The effects of substrate temperature and lead precursor flow rate on the fabrication of (Pb,La)(Zr,Ti)O-3 thin films by electron cyclotron resonance plasma-enhanced chemical vapor deposition

Abstract

La-doped lead zirconate titanate (PLZT) thin films were fabricated on Pt/Ti/SiO2/Si substrates by electron cyclotron resonance plasma-enhanced chemical vapor deposition (ECR-PECVD) method. The composition and the electrical properties of the films were investigated as a function of deposition temperature and Pb-source flow rate. Stoichiometric film with pure perovskite structure was fabricated at a deposition temperature as low as 450 degrees C. As the deposition temperature was increased, the vapor pressure of lead oxide molecules increased and thus the PLZT film tended to be Pb-deficient, resulting in the formation of a non-perovskite phase and the degradation of electrical properties. This problem could be relieved by increasing the Pb-source flow rate. Rapid thermal annealing (RTA) greatly enhanced the electrical properties of the PLZT film as long as the as-deposited film had stoichiometric composition and pure perovskite structure. The rapid thermal annealed PLZT film (74 nm thick) had an effective charge density of 150 fF/mu m(2), dielectric constant of 1216 and SiO2 equivalent thickness of 0.24 nm.