Deposition of Dense SiO2 Thin Films for Electrical Insulation Applications by Microwave ECR Plasma Source Enhanced RF Reactive Magnetron Sputtering

Silicon dioxide thin films have been deposited successfully on high speed steel (HSS) cutting tool substrates by means of microwave electron cyclotron resonance (MW-ECR) plasma source enhanced RF reactive magnetron sputtering of a pure silica target in an oxygen and argon mixture. The films are characterized by atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FT-IR). Chemical composition of the thin films on HSS cutting tools have been investigated as a function of the gas volume ratio [O₂]/[Ar], RF power and substrate bias. A comparative study of the SiO₂ thin films deposited at -20V DC bias and -80V RF bias is presented. An improvement of the SiO₂ thin film properties due to increased energetic substrate bombardment has been found. It is concluded that SiO₂ thin films deposited on HSS cutting tools by this method are compact and dense, and have good stoichiometry and electrical insulation properties.