Parallel capacitive temperature micro‐sensor for passive wireless sensing applications

Abstract

The parallel capacitive temperature micro-sensor is designed and fabricated based on the metal multi-user MEMS processes. The interdigitated capacitors parallelly connected with the plane capacitor are used as the temperature sensing structures. Thermal expansion of the top layer cause the out-of-plane deformation, and introduce horizontal and vertical displacements of the structure, which leads to the capacitance variation. Top metal layer is the cascaded bent beam with interdigitated end, which is used as the interdigitated capacitors. Polysilicon layer paired with metal layer to form the plane capacitor. Experimental results show that the sensor provides an average sensitivity of 32.45 fF/°C in the 0–100°C range. It is also demonstrated that the temperature sensor can be integrated with an inductor to form an LC passive wireless sensor, which provides a sensitivity of 46.61 kHz/°C in the whole temperature range.