Columnar grain structure in cobalt films deposited obliquely by introducing oxygen during sputtering

Abstract

In order to clarify the effect of oxidization on the columnar grains aligned parallel to the incidence plane, which is peculiar to the sputtered films, sputtered cobalt films were prepared by introducing oxygen. Partial pressure of O2 gas ranged from 0 to 0.6Pa and total pressure of Ar and O2 gasses during deposition was 20Pa. The incidence angle was 45° and the substrate temperatures were 332 and 492K. At 332K with oxidizing the degree of the parallel alignment of columnar grains decreases and the {101̄1} pole distribution becomes broad gradually. This result is consistent with our model for the formation mechanism of the parallel alignment of columnar grains. At 492K with oxidizing the parallel alignment and the crystallographic preferred orientation disappear. However the magnetic anisotropy, which is considered to be caused by them, increases monotonically. The cause of this increase has been unclear so far.