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 high-temperature 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 x 5 mm(2) TEG chip with stacked thermocouples in optimal size 65 x 2 mu m at 2 mu m width spacing, or about 3512 thermocouple/mm(2), can achieve 0.131-mu W/cm(2)K(2) power factor and 37.01-V/cm(2)K voltage factor in analysis, and 0.105 mu W/cm(2)K(2) and 33.91 V/cm(2)K in measurement. The thermocouple area density can be increased further by reducing the width spacing to 1.067 mu m, or about 4802 thermocouple/mm(2), to achieve 0.103 mu W/cm(2)K(2) and 36.19 V/cm(2)K in measurement. The optimal thermocouple size is 78 x 2 mu m to achieve 0.131 mu W/cm(2)K(2) and 44.95 V/cm(2)K in analysis. The performance increase is shown to be superior to all the other semiconductor TEGs.