Design and Characterization of Micro Thermoelectric Cross-Plane Generators With Electroplated ${\rm Bi}_{2}{\rm Te}_{3}$ , ${\rm Sb}_{x}{\rm Te}_{y}$ , and Reflow Soldering

We demonstrate and discuss the fabrication of cross-plane microthermoelectric generators with electrochemically deposited thermoelectric materials. A new process based on two layers of photoresist is presented to deposit the legs on the final substrate. The n-type Bi
₂
Te
₃
, Cu, and p-type Sb
_x
Te
_y
are integrated into the generator. The deposition of antimony telluride is performed to the largest thickness reported to date. The influence of thermal annealing on the material properties is studied. A new flip-chip reflow soldering process with Bi
₅₇
Sn
₄₂
Ag
₁
soldering paste is presented that allows for enhanced thermal coupling of the generators. The manufactured generators are electrically and thermally fully characterized. They generate up to 1.63 μW cm
^-2
K
^-2
, which corresponds to a maximum power density of 2434.4 μW cm
^-2
.