Effect of Bias Voltage and Deposition Rate on the Structure and Coercivity of NiFe Films

Abstract

The effect of the bias voltage Ub and the deposition rate $${v}$$ on the structure, grain size D, and coercivity Hc of NiFe films with a thickness d from 30 to 980 nm, grown on Si/SiO2 substrates by DC magnetron sputtering, has been studied. In the case of Ub = 0, a decrease in $${v}$$ from values $${v}$$ ≈ 27 to ≈7 nm/min is accompanied by an increase in the values of the critical film thickness dcr from dcr ≈ 220 nm to dcr ≈ 270 nm. In this case, Hc in films with d < dcr is characterized by the dependence Hc ~ D6 and varies from ~1 to ~20 Oe. For Ub = –100 V, the effect of the deposition rate on the coercivity is much more noticeable. At $${v}$$ = 7 and 14 nm/min, the films exhibit soft magnetic properties (Hc ≈ 0.15–1.4 Oe) and the absence of dcr for the entire range of studied thicknesses. The films obtained at $${v}$$ = 21 and 27 nm/min pass into the “supercritical” state at d ≥ dcr ≈ 520 nm, and in the range d < dcr they are characterized by the dependence Hc ~ D3 and an increase in the coercivity from ~0.35 to ~10 Oe.