Textured strontium titanate layers on platinum by atomic layer deposition

Abstract

Formation of textured strontium titanate (STO) layers with large lateral grain size (0.2–1μm) and low X-ray reflectivity roughness (~1.36nm) on Pt electrodes by industry proven atomic layer deposition (ALD) method is demonstrated. Sr(t-Bu3Cp)2, Ti(OMe)4 and O3 precursors at 250°C were used to deposit Sr rich STO on Pt/Ti/SiO2/Si ∅200mm substrates. After crystallization post deposition annealing at 600°C in air, most of the STO grains showed a preferential orientation of the {001} plane parallel to the substrate surface, although other orientations were also present. Cross sectional and plan view transmission electron microscopy and electron diffraction analysis revealed more than an order of magnitude larger lateral grain sizes for the STO compared to the underlying multicrystalline {111} oriented platinum electrode. The combination of platinum bottom electrodes with ALD STO(O3) shows a promising path towards the formation of single oriented STO film.