Properties of SiOxNy films deposited by LPCVD from SiH4/N2O/NH3 gaseous mixture

Varied silicon oxynitride SiOxNy films are grown by low pressure chemical v apour deposition (LPCVD) from silane SiH4, nitrous oxide N2O and ammonia NH 3 by adjusting the N2O/NH3 gas flow ratio. Film thicknesses and refractive indexes are measured by ellipsometry and profilometry, The SiOxNy stoichiom etries are characterized by X-ray photoelectron spectroscopy (XPS) and the results are compared to the Bruggeman theory applied to the SiO2/Si3N4 hete rogeneous medium. Film residual stresses are finally characterized by profi lometry through wafer curvature measurements. From compressive to tensile s tress values are obtained, evidencing the existence of a no-stress oxynitri de film. Such phenomena are related to the SiOxNy stoichiometry and explain ed by considering the deposition mechanisms of the SiH4/N2O/NH3 gaseous mix ture and the thermo-mechanical properties of silicon oxynitride. (C) 1999 E lsevier Science S.A. All rights reserved.