Metallorganic chemical vapor deposition of Pb(Zr, Ti)O-3 films using a single mixture of metallorganic precursors

Abstract

Pb(tmhd)(2), Ti(O'Pr)(2)(tmhd)(2), and Zr-2(O'Pr)(6)(tmhd)(2) were used as metallorganic chemical vapor deposition (MOCVD) sources for Pb(Zr, Ti)O-3 (PZT) films. Thermal properties of PZT precursors and the stability of precursor solution were evaluated. A mixed solution of three precursors in tetrahydrofuran (THF) solvent showed a time-dependent degradation due to a ligand exchange reaction between Pb(tmhd)(2) and Zr-2(O'Pr)(6)(tmhd)(2). Growth characteristics of PZT thin films deposited on a (111)Pt/TiO2/SiO2/Si substrate by MOCVD have been investigated. A direct liquid injection technique using a flash-vaporized metallorganic precursor solution was employed for the film deposition. The incorporation rates of constituent metals in the PZT film are strongly dependent on the substrate temperature and precursor molar ratios in the precursor solution. As the substrate temperature was increased, the incorporation rate of Ph and Ti increased and that of Zr remained constant. As the ratio of Zr/Ti in the PZT precursor solution was increased, Pb/(Zr + Ti) decreased and Zr/(Zr + Ti) increased. Pure perovskite films were obtained at temperatures between 470 and 530 degreesC when a solution with an atomic ratio of Pb:Zr:Ti = 1.1:0.4:0.6 was used. (C) 2001 The Electrochemical Society.