Growth of thin film ferroelectric PZT, PHT, and antiferroelectric PHO from atomic layer deposition precursors

Abstract

Abstract We present a conformal method of growing ferroelectric lead hafnate‐titanate (PbHf x Ti 1− x O 3 , PHT) and lead zirconate‐titanate (PbZr x Ti 1− x O 3 , PZT) using atomic layer deposition (ALD) precursors. The 4+ cation precursors consist of tetrakis dimethylamino titanium (TDMAT), tetrakis dimethylamino zirconium (TDMAZ) and tetrakis dimethyl amino hafnium (TDMAH) for Ti, Zr, and Hf, respectively. The Pb (2+) precursor was Lead bis(3‐N,N‐dimethyl‐2‐methyl‐2‐propanoxide) [Pb(DMAMP) 2 ]. PZT was limited to lead titanate (PTO)‐rich compositions, where x <0.25 for PbZr x Ti 1− x O 3 , and exhibited a remnant polarization of 26‐27 µC/cm 2 with a coercive field between 150 and 170 kV/cm. The 3D‐structure coating capability of PZT was demonstrated by deposition on micromachined trench sidewalls 45 µm deep. We fabricated Microelectromechanical systems (MEMS) cantilever arrays with PZT thin films grown using the present method and demonstrated piezoelectric actuation. Alternatively, PHT was deposited with Ti and Hf compositions within ±1 at.% of the morphotropic phase boundary (MPB). The PHT exhibited a remanent polarization of 7.0‐8.7 µC/cm 2 with a coercive field between 84‐100 kV/cm. We applied the same Pb and Hf precursors from the PHT process to grow antiferroelectric lead‐hafnate (PHO), which showed the characteristic electric field‐induced ferroelectric phase transition at approximately ±280 kV/cm and a maximum polarization of approximately ±32.8 µC/cm 2 .