Design and Fabrication of a Column-type Microthermoelectric Cooler with Bismuth Telluride and Antimony Telluride Pillars by Using Electroplating and MEMS Technology

This paper presents an integrated column-type microthermoelectric cooler (mu-TEC) constructed with serial connected p-type Sb₂Te₃ and n-type Bi₂Te₃ micro pillars deposited by electrochemical MEMS technology. To optimize the power factor, density and uniformity of the TE films and to enhance the reproducibility of mu-TEC device, a cathode with tunable rotary speed and with accurate current controller has been designed in the electroplating system of this research. The electroplating deposited Bi₂Te₃ and Sb₂Te₃ Peltier-elements with an average thickness of 5 mum, are connected using Cr/Au layers at the hot junctions and cold junctions. The measured Seebeck coefficient and electrical resistivity are -52 muV/K and 25.2 muOmega-m or Bi₂Te₃ layers, and are 71 muV/K and 19.1 Omega;-m for Sb₂Te₃ films after annealed at 250degC. The optimized power factors of the n-type (1.07 times 10^-4 W/K²-m) and p-type (2.64 times 10^-4 W/K²-m) telluride compounds have been demonstrated in this paper. Under 5 volts driven, the integrated mu-TEC device shows average cooling achieved is about 0.7 K.