Full composition range silicon oxynitride films deposited by ECR-PECVD at room temperature

Abstract

Silicon oxynitride films were deposited at room temperature using the ECR-PECVD technique. Precursor gases were O(2), N(2) and SiH(4). The composition of the films can be controlled by regulating the gases flow ratio. R = (O(2) + N(2))/SiH(4) and R' = O(2)/SiH(4) have proved to be the key deposition parameters. FTIR spectroscopy, AES and ellipsometric measurements were performed in order to characterise the films. A single Si-O/Si-N stretching band is observed in the FTIR spectrum for all compositions, indicating single-phase homogeneous SiO(x)N(y) films. FWHM of the stretching band shows a maximum for the composition corresponding to the same number of Si-O and Si-N bonds. Samples cover the whole composition range from silicon nitride to silicon oxide including nitrogen-rich films, even though the gas flow ratio R " = N(2)/O(2) during deposition was small (from R " = 1.0 for SiO(1.9)N(0.04) to R " I = 6.7 for SiO(0.26)N(1.2)). Silicon oxide composition samples (SiO(2.0)) show essentially the same TR features as the thermal oxide: Si-O stretching band located at 1072 cm(-1), with a FWHM of 96 cm(-1) and a shoulder/peak ratio of 0.30, while nitrogen-rich samples (SiO(0.26)N(1.2)) show a total bonded hydrogen content below 2 x 10(22) cm(-3).