Correlation between crystalline structure and soft magnetic properties in sputtered sendust films

We have investigated the change in crystallographic and magnetic properties of sendust thin films before/after annealing. Films were deposited by both rf diode and rf magnetron sputtering. rf diode-sputtered films did not possess soft magnetic properties in the as-deposited state. Films were subsequently annealed in both a conventional oven and a rapid thermal annealing ~RTA! system. The coercivity of the films decreased from over 10 Oe to a minimum value of 0.6 Oe after annealing and a systematic shift in the ~110! x-ray diffraction ~XRD! peak position towards that of bulk sendust was observed. No additional XRD peaks were observed after annealing. The optimum annealing conditions to minimize coercivity was found to be 1–2 h at 550 °C. By comparison, films processed by RTA resulted in minimum coercivity of 0.9 Oe obtained after annealing for 2 min at 550 °C. XRD for films annealed by both RTA and oven annealing showed a similar decrease in the d spacing of the ~110! plane, indicating a release of tensile strain in the films that had been introduced during deposition. rf magnetron-deposited samples possessed coercivities as low as 1.4 Oe as deposited and showed in-plane anisotropy. XRD again showed a ~110! texture, however, the peak intensity of magnetron-sputtered samples was a factor of 20 less than the diode-sputtered films of the same thickness. The position of the ~110! peak, however, was close to that of rf diode deposited films after annealing indicating that the magnetron-sputtered films were relatively stress-free. © 1997 American Institute of Physics. @S0021-8979~97!24708-0#