Mechanical stress in thin SiO 2 and Ta 2O 5 films produced by reactive-low-voltage-ion-plating (RLVIP)

Abstract

SiO 2 and Ta 2O 5 films on unheated glass substrates deposited by reactive low voltage ion plating (RLVIP) have high compressive stresses of more than 1.2 GPa for film thicknesses < 100 nm. With increasing film thickness to 700 nm the stresses decrease exponentially to 0.7 GPa for SiO 2 and 0.55 GPa for Ta 2O 5. Increasing the ion current density to 0.45 mA cm −2 during film deposition while maintaining (gas pressure and gas composition) increases the number (ion—molecule-reactions in the plasma) of energetic particles, increase the film density but also the compressive film stress. However, while maintaining stoichiometry parameter sets could be found for dense and therefore stable films with acceptable low compressive stress.