Iron Based Soft Magnetic Nanofilms Deposited by Impacting Nanoparticles

Wireless communication has been rapidly progressing toward the commercialization of 5G and the development of 6G. The frequency spectrum of 5G and 6G varies from a few hundred Megahertz to tens of Gigahertz. Increasing need for lighter, faster, and smarter devices in highly miniaturized packages, the integration of thin film soft magnetic cores with high saturation magnetization and uniaxial anisotropy on an electronic circuit is important. Nanocomposite soft magnetic films assembled by Fe/Fe₃O₄ core-shell nanoparticles may be the most suitable candidate for the desired high-frequency magnetic properties. It is crucial that the fabrication of such films must be compatible with Si-based integration, where a restricted processing temperature is required to incorporate the underlying integrated circuits. The high-temperature magnetic post-annealing is usually necessary to induce in-plane uniaxial anisotropy in these nanocomposite films, which is apparently incompatible with the Si-integrated designs for high-frequency applications. For materials vulnerable to high-temperature processes, the negatively charged nanoparticles can be accelerated by applying positive bias voltage onto the substrate held at different angles. As a result, the shapes of the deposited nanoparticles can be changed from original spheroids to a general ellipsoid, which is expected at room temperature to induce in-plane uniaxial anisotropy in the nanocomposites assembled by the Fe/Fe₃O₄ core-shell nanoparticles.