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

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.