Novel chemistry for high-quality, low-hydrogen PECVD silicon nitride films.

We have developed a low temperature ~ 300C) plasma deposition process to prepare novel fluorine-containing silicon nitride films (p-SiN:F) using SiH sub 4-NF sub 3-N sub 2 discharge mixtures at 14 MHz RF applied frequency. The deposition rate can be extremely high, up to 1600 angstroms/min. Preliminary data indicate p-SiN:F has electrical properties (dielectric constant, breakdown strength), resistivity, etc.) which compare favorably with high temperature CVD silicon nitride. By controlling the feed chemistry and physical variables of the discharge, a wide variety of film compositions are achieved. Moreover, our chemistry is superior to the only other p-SiN:F which was prepared from a SiF sub 2/SiF sub 4-H sub 2-N sub 2 feed. Two classes of films were identified as stable or unstable to air exposure and the instability of the films correlated with the atom fraction of fluorine initially incorporated.