Silicon oxynitride (OXN) gate dielectric thin films have been prepared in a cluster tool using a low thermal-budget process combining plasma and rapid-thermal step. This N-2-based process has (i) increased process latitude for the formation of N-rich alloys, and (ii) resulted in lower bonded-H concentrations, in comparison to NH3-based processes. On-line Auger electron spectroscopy and off-line infrared spectroscopy have been used to characterize chemical bonding, showing that the deposited films are pseudobinary alloys, (SiO2)(x)(Si3N4)(1-x). The processing steps are (i) a 300 degrees C plasma-assisted oxidation, (ii) a 300 degrees C plasma-assisted chemical vapor deposition of oxynitride films, and (iii) a 30 s, 900 degrees C postdeposition rapid-thermal anneal. Electrical characterization of O-OXN-O structures in metal-oxide-semiconductor capacitors was performed using capacitance-voltage techniques to evaluate the effect of alloy composition on midgap interface state density, D-it, and flat-band voltage, V-fb.