Abstract
Magnetically soft NiZn ferrite (Ni0.5Zn0.5Fe2O4) nanoparticles are embedded within a permalloy (Ni-Fe) matrix via an electro-infiltration process as thin films intended for use as on-chip inductor cores in the MHz frequency regime. A layer of NiZn ferrite nanoparticles is first deposited, and then permalloy is electroplated through the voids to encapsulate the particles and form three-dimensional ferrite/alloy nanocomposites. The composites are estimated to contain 37% ferrite by volume and exhibit a relative permeability of ∼320, a saturation of ∼1.15 T, and an operational bandwidth of 93 MHz. Compared to a permalloy thin film of similar thickness, the nanocomposite exhibits 39% higher electrical resistivity and 50% higher bandwidth.
Highlights
Soft magnetic nanocomposite cores utilizing magnetic nanoparticles are being developed for inductors, transformers, and RF components operating at a frequency range from MHz to GHz.[1,2,3] high operation frequency facilitates the potential size reduction and integration of magnetic passives, the generated eddy currents contribute high power loss and limit the performance of magnetic cores
Soft NiZn ferrite (Ni0.5Zn0.5Fe2O4) nanoparticles are embedded within a permalloy (Ni-Fe) matrix via an electro-infiltration process as thin films intended for use as on-chip inductor cores in the MHz frequency regime
Cross-sections of example electroplated NiZn ferrite/Ni-Fe nanocomposite films are shown in Fig. 2, before and after polishing
Summary
Soft magnetic nanocomposite cores utilizing magnetic nanoparticles are being developed for inductors, transformers, and RF components operating at a frequency range from MHz to GHz.[1,2,3] high operation frequency facilitates the potential size reduction and integration of magnetic passives, the generated eddy currents contribute high power loss and limit the performance of magnetic cores. Electro-infiltration offers an alternative for fabricating structured nanocomposites with two magnetic phases in a post-CMOS-compatible process.[4] Electro-infiltration uses an electroplated metal to fill in the void spaces in a porous layer of nanomaterials. Such methods have been utilized to fabricate both soft[4] and hard (permanent)[5,6] nanocomposites. The electro-infiltration process is used to form soft magnetic NiZn ferrite/Ni-Fe nanocomposites, where NiZn ferrite and permalloy are both common materials for magnetic core of inductors and transformers. Nanocomposites containing a non-magnetic phase, NiZn ferrite/Cu, are made using the electro-infiltration process as reference materials for better understanding the magnetic properties of soft magnetic ferrite/alloy nanocomposites
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