Deposition of optical thin films by ion beam sputtering

Abstract

The use of sputtering from diode or magnetron sources has been investigated thoroughly in the last few years in order to replace traditional evaporation methods for optical thin film deposition. The kinetic energy of sputtered materials, higher than that of evaporated atoms, is one of the most important causes of the superior adherence, hardness and mechanical stability of sputtered thin films. Present technology evolution is tending to develop new techniques, allowing higher and more controllable energies of materials impinging on the substrate. In the ion beam sputter deposition (IBSD) technique the working pressure in the deposition chamber may be lower than 10 -2 Pa, so thermalization of sputtered materials is avoided and the energies of depositing atoms are higher than in plasma sputtering, where thermalization takes place. This work describes the investigations carried out for realizing optical treatments by means of IBSD. The apparatus used for this study is described with details of the experiments carried out and the results obtained in the deposition of TiO 2, Y 2O 3, Al 2O 3, SiO 2 and ZnS. The films are characterized optically, mechanically and for the determination of the damage threshold from 1064 nm laser radiation.