Deposition of Pb(Zr,Ti)O3 Thin Films by Metal‐Organic Chemical Vapor Deposition Using β‐diketonate Precursors at Low Temperatures

Abstract

Lead zirconate titanate (PZT) thin films were deposited by metal‐organic chemical vapor deposition (MOCVD) using β‐diketonate precursors and 02 at temperatures below 500°C on variously passivated Si substrates. PZT thin films could not be deposited on bare Si substrates, owing to a serious diffusion of Pb into the Si substrate during deposition. Pt/SiO2/Si substrates could partially block the diffusion of Pb, but a direct deposition of PZT thin films on the Pt/SiO2/Si substrates resulted in a very inhomogeneous deposition. A TiO2 buffer layer deposited on Pt/SiO2/Si substrates could partially suppress the diffusion of Pb and produce homogeneous thin films. However, the crystallinity of PZT thin films deposited on the TiO2‐buffered Pt/SiO2/Si substrate was not good enough, and the films showed random growth direction. PZT thin films deposited on the PbTiO3‐buffered Pt/SiO2/Si substrates had good crystallinity and a‐ and c‐axis oriented growth direction. However, the PZT thin film deposited at 350°C showed fine amorphous phases at the grain boundaries, owing to the low chemical reactivities of the constituent elements at that temperature, but they could be crystallized by rapid thermal anneaiing (RTA) at 700°C. PZT thin film deposited on a 1000‐å PbTiO3,‐thin‐film‐buffered Pt/SiO2/Si substrate at 350°C and rapid thermally annealed at 700°C for 6 min showed a single‐phase perovskite structure with a composition near the morphotropic boundary composition.