Films of silicon nitride have been grown in an ultrahigh vacuum system by the reaction of silane with nitrogen remotely excited in a microwave plasma at pressures in the range 0.1–0.9 Torr with substrate temperatures in the range 70–350 °C. Growth rates have been determined as a function of silane–nitrogen flow ratio, pressure, microwave power, and substrate temperature in order to give some insight into the growth mechanism. Results indicate that the rate of film deposition is governed by the arrival rate of active nitrogen species at the surface. The films have been characterized by 15N nuclear reaction profiling and Rutherford backscattering analysis to determine the hydrogen, silicon, and nitrogen contents. Hydrogen contents are comparable to those obtained with parallel-plate plasma enhanced chemical vapor deposition reactors while near stoichiometric, nitrogen rich films can be obtained over a wide range of deposition parameters. Floating double probe measurements used to obtain the electron temperatures and ion densities verify that substrate bombardment by charged or energetic particles is not a factor in the growth of these films.