The mechanical properties and microstructure of plasma enhanced chemical vapor deposited silicon nitride thin films

Abstract

Plasma enhanced chemical vapor deposited silicon nitride thin films, possessing a wide range of mechanical and physical properties, were made by changing the flow rate ratios of the various processing gases, NH3/SiH4/N2, while basically keeping the other deposition parameters constant. A set of films with N/Si ratios of 1.0 to 1.5 were produced, all showing compressive stress. The intrinsic compressive stress was found to increase with increasing amounts of N–H bonding. The density and Young’s modulus also increased with increasing amounts of N–H bonding. The values for Young’s modulus, obtained by using a Nano indenter instrument, were mainly dependent upon the film density, and the hardness to modulus ratio was 0.09 for all of the silicon nitride thin films.