Dependence of {111}-textured Pt electrode properties on TiO2 seed layers formed by thermal oxidation

Abstract

The Pt/TiO2/SiO2/Si electrode structure prepared using sputter deposition of Ti, conversion of Ti to TiO2 by thermal oxidation, and sputter deposition of Pt was evaluated by using measurements of sheet resistance and X-ray diffraction. Nonlinearity of the reciprocal sheet resistance dependence on thickness revealed a change in the Ti conductivity that was attributed to a change in the Ti microstructure. Upon conversion to TiO2, it was determined that TiO2 exhibits a critical thickness of 32 nm that minimizes normal strain and {100}-textured misorientation and correlates with the onset of the Ti reciprocal sheet resistance nonlinearity. Both the TiO2 {100}-strain and {100}-texture directly affects the {111}-textured growth of Pt deposited at 500 °C. Pt deposited onto TiO2 films with the critical thickness of 32 nm exhibits a maximization of the normal strain relative to bulk Pt and also displays the narrowest distribution of Pt {111}-textured grain misalignment. The results presented show how Ti deposition conditions, TiO2 anneal conditions, and TiO2 thickness combine to modify the Pt electrode structural properties. Additionally, the measurement techniques demonstrated for the Ti, TiO2, and Pt are applicable to process control monitoring as well as standardized comparison of electrode structures used in integrated piezoelectric and ferroelectric devices.