5. Conclusions
An energy harvesting thermoelectric micro generator manufactured using the commercial
CMOS-process has been implemented. The micro generator was constructed by 33 thermocouples in
series. Each thermocouple consisted of p-type and n-type polysilicon strips. The output power of the
generator depended on the temperature difference between the hot and cold parts in the thermocouples.
The hot part of the generator located on a suspended plate for reducing the heat-sinking. A post-CMOS
process was utilized to release the hot part of the generator, and the post-process included an
anisotropic dry etching with CHF3/O2 RIE to remove the sacrificial oxide layer and an isotropic dry
etching with XeF2 RIE to etch the silicon substrate. The experimental results showed that the output
power of the thermoelectric generator was about 9.4 μW as the temperature difference of 15 K and the
power factor of the generator was 1.4 × 10−2 μW mm−2 K−2. The thermoelectric micro generator is
suitable for application in microelectronic devices as an auxiliary electrical power source. The power
of the device can be enhanced using many generators in series. In addition, the power of the generator
can also be improved by structure design to increase the temperature difference of hot and cold
junctions and by changing thermocouple materials to increase the Seebeck coefficient difference.