Advanced Soft Magnetic Materials for Magnetic Recording Heads and Integrated Inductors

Abstract

High performance magnetic heads, inductors and transformers, indispensable to information technology encompassing from information storage, portable power delivery, to wireless communication, require soft magnetic films with low coercivities, high permeability, and large ferromagnetic resonance frequencies.The Fe-Co-N-based films have a ferromagnetic resonance frequency of >1 GHz at zerobias field, showing great promise for applications in write heads and integrated inductors in a frequency range of >1 GHz. Magnetization dynamics measurements at sub-nanosecond scale have been performed on Fe-Co-N high saturation soft magnetic films with Permalloy nanolayer seeds having a saturation magnetization of 24 kG. The high frequency behavior appears to be affected by magnetic anisotropy dispersion.One of the biggest challenges facing integration of magnetic material onto silicon is the compatibility of magnetics with standard silicon processing techniques. Integrated inductors were realized using ground planes of Co-Ta-Zr (ρ=100µΩ-cm). The magnetic properties of CoTa-Zr showed no change even after undergoing high temperature processing. Inductors with 1µm Co-Ta-Zr produced inductance values up to 60% higher than the air core inductors at frequencies up to 1.4 GHz.