Characterization of vibration-type infrared thermal detector on temperature, light, and thermal infrared

A micromechanical infrared (IR) thermal detector using a torsional resonator was fabricated to achieve sensitive detection of a thermal IR radiation. The resonator has a bimaterial structure consisting of an oscillating body and an IR absorber. The suspended resonator is heated and deformed by IR radiation. The deformation generates a hard spring effect for torsional oscillation, thereby shifting its resonant frequency by a hard spring effect. In this study, to improve thermal sensitivity, the resonator was composed of a tension-enhanced poly-crystalline silicon and aluminum. Using a laser-based measuring system, the fabricated device was characterized in terms of responses to visible light irradiation, substrate heating, and thermal IR irradiation. Resonant frequency shift of 7,400 ppm was observed when a thermal source of 570 °C was placed 15 cm away from the detector.