Liquid Injection Atomic Layer Deposition of Pb(Zr,Ti)O3 Thin Films on Three Dimensional Structures

A liquid injection atomic layer deposition (ALD) process has been developed for conformal deposition of lead zirconate titanate thin films on three dimensional structured silicon substrates. Future applications of these structures address the field of nonvolatile ferroelectric memory devices. PZT films were prepared by mixing the binary ALD processes of PbO_x, TiO_x, and ZrO_x. It was found that the type of precursors as well as the stacking sequence of the binary oxide layers is crucial for the control of film stoichiometry and for a saturation of the film growth behaviour characteristic for ALD processes. Using an optimized ALD process the molar ratios of Pb/(Ti+Zr) as well as Zr/(Ti+Zr) in the films show a saturation behaviour against an increasing precursor injection volume. Pb(Zr_xTi_1-x)O₃ films deposited on 3D structured silicon exhibited a uniform film thickness and a homogeneous cation composition over the complex structure.