Microfabrication of high aspect ratio Bi-Te alloy microposts and applications in micro-sized cooling probes

High aspect ratio microposts of bismuth telluride alloy with heights of up to 500 mu m and a diameter of 150 mu m have been fabricated with the LIGA technique. This work is part of an on-going research effort to develop a microprobe based on the Peltier effect for highly localized temperature manipulation on the microscale. Bismuth telluride alloys were electrodeposited galvanostatically into microfeatures on a titanium substrate using an acidic solution containing Bi3+ and HTeO2- ions in 1 mol/dm(3) nitric acid (pH similar to 0). The Bi-Te alloy microposts were monophasic, had a polycrystalline structure, demonstrated excellent adhesion to the substrate, and good mechanical strength. The chemical composition of the microposts was dependent on the electrolyte composition of the deposition bath and the current density used in electroplating; by controlling these two factors either p- or n-type Bi-Te alloy microposts may be produced. This research demonstrates that the microfabrication of Peltier effect probes is feasible.