Optimized Electrical Properties and Chemical Structures of SrTiO3 Thin Films on Si Using Various Interfacial Barrier Layers

Abstract

Interfacial barrier layers (IBLs), such as a thermally grown SiO2 using O-3, thermally nitrided SiOxNy using NH3, and an atomic layer deposited (ALD) HfO2 layer, were used as an interface layer between a sputtered SrTiO3 film and a Si substrate. Sr-silicate phase formation at the interface between the SrTiO3 film and Si substrate was suppressed by these IBLs. The ALD HfO2 layer was the most effective diffusion/reaction barrier against Si diffusion and the interfacial reactions among the IBLs examined. However, the crystallinity of the SrTiO3 layer deteriorated as a result of a chemical reaction with the underlying ALD HfO2 layer, which decreased the permittivity of the SrTiO3 layer. The SrTiO3 film with a SiOxNy IBL showed lower Si diffusion and better crystallinity, which provided the optimum dielectric properties of the film. (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3474233] All rights reserved.