Stress and Density of Thin TiO2 Films Produced by Different Methods

Abstract

AbstractStress, density and refractive behavior are analyzed for TiO2 layers deposited by reactive evaporation (RE), ion plating (IP), plasma impulse chemical vapour deposition (PICVD) and spin coating (SP) from bending of the substrate and by means of Rutherford Backscattering Spectroscopy (RBS), respectively. Densities between 2.7 gem-3 and 3.8 gem-3 are obtained depending on coating techniques and coating conditions. Refractive index depends linear on density. A correlation between film stress and density is observed which is independent from coating process, production parameters and crystal structure of the as-deposited films. Stress is tensile at low densities and compressive for films with densities of the order of the crystal phase of anatase (3.84 gem-3). The phase transition from amorphous to anatase due to annealing induces an increase in stress. Film density determines the transition temperature, and the magnitude of stress increase.