Effect of N₂ Gas Pressure Ratio and DC Bias on Formation of Iron Nitride Thin Film by RF Sputtering Method

Abstract

In this paper, we investigated the effect of N₂ gas pressure ratio and DC bias on the formation of iron nitride thin films deposited by RF sputtering method. As a result, the amounts of γ'-Fe₄N and ε-Fe₃N, which had high N₂ content than that of α”-Fe₁₆N₂, increased with increasing N₂ gas pressure ratio. From the result of x-ray diffraction, the Fe-N film at the N₂ gas pressure ratio of 15% became the single phase of γ'-Fe₄N. Therefore, we attempted the formation of α'-martensite and α”-Fe₁₆N₂ by applying DC bias voltage. It revealed that it was possible to control the N₂ content and the coercive force by applying DC bias voltage. However, the formation of α”-Fe₁₆N₂ was not observed.