i.e., the film was N-rich. Total hydrogen content was about 25atomic%. The breakdown-field strength was 6.5MV/cm at leakage-current density of 1μA/cm2, and the low-field resistivity was more than 1015 Ωcm. Similar electrical characteristics were obtained from films deposited at a temperature range between 300°C and 500°C. Amorphous silicon thin-film transistors equipped with this film as the gate dielectric showed good transfer characteristics.