The composition and conduction of silicon nitride film formed by the reaction of SiH2Cl2and NH3at a low pressure were studied. In the range investigated, this film is amorphous N‐rich silicon nitride no matter what the growth conditions. Conduction at room temperature in a steady state was investigated by analyzing the charge distribution without using an average field approximation. Probable charge distribution in the nitride was derived from the thickness dependence of the applied voltage at a constant current and from the flat‐band voltage shift giving the interface fields. When current densityJ= 10−5A/cm−2, we obtainednt(0) = 3×1018cm−3, interface fieldsEs= 4.0×106V/cm, and the charge centroid &ohgr; = 210 A˚. The dynamic dielectric constant is calculated as &egr;d= 3.9 from the temperature dependence of conduction, using the average field approximation. The average field approximation is valid only at high temperatures.