Reactive sputtering of high moment Fe-N soft magnetic films with in-situ plasma diagnosis and control

Fe-N films with 4 piM(s) of up to 26 kG were deposited by reactive rf-sputt ering on single crystal Si(001) and glass substrates with Fe seed layers. O ptical emission spectra of the Ar/N-2 plasma were obtained from the vicinit y of the target surface via an optical fiber. Nitrogen content of the plasm a was pre-set according to the peak height (set point) of a particular wave length emission peak of the optical emission spectrum of the plasma and mai ntained constant throughout the film deposition process via the closed loop controller. The saturation magnetization of the Fe-N films initially incre ased with the increase of N content in the plasma (set point), reaching max imum at set point around 40 and then decreased with further increase of nit rogen. The nitrogen content of the films with maximum 4 piM(s) was about 4. 26 at%. The major phase of the as-deposited Fe-N films, analyzed by X-ray d iffraction was alpha -Fe. Minor diffraction peaks at 2 theta of 28.9 degree s corresponding to alpha " -Fe16N2 phase were present for Fe-N films, which might be responsible for the increase of saturation magnetization of the F e-N films.