Effect of low temperature oxidation on dielectric properties of mercury sensitized photo-deposited silicon nitride films

Low temperature thermal oxidation of mercury-sensitized photo-CVD deposited silicon-rich silicon nitride films has been carried out to obtain high quality silicon oxynitride films with less incorporated hydrogen. The absence of SiH and NH stretching mode indicates that the incorporated hydrogen in these bonding forms is a few atomic percent, below the detection level of Fourier transform infrared spectroscopy (FTIR). X-ray photoelectron (XPS) studies suggest that oxygen is mainly incorporated in the film in the form of N(SiO)x. No significant change in the relative contributions from the Si3N4 network to the overall N 1s peak takes place as a result of oxidation, but there is a decrease in the unreacted silicon from 15.3% to 5.5%. The interface electronic state densities, flat band voltage, fixed insulating charges and leakage current are reduced after oxidation, indicating an improvement of the electrical properties of the oxidized film.