Thin film magnetostrictive sensor with on-chip readout and attoFarad capacitance resolution

We report the first successful integration of magnetostrictive Metglas (Fe/sub 78/Si/sub 9/B/sub 13/) thin film sensor with a readout circuit using standard integrated circuit (IC) process and surface micromachining. The Metglas thin film is on a nitride cantilever beam. Its magnetic domains are subject to rotation in a magnetic field. This induces a strain and hence, beam deflection which is measured through capacitive change using a charge coupling readout scheme with aF capacitance resolution.