Alignment of crystallites in obliquely deposited cobalt films

The geometric alignment of crystallites was investigated using ellipsometry for evaporated cobalt films. The incidence angle was 45° and the gas pressure ranged from 0.008 to 2 Pa during argon gas inflow. The anisotropy of the reflection coefficient showed that above 0.6 Pa, crystallites preferentially align in the direction parallel to the incidence plane. The parallel alignment of crystallites is also found in sputtered films and is always accompanied by a c-axis preferred orientation. Replica electron microscopic observation and X-ray analysis revealed that the top of columnar grains constituting the parallel alignment is surrounded by the {101¯1} habit planes, and the side of the columnar grains is truncated by the {0001} habit planes. Thus, we concluded that the parallel alignment is determined by the crystal habit.