Stress Control and Ferroelectric Properties of Lead Zirconate Titanate (PZT) Thin Film on Si Substrate with Buffer Layers

Abstract

Lead zirconate titanate (PZT) thin films were grown on a Si substrate with an epitaxial relationship by introducing yttria-stabilized zirconia (YSZ), CeO2, and (La,Sr)CoO3 (LSCO) buffer layers. The buffer layers, which facilitated the growth of the epitaxial PZT thin film and controlled the residual stress, were deposited by pulsed laser deposition (PLD). The PZT thin films were fabricated on [A]: LSCO*/CeO2/YSZ/Si and [B]: LSCO*/PZT*/LSCO/CeO2/YSZ/Si by pulsed metalorganic chemical vapor deposition. The respective thicknesses of the LSCO* and PZT* layers were changed to control the residual stress in the PZT thin films. The relationship between residual stress and the ferroelectric properties of the PZT thin films was investigated. Residual tensile stresses in the PZT thin films were maximum in [A] as LSCO* thickness changed. Increasing the PZT* layer thickness at a fixed thickness of LSCO* of 188 nm changed the residual tensile stress in the PZT thin films from 2.92 GPa to 2.67 GPa. Consequently, remanent polarization (2Pr) was increased from 15 µC/cm2 to 27 µC/cm2, suggesting that residual stress may be controlled by introducing buffer layers and that ferroelectric properties may be improved.