Investigation of the Composition of Sputtered Silicone Nitride Films by Nuclear Microanalysis

Abstract
The composition and uniformity of silicon nitridethin filmsdeposited by reactive sputtering in a mixture of argon and nitrogen eventually contaminated by oxygen traces were studied. Both direct observation of nuclear reactions on nitrogen and oxygen and backscattering of 4He+ions were used to analyze the deposits. The films appear uniform as a function of depth. They are practically oxygen free but contain large amounts of argon. Their stoichiometry changes with the partial pressure P N2 of nitrogen. The ratios N/Si and Ar/Si vary in the opposite direction; for smaller values of P N2 there is an excess of silicon, whereas for larger values an excess of nitrogen is observed with respect to the stoichiometric composition Si3N4.