Microstructure and properties of rf-sputtered amorphous hydrogenated silicon films

Abstract

The effect of both total gas pressure (Ar+H2) and partial pressure of H2 during the rf-sputtering of amorphous hydrogenated silicon films was investigated. It is shown that decreasing the total gas pressure (PT) leads to a number of consistent and desirable film characteristics including no post-deposition oxidation, essentially zero etch rate, no resolvable microstructure, predominant monohydride bonding, and low optical band gap. These lowest PT films contain ∼17 at. % H and 4 at. % Ar, have reasonable deposition rates (60–70 Å/min) and are in a high state of compressive stress. The relations between the deposition variables and the more fundamental surface reaction processes are discussed. Specifically, we demonstrate that Ar ion bombardment effects, due to high negative substrate self-biases, are dominant at low PT.