Influences of Annealing on Residual Stress and Structure of HfO₂ Films

HfO₂ films are deposited on BK7 glass substrates by electron beam evaporation. The influences of annealing between 100°C and 400°C on residual stresses and structures of HfO₂ films are studied. It is found that little differences of spectra, residual stresses and structures are obtained after annealing at lower temperatures. After annealing at higher temperatures, the spectra shift to short wavelength, the residual stress increases with the increasing annealing temperature. At the same time, the crystallite size increases and interplanar distance decreases. The variations of optical spectra and residual stress correspond to the evolutions of structures induced by annealing.