A thermal evolution study of argon and nitrogen incorporation in bias-sputtered Co-Cr films

The incorporation of argon and nitrogen, two typical impurity gases, in sputtered CoCr films is studied using thermal-evolution mass spectroscopy. In particular, the variation of adsorbed quantities of each individual gas as a function of negative substrate bias is measured, and the result is correlated with the observed improvement in the perpendicular orientation as well as the perpendicular magnetic properties of the films. Argon incorporation in the growing films is studied as a function of the amount of sputtering power and sputtering argon pressure. It is concluded that the apparent improvement in the properties of CoCr at around -100-V substrate bias is due to a decrease in incorporation of harmful impurity gases such as nitrogen rather than to any specific variation in the argon content of the films