抄録
Pt/Ti thin films were grown on SiO2/Al2O3 substrates by sputtering under argon-oxygen gas mixtures and annealed in air ambient. In comparison with Ar-sputtered films reported in the previous paper, Ar-O2-sputtered films show flat Pt surfaces and high values of temperature coefficient of resistance (TCR). In order to probe the cause of these phenomena, microstructures of these films were investigated by means of X-ray diffraction analysis, scanning electron microscopy, transmission electron microscopy and glow discharge optical emission spectroscopy. The Ar-O2-sputtered Pt/Ti films differ from the Ar-sputtered ones in the following aspects : (1) Ti deposition rate becomes slower by about a third ; (2) Pt grains with preferred (111) orientation grow about three times larger in diameter ; (3) Ti atoms form TiO2 precipitates with the rutile-type structure mostly at the Pt/SiO2 interface, but the precipitates rarely exist in Pt film. From these features, it is shown that the surface flatness and TCR of the Pt film sputtered under argon-oxygen gas mixtures are improved by controlling the formation of TiO2 precipitates in the Pt film.
