Properties of NiFe-N films prepared by rf sputtering in nitrogen-argon gas mixtures

The structure and properties of NiFe-N films, prepared by rf reactive sputtering process using nitrogen in the range from 0 to 40% in the nitrogen-argon gas mixture during sputtering, have been studied. The concentration of nitrogen and the resistivity of the NiFe-N films were determined as a function of nitrogen partial pressure. Films with good soft magnetic properties were obtained when the nitrogen in the nitrogen-argon gas mixture during sputtering was in the range 0-10%. The resistivity of these films was low and x-ray diffraction results indicated only an fcc structure of γ-NiFe alloy. For films deposited with more than 10% of nitrogen in the gas mixture there is a transition region where resistivity and coercivity started to increase. Films deposited with 20% nitrogen mixed with argon consist of a mixture of γ-NiFe alloy and (Ni,Fe)4N phases. With further increase of nitrogen above 30% during sputtering, a (Ni,Fe)3N phase was observed. The resistivity and coercivity of these films were high.