PROCESSING OF PBTIO3 THIN-FILMS .2. IN-SITU INVESTIGATION OF STRESS-RELAXATION

Stress relaxation in PbTiO3 films was investigated by the in situ stre ss measurement technique. A simple viscous flow model was successfully used to interpret the kinetics and behavior of stress relaxation of P bTiO3 thin films. The activation energy responsible for stress relaxat ion was estimated to be 190 kJ/mole, which was accounted for by the la ttice diffusion of vacancies. A Nabarro-Herring creep model was succes sfully employed to correlate the relationships among the viscosity, la ttice diffusion coefficient, and grain size of the PbTiO3 films, and a n estimate of the lattice diffusion coefficient of vacancy motion duri ng relaxation was obtained. Also, the observed time required for compl ete relaxation was found to be in accord with theoretical values. Hill ock formation resulting from grain boundary sliding is believed to con tribute to stress relaxation in its early stage. Thereafter, grain gro wth resulting from lattice diffusion is believed to play a major role in the stress relaxation. (C) 1996 American Vacuum Society.