Control of preferential orientation of platinum films on RuO2/SiO2/Si substrates by sputtering

We investigated the preferential orientation of Pt films deposited on RuO2/SiO2/Si substrates at a substrate temperature of ;100 degrees C by RF magnetron sputtering, using only Ar gas without O-2 gas. It was found that, for a sputtering power less than 30 W and a sputtering gas pressure of 10Pa, the Pt(100)-oriented volume ratio over the whole Pt film rapidly increases with film thickness. However, for a sputtering power more than 50 W and the same pressure, the ratio slightly increases with thickness, and it is suppressed by increasing the power. On the other hand, the Pt(I 1 I)-oriented volume ratio is smaller and decreases with thickness irrespective of the power, whereas it is increased by decreasing the pressure to 4 Pa at 20 W. From these results, it can be considered that (I I I)-oriented crystalline growth is mainly driven by the lowest surface energy and that (100)oriented growth is mainly driven by the strain energy due to intrinsic tensile stress which is increased with thickness and pressure, and decreased with power.