Highly Sensitive Coplanar Line Thin-Film Sensor Using SrTiO Film

A very sensitive thin-film sensor was developed using a coplanar line fabricated from SrTiO (Sr₃₃Ti₁₆O₅₁) film (0.5, 1, 2, 3, and 6 μm thick), amorphous CoNbZr film (5 μm thick), and Cu/Cr film (4 μm/0.2 μm). The deposited SrTiO film had high permittivity of around 31. This film enhanced the sensitivity of the magnetic field sensor, a phase change of more than 100°/Oe and gain of over -40 dB being achieved simultaneously. The sensor with SrTiO film enhanced the sensitivity about 1.6 times greater than that with SiO₂ film because of the high permittivity of the SrTiO film. The sensitivity of the sensor increased with increasing thickness of the SrTiO film, a thickness of around 3 μm being sufficient for enhancement of the sensitivity.