Fabrication and Characterization CoZrO Films Deposited by Facing Targets Reactive Sputtering for Micromagnetic Inductors

In recent years, there has been a strong demand for soft magnetic films suitable for high-frequency micromagnetic devices as power electronics circuits to operate at higher frequencies. Specifically, there is a need for magnetic thin films with ferromagnetic resonance frequencies (
f
_r
) in the range of several gigahertz. Nanogranular CoZrO thin films have emerged as promising candidates due to their high
f
_r
and high electrical resistivity. We fabricated CoZrO thin films using facing targets reactive sputtering with oxygen as the reactive gas. As the oxygen partial pressure ratio (
P
_O2
) was gradually increased up to 0.8%, clear uniaxial magnetic anisotropy appeared, leading to improved soft magnetic properties. At a
P
_O2
of 0.8%, the film exhibited the most superior soft magnetic properties. With further increase in
P
_O2
, magnetic loops implying a stripe magnetic-domain structure were obtained. In this
P
_O2
range, phase separation was observed, along with a sharp increase in electrical resistivity.
f
_r
of the CoZrO film formed at
P
_O2
= 0.8% was determined to be 3.2 GHz from high-frequency permeability measurement. We have confirmed the effectiveness of facing targets’ reactive sputtering in preparing CoZrO films with excellent soft magnetic properties.