Silicon nitride film was deposited on silicon by gas phase reaction between SiH4 and NH3 using N2 as the carrier gas and a horizontal resistance-heated furnace at the temperature range of 650 to 950°C. The higher the substrate temperature became, the larger the wave number of the infrared, which corresponds to the maximum absorption. Film deposited at lower temperature always showed the hysteresis of C-V curve, but it almost disappeared by elevating substrate temperature and supplying much amount of ammonia. MNS diode was very stable to the BT-treatment even if it was intentionally contaminated with NaOH. Interface charge density was nearly 1.5×1012e/cm2 which was little dependent of surface treatments before depositing the film, and seemed to be almost determined by the positive charge in nitride film. C-V curve of the diode showed the frequency dependence, which was due to the accumulation of electrons in nitride film near the interface.