자성체 코어 형상에 따른 마이크로 플럭스게이트 센서의 검출 특성

Abstract

A fluxgate magnetic sensor consists of a solenoid excitation coil, pick-up coil, and magnetic core. We presents the effect of magnetic core shape in a micromachined fluxgate sensor. To observe the performance of fluxgate sensor with magnetic core side width and gap, side width of 125 <TEX>${\mu}{\textrm}{m}$</TEX>, 250 <TEX>${\mu}{\textrm}{m}$</TEX>, and 500 <TEX>${\mu}{\textrm}{m}$</TEX> were designed in a rectangular-ring shaped core and the gaps of 0 <TEX>${\mu}{\textrm}{m}$</TEX>, 50 <TEX>${\mu}{\textrm}{m}$</TEX>, and 100 <TEX>${\mu}{\textrm}{m}$</TEX> were also fabricated in a racetrack shaped core. The solenoid coils and magnetic core were separated by benzocyclobutane(BCB) which had high insulation and good planarization characters. Copper coil patterns of 10 <TEX>${\mu}{\textrm}{m}$</TEX> width and 6<TEX>${\mu}{\textrm}{m}$</TEX> thickness were electroplated on Ti(300 <TEX>$\AA$</TEX>) / Cu(1500 <TEX>$\AA$</TEX>) seed layers. 3 <TEX>${\mu}{\textrm}{m}$</TEX> thick N <TEX>$i_{0.8}$</TEX>F <TEX>$e_{0.2.}$</TEX>(permalloy) film for the magnetic core was also electroplated under 2000 gauss to induce the magnetic anisotropy. The magnetic core had the high DC effective permeability of ∼1,300 and coercive field of ∼0.1 Oe. Because the magnetic cores of 500 <TEX>${\mu}{\textrm}{m}$</TEX> side width and 0 gap had a low magnetic flux leakage, high sensitivity of ∼350 V/T were measured at excitation condition of 3 <TEX>$V_{P-P}$</TEX> and 2 MHz square wave. The power consumption of ∼14 ㎽ was measured. The fabricated fluxgate sensor had the very small actual size of 3.0<TEX>${\times}$</TEX>1.7 <TEX>$\textrm{mm}^2$</TEX>. When two fluxgates were perpendicularly aligned in terrestrial field, their two-axis output signals were very useful to commercialize an electronic azimuth compass for the portable navigation system.m.m.m.