Study on thermal sensitivity of a VOx/SiO2/PS/Si multi-layer structure

Vanadium oxide (VOx) thin films are considered as one of the optimal sensitive materials used in micro-thermal detectors for its excellent thermal sensitivity. Porous Si (PS) as thermal insulator used in MEMS is fast developed. In this paper, a VOx/ SiO2/ PS/Si multi-layer structure with well thermal sensitivity is presented. Excellent thermal insulation of PS and high thermal sensitivity of VOx thin film make the structure to attain maximal thermal response signal which is the input signal of microdetector readout circuit. In the structure PS is formed in substrate Si by electrochemical etching as a thermal insulator. VOx thin film is deposited by direct current reactive magnetron sputtering as a thermal detector. SiO2 by PECVD acts as an electro-insulator between PS and VOx. Experiments prove the multi-layer structure has excellent thermal sensitivity and its thermal response is much better than a similar structure without PS under the condition of 20 μW input power.