Hydrogen incorporation in dual-mode PECVD amorphous silicon oxide thin films

Hydrogen incorporation in amorphous silicon oxide thin films a-SiOx:H (0.5 < x < 2.0) was studied quantitatively by combining nuclear analysis (Rutherford backscattering spectrometry (RBS) and elastic recoil detection analysis (ERDA)) and IR absorption spectroscopy. The films were obtained at low temperatures (40-250 degrees C) and high growth rates (R(d)) up to 55 Angstrom s(-1) using a dual-plasma-enhanced chemical vapour deposition (dual-PECVD) reactor. Hydrogen atoms were bonded to Si in Si-rich films, whereas in nearly stoichiometric films H atoms were only bonded to oxygen in Si-OH and H2O configurations. The intensity of the OH broad absorption band increased for films produced at low temperatures and high oxygen flow rates (high deposition rates). No modification of the spectrum was observed after thermal annealing at 250 degrees C, even for thin films deposited at 70 degrees C, indicating good stability of the bonded H. Quantitative analysis of the stoichiometry of the films was undertaken, and the proportionality constants between the atomic concentration and the integrated absorbance for Si-O-Si, Si-O-H and H-O-H stretching modes and the H-O-H bending mode are given.