微細化薄膜MI素子

抄録

A micromachined magnetoimpedance (MI) element was developed and its MI properties were investigated. Consisting of a SiN/Al/NiFe/SiO₂ film, it was prepared on a Si (100) wafer and fabricated by photolithography and etching. Ni₈₀Fe₂₀ film with nearly zero magnetostriction prepared by bias magnetron sputtering under a magnetic field was adopted as a magnetic layer in the MI element, and magnetic anisotropy was induced parallel to the current direction. Sensitivity corresponding to the maximum fractional change in impedance increased with thickness and length, and was greatest for a width of 20 μm. The values for whick the MI element had the best properties were 38 % for the sensitivity, 1446 ppm/°C for the temperature coefficient of impedance and 712 ppm/°C for the temperature coefficient of sensitivity. These values were much better than those of conventional magnetoresistance (MR) sensors. Therefore, these micromachined MI elements have great potential for use in integrated magnetic sensors.