Fe-Al-Oグラニュラ膜の微細パターン化による磁気特性の制御  [in Japanese] Control of the Magnetic Properties of Fe-Al-O Granular Films by Micro-patterning  [in Japanese]

The film material for 1 GHz-drive inductors used in mobile communication handsets needs a resistivity as high as 500μΩcm and resonance frequency higher than 2 GHz in order to avoid loss generation at 1 GHz. Fe-Al-O film is a possible candidate for the inductors, but it has a trade-off correlation between the resistivity and resonance frequency. Fe_<61>Al_<13>O_<26> is a suitable composition for this purpose. To induce stabilized uniaxial anisotropy, Fe-Al-O films were micro-patterned into small rectangles by using photolithography and ion milling. The anisotropy field was increased from 2800A/m to 6400A/m, which enhanced the resonance frequency from 1.8 GHz to 2.7 GHz.