The chemical kinetics and process–property relationships of silicon oxynitride films grown in nitrous oxide ambients were investigated. Gas phase compositions in the furnace were experimentally determined with mass spectrometry and were found to be within ±5&percent; of the ones calculated theoretically. Experimental observations in the furnace suggested that the reaction between NO and oxygen to formNO2inside the furnace was negligible. Silicon oxynitride films were grown at 950 °C and atmospheric pressure for times ranging between 30 min and 24 h. Ellipsometry was used to measure the film thickness. The observed thin-film growth was parabolic with time and appeared to saturate after about 24 h, that is, significantly slower than the oxynitride growth by rapid thermal processing. Secondary ion mass spectrometry (SIMS) used in the depth profiling of oxynitrides showed a sharp accumulation of nitrogen at the oxynitride–silicon interface. Additional experimental data suggested that nitric oxide is the species responsible for nitrogen incorporation at the interface and removal of nitrogen from the bulk film. Mass spectrometric, ellipsometric, and SIMS analyses of furnace silicon oxynitridation in nitrous oxide ambients were used for the development of a model of the process. Model predictions are in agreement with all trends of the experimental data obtained. ©1997 American Institute of Physics.