Effects of O-2- and N2O-plasma treatments on properties of plasma-enhanced-chemical-vapor-deposition tetraethylorthosilicate oxide

Abstract

The high quality silicon oxide films were prepared by plasma-enhanced chemical vapor deposition (PECVD) using tetraethylorthosilicate (TEOS)-oxygen based chemistry. The O-2- or N2O-plasma treatments were performed on the as-deposited films as an attempt to improve the properties of the TEOS oxide films. TEOS oxide film deposited at lower pressure had lower Si-OH content, less carbon impurity, and flatter surface, and hence had better electrical properties. Both O-2- and N2O-plasma would decrease the oxygen content of the oxide film, which led the composition of the film to deviate from the stoichiometric SiO2. The O-2-plasma treatment did not show the encouraging effect on the chemical structure and electrical properties of the TEOS oxide films. In contrast, the N2O-plasma treatment could be a promising means to improve the breakdown field and leakage current density of the TEOS oxide films, which was accomplished by the N2O-plasma effect to facilitate the passivation of dangling bonds, linking reaction of Si-OH bonds, nitridation reaction and densification of the amorphous silicon oxide network.