Highly Sensitive Thin-Film Magnetic Field Sensor Meandering Coplanar Line

A very sensitive thin-film sensor was developed using a meandering coplanar line fabricated from Sr 33 Ti 16 O 51 film (3 $\mu \text{m}$ thick), amorphous Co 85 Nb 12 Zr 3 film ( $1~{\mathrm{ mm}} \times 2.45$ mm, 0.3–2 $\mu \text{m}$ thick), and Cu/Cr film (2/0.1 $\mu \text{m}$ ). The deposited SrTiO film enhanced the sensitivity of a magnetic field sensor, a phase change of more than 30°/Oe and a gain of over −40 dB being achieved simultaneously. The maximum phase change (sensitivity) was observed for a CoNbZr film thickness of $\sim 0.5$ –1 $\mu \text{m}$ . The sensitive bias field and carrier frequency increased as the CoNbZr film thickness increased. The optimum CoNbZr film thickness was realized by the tradeoff between the sensitive bias field and the volume of the CoNbZr film.