In this work we present the results of studies on the deposition and characterization of silicon oxynitride films deposited by plasma enhanced chemical vapor deposition technique using N2, N2O and SiH4 gaseous mixtures at low temperatures. Rutherford backscattering spectroscopy and refractive index measurements demonstrate that it is possible to transit from silicon dioxide to stoichiometric silicon nitride by varying the N2/N2O ratio in the precursor gaseous mixture. Stress measurements and plasma etching experiments show that both the internal stress and the etching rate are very sensitive to the films chemical composition and for specific deposition conditions it is possible to obtain films with very low stress and with high plasma etching rate. These results are very promising for application in low-cost, compact integrated optical devices. © 2004 Elsevier B.V. All rights reserved.