Growth Behavior of Atomic-Layer-Deposited Pb ( Zr , Ti ) Ox Thin Films on Planar Substrate and Three-Dimensional Hole Structures

Abstract

Quaternary (PZT) films were deposited at by a combination of liquid-injection atomic layer deposition (ALD) of binary PbO, , and thin films. In preliminary work, binary films were deposited at by ALD. Two solutions of and dissolved in ethylcyclohexane (ECH) were prepared, and it was found that the solution provides a three-times-higher deposition rate for the films than the solution. We focused the study on the set of precursors which offers the highest degree of flexibility for adjusting the ratio in the PZT films: , , and dissolved in ECH, and water as the oxidant. This set of solutions contributed to increasing the ratio in the deposited PZT films to more than 0.2, which remained below 0.1 in the ALD-PZT using , , and . The ratio was further increased to 0.5 by modifying the sequence of the discrete-source gas pulses. A polarization–voltage hysteresis loop was observed for a thick PZT film deposited on a planar substrate after postannealing for crystallization. To assess the feasibility of ALD as a tool for coating three-dimensional (3D) structures uniformly, PZT films were deposited on submicrometer 3D structures. As-deposited amorphous PZT films as well as crystallized PZT films were both free of any gradient in the cation composition over the structure. The present work reports interesting interactions on stacking different binary-oxide layers by ALD and demonstrates why the multiprecursor ALD process is a promising approach for uniformly coating 3D nanostructures with complex oxide materials.