Soft magnetic properties of as-deposited Fe-Hf-C-N films by N-2 reactive RF magnetron sputtering

Abstract

The soft magnetic properties of as-deposited FeHfCN films prepared by N-2 reactive RF magnetron sputtering have been investigated. The excellent soft magnetic properties, particularly high frequency permeability, in the as-deposited state are achieved by controlling the film composition and sputtering conditions, such as N-2 partial pressure and input power without post annealing. As-deposited films composed of 8 similar to 10 at% Hf, 17 similar to 19 at% (C+N), balanced Fe, exhibit the soft magnetic properties of 4 pi M-s = 14 kG, H-c = 0.4 Oe, especially high permeabilities of over 3000 which remain nearly constant up to 100 MHz. The analysis of TEM and XRD shows that the as-deposited films consist of finely dispersed alpha-Fe(grain size similar to 4 nm) and Hf(C, N)(grain size similar to 2 nm) precipitates, which are crystallized during sputtering deposition. The present thin films are different from Fe-TM(Nb, Zr, Ta, Hf, etc)-(C,N) films, which are amorphous in the as-deposited state and then nanocrystallized only through an optimum annealing procedure. Furthermore, the soft magnetic properties of the as-deposited films are not degraded after annealing of 823 K, 30 min.