The effect of deposition temperature on the physical properties of SiOxNy films has been studied. The films have been deposited from mixtures of SiH4, O2 and N2, using the electron cyclotron resonance–chemical vapor deposition technique, with substrate temperature ranging from room temperature (50 °C) to 200 °C. When substrate temperature is increased, a slight decrease in both Si–H and N–H bond concentration is detected. A small shift (10–17 cm-1) in the dominant Fourier transform infrared (FTIR) absorption peak (Si–O/Si–N stretching band) seems to be associated with a decrease in the N–H bond concentration. This behavior is attributed to the formation of Si–N bonds at the expense of N–H bonds, with no significant change in the film composition. Full width at half maximum (FWHM) of the dominant FTIR peak decreases as temperature is increased for all the composition range, indicating an improvement in the quality of the films. Silicon oxide films (SiO2.0) deposited at 200 °C show improved properties with respect to those deposited at room temperature. FWHM decreases from 95 to 87 cm-1, and the shoulder-to-peak ratio from 0.29 to 0.22. The position of the Si-O stretching band (1071 cm-1) is unaffected. These values are very close to those obtained for thermally grown oxides, while the thermal budget of the process is significantly reduced. © 1999 American Vacuum Society.