Thermoelectric Micro-Cooler for Hot-Spot Thermal Management

Driven by shrinking feature sizes, microprocessor “hot-spots” — with their associated high heat flux and sharp temperature gradients — have emerged as the primary “driver” for on-chip thermal management of today’s IC technology. Solid state thermoelectric micro-coolers offer great promise for reducing the severity of on-chip “hot-spots”, but the theoretical cooling potential of these devices, fabricated on the back of the silicon die in an IC package, has yet to be determined. The results of a three-dimensional electro-thermal finite-element modeling study of such a micro-cooler are presented. Attention is focused on the hot-spot temperature reductions associated with variations in micro-cooler geometry, chip thickness, and chip doping concentration, along with the parasitic Joule heating effects from the electrical contact resistance and current flow through the silicon. The modeling results help to define the optimum solid-state cooling configuration and reveal that, for the conditions examined, nearly 80% of the hot-spot temperature rise of 2.5°C can be removed from a 70μm × 70μm, 680W/cm² hot-spot on a 50μm thick silicon die with a single micro-cooler.