A Thermoelectric Energy Generator With High-Density Stacked Thermocouples by Standard BiCMOS Process

A thermoelectric energy generator (TEG) with high area density, high Seebeck coefficient, and hightemperature gradient of thermocouples is developed by standard bipolar complementary metal oxide semiconductor (BiCMOS) process. The TEG has the stacked thermocouple design for high area density, the polysilicon germanium (poly-SiGe) thermocouple for better thermoelectric conversion efficiency, and the double cavity design for sufficient thermal gradient. It is shown that a 5 × 5 mm2 TEG chip with stacked thermocouples in optimal size 65 × 2 μm at 2 μm width spacing, or about 3512 thermocouple/mm2, can achieve 0.131-μW/cm2K2power factor and 37.01-V/cm2K voltage factor in analysis, and 0.105 μW/cm2K2and 33.91 V/cm2K in measurement. The thermocouple area density can be increased further by reducing the width spacing to 1.067 μm, or about 4802 thermocouple/mm2, to achieve 0.103 μW/cm2K2and 36.19 V/cm2K in measurement. The optimal thermocouple size is 78 × 2 μm to achieve 0.131 μW/cm2K2and 44.95 V/cm2K in analysis. The performance increase is shown to be superior to all the other semiconductor TEGs.