Fast response infrared detector using a radially distributed dual-layer thermopile

Microelectromechanical system (MEMS) thermopile infrared (IR) detectors excel in contactless, highly sensitive, non-invasive temperature measurements over a wide range, without cooling systems, making them ideal for precise intelligent sensing applications. In this study, we present a micromachined thermopile IR detector utilizing a radially distributed dual-layer thermopile that demonstrates fast response time and significantly improved responsivity and detectivity. A dual-layer thermocouple array is designed by applying the N/P-poly, which are radially distributed on a SiO2 supporting layer and suspended by dry etching the backside of a silicon substrate. The results of the study, which compared traditional four-ended beam structures with radially distributed structures that were modeled and simulated, indicate that the latter design enhances the output voltage and significantly improves responsivity and detectivity, with an increase of 40.5% and 43.8%, respectively. With a fast response time of 9.5 ms at room temperature, the detector exhibited a measured responsivity of 100.6 V/W and detectivity of 5.2×107 cm∙Hz1/2/W in an experimental system constructed to evaluate its performance.