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 t echnique. This work is part of an on-going research effort to develop a mic roprobe based on the Peltier effect for highly localized temperature manipu lation on the microscale. Bismuth telluride alloys were electrodeposited ga lvanostatically into microfeatures on a titanium substrate using an acidic solution containing Bi3+ and HTeO2- ions in 1 mol/dm(3) nitric acid (pH sim ilar to 0). The Bi-Te alloy microposts were monophasic, had a polycrystalli ne structure, demonstrated excellent adhesion to the substrate, and good me chanical strength. The chemical composition of the microposts was dependent on the electrolyte composition of the deposition bath and the current dens ity used in electroplating; by controlling these two factors either p- or n -type Bi-Te alloy microposts may be produced. This research demonstrates th at the microfabrication of Peltier effect probes is feasible.