Temperature-dependent hillocks and cracks on the piezoelectric thin film lead-zirconate-titanate were studies. The thin film was deposited onto Pt/Ti/SiO2/Si substrate by metal organic decomposition where Pt was a bottom electrode and Ti was an adhesive layer. Experimental results demonstrated that, if the annealing temperature exceeded 700C, Ti diffused into the Pt layer, and Pt recrystallized. In addition, partially volatilizable solution in PZT evaporated and thus, caused volume change and residual stresses. Hillocks and cracks in PZT were primarily caused by the above-mentioned thermal effects and made the top electrode and the bottom electrode electrically short. Two methods were applied to improve the thermal effects of Pt and Ti. PZT thin film with perovskite structure was well characterized by X-ray diffractometer and a hysteresis loop. The remnant polarization was 20.448μC/cm2, and the coercive field was 183.299V/cm. The resonant and anti-resonant frequencies were 14.95 and 20.2kHz, respectively. The piezoelectric constants, d31 and d33, and the electromechanical coupling coefficient were 159.57pC/N, −72.86pC/N and 0.672, respectively.

Thermal Effects in PZT - Diffusion of Titanium and Recrystallization of Platinum. C.L.Dai, F.Y.Xiao, C.Y.Lee, Y.C.Cheng, P.Z.Chang, S.H.Chang: Materials Science and Engineering A, 2004, 384[1-2], 57-63