Ultrasmall and Ultrathin Ni-Based Resistance Temperature Detector Integrated in Micro Thermoelectric Devices for in Situ Temperature Measurement

With the ever-increasing demand of miniature chip cooling and self-powered technology, more attention has arisen on micro thermoelectric (TE) devices. Nevertheless, accurate temperature and performance evaluations for micro TE devices are still challenging due to their high element density and small size. Herein, an in situ integration method using ultrasmall and ultrathin resistance temperature detectors (RTDs) is developed to precisely characterize temperatures across thin TE legs under actual testing scenarios. With theoretical analysis based on a 1-D thermal resistance model, the ratio of effective temperature difference across the TE leg increases to 33.97% comparing with 11.04% using commercial thermocouples. Then, the fabrication of the RTD is shown, and a temperature coefficient of resistance of 0.336% C-1 with high linearity, a response time of 43 ms, a resolution of 0.1 °C, and good compatibility is exhibited. By integrating the detector on a leg of a TE device, the in situ temperature of a micro TE device is measured, indicating an increase of 201.2% of the output TE voltage, after temperature correction, as well as an exponential enhancement of power density. This in situ temperature measurement method can be extended to further guide performance evaluations for various microsystems.