Influence of thermal annealing on the resistivity of titanium/platinum thin films

Abstract

In this study, the authors investigate the influence of thermal annealing up to temperatures of 700°C on the room-temperature resistivity of electron-beam-evaporated titanium/platinum thin films. Oxidized silicon wafers are used as the substrate. The titanium has a fixed thickness of 5nm and serves as an adhesion layer. The thickness of the platinum top is varied between 21 and 97nm. Up to annealing temperatures of 450°C, the film resistivity of the bilayer system is a linear correlation with the reciprocal platinum film thickness, as expected from the size effect. In this annealing regime, the change in intrinsic film stress dominates the electrical behavior. At annealing temperatures of 600°C and above, however, the diffusion of titanium into the top layer leads to an enhanced increase in film resistivity, especially at low platinum thicknesses. The onset of plastic deformation of the platinum layer causes an additional effect that decreases the electrical conductivity above average.