Effects of ion energy on internal stress and optical properties of ion-beam sputtering Ta2O5 films

Abstract

The effects of ion-beam energy on the internal stress and optical properties of tantalum pentoxide (Ta2O5) thin film have been investigated. Ta2O5 thin films were deposited on unheated glass substrates by ion-beam sputter deposition (IBSD) with different ion-beam voltage V b. The mechanical properties, internal stress and surface roughness, and the optical properties, refractive index and absorption, were studied directly after deposition. The refractive index, extinction coefficient and surface roughness were found to depend on the ion-beam energy. The internal stresses were measured by the phase-shifting interferometry technique. The film stress was also found to be related to V b, and a high compressive stress of -0.560 GPa was measured at V b = 750 V. Ta2O5/SiO2 multilayer coatings had smaller average compressive stress than single-layer Ta2O5 film.