The study of a novel crystal SiGeC far infrared sensor with thermal isolated by MEMS technology

Abstract

In this study, we report the design, fabrication and performance of a novel crystal SiGeC infrared sensor with thermal isolation structure. The developed sensor was prepared using the technology of micro-electromechanical systems (MEMS) to achieve a better thermal isolation structure. The operation principle of the sensor is based on the change of thermistor’s resistance under the irradiation FIR light. The thermistor in the IR detector is made of Si0.68Ge0.31C0.01 thin films for its large activation energy 0.21 eV and the temperature coefficient (TCR) of −2.74%, respectively. Finite element method (FEM) package ANSYS has been employed for the analysis of the thermal isolation and stress distribution in the IR detector. The major FIR-sensing part on the micro-bridge with dimensions of 2,000 × 2,000 × 25 μm3 is fabricated by anisotropic wet etching. Responsivity, thermal conductance, thermal time constant were investigated and found that the thermal isolation improved structure possesses a much superior performance.