Intrinsic stress dependence of c-axis orientation ratio in PbTiO3 thin films deposited by reactive sputtering

Abstract

Highly c-axis oriented lead titanate (PbTiO3) thin film, having a perovskite structure, was prepared on magnesium oxide (MgO) (100) single crystal using multiple cathode dc-magnetron sputtering at 600 degrees C. The film was annealed at 700 degrees C for up to 8 h. Both the c-axis orientation ratio P and c-axis lattice parameter of the film decreased with the increase of the annealing time. It was confirmed that the decrease of the c-axis lattice parameter with the annealing time was due to the relaxation of the intrinsic stress generated during deposition. These experimental results suggested that P was related to the intrinsic stress. The film deposited at various working pressures was examined in detail to confirm the intrinsic stress effect of P. P of 95% at 8 mTorr decreased to 60% at 70 mTorr. The pressure dependence of P was explained by the intrinsic stress change. Regardless of the sputtering condition, all P's were reduced to 40% after annealing at 700 degrees C for 8 h. The difference in P between the before and after annealing was caused by the relaxation of the intrinsic stress. It was supposed that the remaining 40% of P after the heat treatment was caused, in the most part, by the ferroelectric phase transition. (C) 1997 American Vacuum Society.