Minimizing hydrogen content in silicon oxynitride by thermal oxidation of silicon-rich silicon nitride
Abstract This work reports a detailed study of the re-oxidation effects on the hydrogen content and optical properties of silicon oxynitride films grown by plasma enhanced chemical vapor deposition (PECVD) with N 2 O, NH 3 and SiH 4 as the precursors. Results showed that the silicon oxynitride deposited with gas flow rates of NH 3 /N 2 O/SiH 4  = 20/500/20 (sccm) has favorable properties for integrated waveguide applications. The refractive index of this layer is about 1.57 at 632.8 nm wavelength and the layer has a comparative low density of N H bonds. With a high temperature re-oxidation of the as-deposited film, the hydrogen content of the oxynitride film was reduced from 2.255 × 10 22 to 6.98 × 10 20  cm −3 which is attributed to the removal of excess silicon oxidation and hydrogen bonds.