DEPOSITION OF SIO2 AND TA2O5 FILMS BY ELECTRON-BEAM-EXCITED PLASMA ION PLATING

Refractory metal-oxide coatings are widely used for optical interferen ce applications. Conventional evaporation films have inferior optical and structural properties compared with the bulk form. These films oft en have a columnar microstructure with voids which leads to the instab ility of the optical properties (e.g., the spectral characteristics). Hence, electron-beam-excited plasma (EBEP) ion plating has been develo ped. The process, operated by injecting a low-energy ( similar to 150 eV) high-current ( similar to 30 A) electron beam into a vacuum chambe r, produces high-density plasma at low pressure. SiO2 and Ta2O5 films for optical applications were deposited by the process. Films prepared at an oxygen pressure of 1-2 X 10(-4) Torr showed good stoichiometry and dense microstructure, which lead to the absence of significant spe ctral shifts resulting from changes in the temperature and the humidit y of the ambient atmosphere. The above results prove that this process is a promising tool for the large-area deposition of refractory metal -oxides at low temperatures.