We investigated the effects of magnetic anisotropy and anisotropy alignment to the coil geometry on the performance of a thin film inductor. For this, Ti/FeTaN bilayer films with large Hk(∼10 Oe) were used as a magnetic layer. We also fabricated a double rectangular spiral inductor which gives a uniaxial coil magnetic flux. When the hard axis of magnetic film is aligned to the magnetic field direction, highest inductance values as well as best frequency response can be obtained. As misalignment angle from the hard axis alignment increases, high-frequency characteristics are substantially degraded, especially at the misalignment angle higher than 45°. Current capability of inductor is found to depend on both Hk and hard axis alignment. The hard axis alignment, in conjunction with large Hk, increases the current capability of inductor significantly.

We investigated the soft magnetic properties of FeTaN multilayers which consist of Fe78.8Ta8.5N12.7 films with a periodic insertion of thin (∼100 Å) N-rich FeTaN layers. The FeTaN multilayer leads to an enhancement of magnetic anisotropy compared to the single layer. This enhancement can be explained in terms of increased tensile stresses in the multilayer after heat treatments. The degree of anisotropy is found to depend on the stacking number of [FeTaN/N-rich FeTaN]n layers. The stress-induced anisotropy ultimately improves the high-frequency characteristics through restricting ferromagnetic resonance. The optimum multilayer exhibits the following good soft magnetic properties: permeability of 2500, coercivity of 0.1 Oe, magnetic anisotropy field of 6 Oe, and stable frequency response up to 300 MHz.

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