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\times $
5 mm2 TEG chip with stacked thermocouples in optimal size
$65\times 2\,\,\mu \text{m}$
at
$2 \mu \text{m}$
width spacing, or about 3512 thermocouple/mm2, can achieve 0.131-
$\mu \text{W}$
/cm
$^{{2}}\text{K}^{{2}}$
power factor and 37.01-V/cm
$^{{2}}\text{K}$
voltage factor in analysis, and
$0.105 \mu \text{W}$
/cm
$^{{2}}\text{K}^{{2}}$
and 33.91 V/cm
$^{{2}}\text{K}$
in measurement. The thermocouple area density can be increased further by reducing the width spacing to
$1.067 \mu \text{m}$
, or about 4802 thermocouple/mm2, to achieve
$0.103 \mu \text{W}$
/cm
$^{{2}}\text{K}^{{2}}$
and 36.19 V/cm
$^{{2}}\text{K}$
in measurement. The optimal thermocouple size is
$78\times 2\,\,\mu \text{m}$
to achieve
$0.131 \mu \text{W}$
/cm
$^{{2}}\text{K}^{{2}}$
and 44.95 V/cm
$^{{2}}\text{K}$
in analysis. The performance increase is shown to be superior to all the other semiconductor TEGs.