2005 Fiscal Year Final Research Report Summary
Developments of GHz and heterro-amorphous inductor core materials for integrated circuit
| Project/Area Number |
15560285
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Electronic materials/Electric materials
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| Research Institution | Sojo University |
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Principal Investigator |
MUNAKATA Makoto Sojo University, Information, Professor, 情報学部, 教授 (10183112)
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| Co-Investigator(Kenkyū-buntansha) |
YAGI Masaaki Sojo University, Information, Professor, 情報学部, 教授 (80005371)
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| Project Period (FY) |
2003 – 2005
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| Keywords | GHz frequency / magnetic device / anisotropy field / high resistivity / hybrid thin film / coplanar transmission-line / FMR frequency / insertion loss |
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| Research Abstract |
(CoFeB)-(SiO_2), (CoFe)-(SiO_2) and CoFeB films were fabricated by synchronous triple rf magnetron sputtering while rotating a cylindrical electrode. Three types of films for rf application in the range over 1 GHz were obtained, and their permeability characteristics and micro-structures were investigated.
The films exhibited large anisotropy fields H_k in the range from 40 to 550 Oe, and high ferromagnetic resonance (FMR) frequencies of 1.6-6.0 GHz in permeability characteristics. They also exhibited amorphous and nano-crystal structures, which led to good soft magnetic properties with electrical resistivities ρ of 400-100,000 μΩcm and saturation magnetizations 4ΠM_s of 6.5-20 kG. The larger H_k and higher resistivities obtained were effective for attaining the higher-frequency characteristics with lower losses for magnetic devices.
A hybrid thin film coplanar transmission-line with a CoFeB metallic magnetic film was fabricated and estimated. The fabricated devices consisted of top and bottom 3μm-thick aluminum conductor layers and inner (0.5 μm-thick Polyimide) / (0.5 μm-thick CoFeB) / (0.5 μm-thick Polyimide) trilayer. The top conductor layer consisted of a signal line and ground planes on the same plane. The CoFeB metallic magnetic film, exposed to the same thermal process of the device fabrication, had a static relative permeability of about 180 and FMR frequency of about 3.7 GHz. The Polyimide had a relative permittivity of about 3.5.
As a result, a wavelength shortening ratio of the fabricated device was about 0.19 at a few gigahertzes in frequency. The line length and the insertion loss of a quarter-wavelength device were estimated to be about 7 mm and about 2.9 dB at 2 GHz.
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