Micropatterning of sandwiched FeCuNbSiB/Cu/FeCuNbSiB for the realization of magneto-impedance microsensors

Abstract

This work presents the fabrication of magnetic field microsensors based on the magneto-impedance phenomenon and dedicated to NDC applications. The multilayer structure, ferromagnetic/conductive/ferromagnetic, is composed of a copper layer sandwiched with two Finemet Ò alloy films. The later, initially an amorphous material, is nanocrystallized by heat treatment. The fabrication process has been optimized in order to minimize coercivity and induce transversal anisotropy. The technological defects induced by the lift-off and sputtering processes change the magneto-impedance properties of the sensors. Eliminating these defects permits the sensor to reach to a sensitivity of 1,200 V/T/A at 30 MHz with a bias field larger than the anisotropy field and without hysteresis. The angular dependence of the sensitivity shows that the sensor is only sensitive to the axial component of the magnetic field.

Magnetoimpedance Biosensors and Real-Time Healthcare Monitors: Progress, Opportunities, and Challenges

“…The uniformly distributed nanograins embedded in the amorphous matrix assure near-zero magnetostrictive anisotropy. Moreover, the magnetocrystalline anisotropy in nanocrystalline materials is averaged out, which also contributes to its high sensitivity to weak magnetic fields [ 59 ].…”

Fabrication of Cu–Zr–Ti thick film metallic glass structure by double metal mask lift-off process

“…Introduction 51 Thin-film amorphous alloys have been widely adopted as struc-52 tural material for use in micro-electro-mechanical systems 53 (MEMS) because of their high tensile strength, high elastic strain, 54 and good soft magnetic properties [1][2][3][4]. For patterning of these 55 thin film amorphous alloys, a lift-off process is typically used, 56 which includes a sputter deposition step and the use of a mask 57 material [5]. A problem with amorphous alloys is that they are 58 liable to crystallize due to the heating that occurs during sputter 59 deposition [6].…”