Highly Sensitive Thin Film Sensor Using Coplanar Line

Abstract

A very sensitive thin film sensor was developed using a transmission line. The sensor element consisted of a coplanar line fabricated from Sr33Ti16O51 (STO) film (6 μm thick), morphous CoNbZr film (5 μm thick), and Cu/Cr film (4 μm/0.2 μm). The deposited STO film had high permittivity of around 31. The STO film enhanced the sensitivity of the sensor and a phase change of more than 100 degrees/Oe and gain of over -40 dB were achieved simultaneously. These characteristics are very similar to those of a large sensor with a bulky ceramic substrate6).