O3-TEOS CVD Film Formation on Thermal SiO2 Pre-Coated with Ethanol

Abstract

We previously reported that organic solvent (ethanol) treatment of a film formed by plasma enhanced chemical vapor deposition (PE-CVD) remarkably improved the gap-filling property of O3-tetraethylorthosilicate (O3-TEOS) atmospheric pressure chemical vapor deposition (AP-CVD) film. Based on these results, we concluded that alkoxy (ethoxy) groups, which are generated by ethanol treatment, reduced the adsorptive activities of the sites distributed on the surface, causing a decrease in the sticking probability of vapor-phase species responsible for the deposition. However, an opposite hypothesis has been reported, which proposes that ethoxy groups become adsorption sites. In this study, we offer a counterargument and clarify that ethoxy groups, which were generated by ethanol treatment following light etching using dilute hydrofluoric acid (HF), do not become adsorption sites on the surface of thermally grown silicon dioxide (thermal SiO2) during O3-TEOS film deposition, since the O3-TEOS film was formed at a low deposition rate (DR). A smooth surface and excellent gap-filling into the patterns covered with thermal SiO2 were observed on the O3-TEOS film formation by ethanol treatment. We propose that a degasification step during O3-TEOS film formation or during annealing after the deposition could be closely related to improved surface roughness and gap-filling.