Integrated processing of silicon oxynitride films by combined plasma and rapid-thermal processing

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 N2-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 °C plasma-assisted oxidation, (ii) a 300 °C plasma-assisted chemical vapor deposition of oxynitride films, and (iii) a 30 s, 900 °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, Dit, and flat-band voltage, Vfb.