Preparation of thin ferrite films on silicon using RF sputtering

Abstract

Thin‐films of Nix Zn1–x Fe2O4 [(Ni,Zn)‐ferrite] are grown by means of RF sputtering on Si(100) and (111) substrates, corresponding to the orientation of Si cantilevers for AFM/MFM measurements. We find that the ferrite can be sputtered directly onto the Si surfaces, but an additional annealing step is required to obtain a purely polycrystalline, soft magnetic film. The microstructure of the films is investigated employing transmission electron microscopy, electron backscatter diffraction and magnetic force microscopy. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Different types of ferrite thin films as magnetic cantilever coating for magnetic force microscopy

“…The resulting ferrite film is polycrystalline, with a nearly random orientation of the individual ferrite grains. The TEM-determined grain sizes range between 5 and 20 nm, which is too small for an electron backscatter diffraction analysis as performed in [7] on a 100-nm-thick NiZnFe 2 O 4 film. Nevertheless, the random orientation of the grains is similar to that of the much thicker NiZnFe 2 O 4 film.…”

“…The resulting ferrite coatings had thicknesses of typically 50 up to 100 nm. For the NiZnFe 2 O 4 ferrite, we found that a slow cooling stage after the annealing in air leads to an enhanced grain growth [7]. For both ferrites, polycrystalline ferrite grains are obtained without any amorphous ferrite layer located at the Si substrate.…”

Microwave magnetic properties of soft magnetic thin films

“…It shows that all the samples are well-crystallized and single-phase with spinel crystal structure. Observation of only selected peaks is seen in all the samples which usually appear in ferrite films [15,31]. It is worth noting that with the increase of P Ar : PO 2 the (311) peak shifts to a larger diffraction angle and its width becomes narrow.…”

“…Ni-Zn ferrite thin films which have the highest 4M s in ferrites were investigated. To our knowledge, the soft ferrite films deposited by many methods [12][13][14][15][16][17] require high temperature post-heating treatments or substrate heating at least of 600°C to obtain a better spinel structure and soft magnetic properties, which is impossible for electronic circuit integrations. We report the achievement the in-situ fabrication of Ni-Zn ferrite films with well-defined spinel crystal structure at room temperature without any heating treatments by magnetron sputtering [18,19].…”

Integrated Ferrite Film Inductor for Power System-on-Chip (PowerSoC) Smart Phone Applications

“…However, thick ferrite deposition is still challenging on silicon wafers. RF sputtering [8] and PLD (pulsed laser deposition) [9] processes have been used to deposit ferrite, but deposition and deposition area are limited to low rate and small area.…”