Two-layer process for a micro thermoelectric cross-plane generator with electroplating and reflow soldering

This paper addresses the design, modeling, and fabrication of a micro-thermoelectric cross-plane generator with electroplated materials. Bi₂Te₃ is used as n-type material, while Cu is used as p-type material. Deposition of both materials on seed layers with the same electrical potential was realized by a two-layer process with SU-8 as permanent photoresist and a second resist that is laminated on the SU-8 twice. The upper electrical contacts of the 71 thermocouples connected electrically in series are formed by flip-chip bonding a second Si chip using a solder paste. Measurements of the Seebeck coefficient of the Bi₂Te₃ thermolegs are presented along with values of the open circuit voltage for different temperature differences.