Conversion of a plasma enhanced chemical vapor deposited silicon-carbon-nitride thin film at ultra-low temperature by oxygen plasma

In this work we present an ultra-low temperature method for the oxidation of an amorphous silicon-carbide-nitride (SiCN) material. The SiCN is deposited on silicon substrates by plasma enhanced chemical vapor deposition using CH₄, SiH₄, and N₂ chemistry. The physical and chemical properties are characterized for the as-deposited SiCN and post-oxidized films are discussed. The SiCN film is exposed to oxygen plasma, where it undergoes a chemical transformation into a binary SiO₂ material system. A 1.7 nm/min oxidation rate is typical for this process and compares favorably to oxidation methods utilizing much higher temperatures. The substrate temperature remains extremely low throughout the oxidation process, T_s < 200 °C. Changes in film stress, optical constants, film thickness, surface roughness, and film density are measured. Chemical analysis by X-ray photoelectron spectroscopy is reported for both the as-deposited and oxidized film and confirms the resultant film to be the chemical equivalent of thermally grown SiO₂. We discuss applications specifically targeted to the conversion of SiCN to SiO₂.