Evaluation of Electrical, Mechanical Properties, and Surface Roughness of DC Sputtering Nickel-Iron Thin Films

The NiFe thin films were prepared at room temperature by DC sputtering technique from a NiFe target onto silicon wafer, NBK7 and STIM35 glass substrates. The optimal deposition condition of NiFe thin films was obtained to be used for high density magnetic recording applications. The film thickness was determined by the SEM measurement. The electrical resistivity of the NiFe thin film with a thickness of 240 nm was 1.17 × 10^-5 Q-cm. The average residual stress and thermo-mechanical parameters were determined by the fast Fourier transform (FFT) method. The average residual stresses on two different substrates are -50 ± 2 MPa. The residual stress versus substrate temperature relation is a linear correlation after heating from room temperature to 100 °C. A double substrate technique was used to determine the thermal expansion coefficients and biaxial modulus of the NiFe thin films. The experimental results show that the thermal expansion coefficient of the NiFe thin films is 6.44 × 10^-6 °C^-1. The biaxial modulus is 779 GPa. The surface roughness was evaluated by using a microscopic interferometer. The root-mean-square roughness of the NiFe thin films were 1.350 nm for NBK7, 1.403 nm for STIM35 and 1.387 nm for silicon wafer.