Manufacturing and measurement of CMOS-MEMS-based micro thermoelectric generators with long-length thermocouples

Abstract

The study explores the fabrication and evaluation of a micro thermoelectric generator (MTG) with long-length thermocouples (TCs) through the utilization of a commercial complementary metal oxide semiconductor process. The MTG consists of 23 TCs, and its performance is intricately linked to the temperature difference (T diff) between the cold and hot sides of these TCs. An increase in T diff leads to higher output voltage and power for the MTG. To enhance T diff, the TCs are designed to be 700 µm in length, and an innovative design has been implemented on the cold side of the TCs, creating a suspended structure to improve heat dissipation A post-process is essential for achieving this suspended TC structure. The results demonstrate that the TC structure is fully suspended and remains undamaged. The measured outcomes reveal an output voltage of 13.8 mV when the T diff reaches 3.5 K. Under these conditions, the MTG exhibits a voltage factor of 2.76 mV mm−2K−1. Furthermore, at a T diff of 3.5 K, the maximum output power reaches 2.1 nW. The MTG demonstrates a power factor of 0.12 nW mm−2 K−2.