Preparation and characterization of plasma enhanced chemical vapor deposited silicon nitride and oxynitride films

Abstract

A brief description of the plasma enhanced chemical vapor deposited unit is first presented as well as typical processing conditions used in the elaboration of silicon nitride and silicon oxynitride layers with refractive indices of 1.96 and 1.78, respectively, and with thicknesses superior to 30 nm. The compositional characterization of as-deposited films (prepared at 380 °C) has been carried out with infrared and Auger spectroscopies indicating a composition near the stoichiometry for nitride films (Si/N=0.8), a concentration of 16% of oxygen for oxynitride films, and a small amount of hydrogen. Extensive electrical measurements were made using I–V and C–V techniques as well as deep-level transient spectroscopy on metal-insulator semiconductor structures. Films with resistivities of 5×1016 Ω cm at a field of 2 MV/cm were obtained. The static dielectric constant is around 7 and 5.5 for nitride and oxynitride films, respectively. Finally C–V data indicate an interface state density lower than 3×1011 cm−2 eV−1 at the midgap and a positive fixed charge lower than 1012 cm−2.