Liquid Injection ALD of Pb(Zr,Ti)O[sub x] Thin Films by a Combination of Self-Regulating Component Oxide Processes

Abstract

Quaternary Pb (Zr,Ti) Ox [PZT] films were deposited at 240°C by a combination of liquid injection atomic layer depositions (ALD) of binary PbO, Ti Ox, and Zr Ox thin films. We used water as the oxidant and two sets of precursors: Pb (C11 H19 O2) 2 [Pb (DPM)2], Zr (C11 H19 O2) 4 [Zr (DPM)4], and either Ti (O C3 H7) 2 (C11 H19 O2) 2 [Ti (Oi-Pr)2 (DPM)2] or (TiO C3 H7) 4 [Ti (Oi-Pr)4]. These precursors were dissolved in ethylcyclohexane and separately injected into a vaporizer. The deposition rates of the metal elements were investigated as a function of the input of the solutions. We started the ALD-PZT process with Ti (Oi-Pr)2 (DPM)2. When the input of one solution was increased, the deposition rates of the metal elements continued to increase or fluctuate, showing a complex interdependence. A PZT film deposited on a three-dimensional (3D) structure had an inhomogeneous cation composition. The film uniformity on the 3D structure was significantly improved by substituting Ti (Oi-Pr)2 (DPM)2 with Ti (Oi-Pr)4. In this ALD-PZT process, self-regulated growths were confirmed for Pb and Zr. Although the deposition rate of Ti did not saturate due to a catalytic decomposition, this study suggests that the multilayer stacking ALD process is an effective method for building up homogeneous layers of multicomponent materials on desired 3D structures. © 2007 The Electrochemical Society.