A new investigation of high-frequency thermopile response

In this paper, we present a complete electrothermal study of a micromachined active thermopile for frequency and transient response. The work has been carried out combining Fourier, Laplace transfromtion with the experimental measurements and finally give a electrothermal modeling. Device parameters of thermal microsensors are essential for evaluating the sensor performances and their simulation modeling. A considerable number of measurements for microsensors and system characterizations rely on the analysis of its step response. The behavior on spectrum domain and time domain are predicted and been proved by our experiments. A new investigation of high frequency response for CMOS compatible thermoelectric infrared sensors is proposed and fabricated. The sensors are fabricated by an 1.2 mu m industrial CMOS IC technologies combined with a subsequent anisotropic front-side etching stop. It consists of a heating polysilicon resistor and an Al / n-polysilicon thermopile, embedded in an oxide/nitride membrane. High frequency response of test sample shows unexpected large signal, which is quite interesting and never reported before. To analyze the transient response, we build an electrothermal model for our test thermopile. The equivalent electrical circuitry has been built to simulate the operation of micromachined thermopile when radiation power comes. We have made a thoroughly measurement and analysis, and given some interesting results.