Development of low-cost micro-thermoelectric coolers utilizing MEMS technology

This study presents the development and comparison of two micro-thermoelectric coolers (μ-TECs): bridge-type polysilicon-based and column-type telluride-based μ-TECs. Both types were fabricated by IC-compatible MEMS technology and are suitable for localized hot-spot cooling applications. The bridge-type μ-TEC is composed of 62,500 suspending polysilicon Peltier elements in 10 mm × 10 mm chip area and fabricated by surface micromachining techniques. The column-type μ-TEC integrates 200 Bi2Te3/Sb2Te3 Peltier elements, each with clustered multi-pillar structure in a chip area of 6 mm × 6 mm using a MEMS-like electrochemical process. The Seebeck coefficient, thermal conductivity, resistivity and contact resistance of the LPCVD polysilicon and electroplated telluride themoelectric layers were investigated. For better performance, in the polysilicon bridge-type the cross-section area to length (A/L) of polysilicon thin-bridges was minimized to reduce its thermal conductance. A 5.6 K maximum temperature difference can be achieved in the bridge-type polysilicon μ-TEC under 80 mA low driving current and the maximum temperature difference of the column-type telluride μ-TEC is 1.2 K under a driving current of 200 mA. Compared to the column-type telluride μ-TEC, the bridge-type polysilicon μ-TEC studied in this research has demonstrated a higher cooling performance (136.5 K/A), cooling linearity (R2 = 99.08%), reproducibility and fabrication yield (60–75%).