Highly Sensitive Infrared Temperature Sensor for CMOS Compatible Thermopiles

Abstract

A high-sensitivity infrared detector requires small thermal capacitance and small thermal conductance to maximize the temperature change and signal induced by incident IR radiation. The suspended structure of infrared sensors provides ideal, thermally isolated, structures for support of the thin film detector. A new idea of improving CMOS thermopile performance is introduced to reduce the thermal conductance by dividing the thermocouple into several segments, which greatly increase the heat flow barrier. Then, adjacent segments are connected by a minimum width of alumina wire, which change the heat path and accumulated heat at the joint points. Several designs of infrared microsensors can improve performance of signal with reduce of thermal conductance. To that end, by using some adequate designs of polysilicon architecture, we can greatly reduce the heat flow from the main stream without introducing further electric resistance, which is related with noise. The design and simulation of thermopile sensors are realized by using the process parameters of standard 0.351m CMOS IC technology. Firstly we develop such a structure of thermopile with low thermal conductance and high performance by using CMOS compatible process which can be easily and naturally fabricated. The simulation results show good match with our original idea and great performance than before.