Silicon Micro-Thermoelectric Coolers For Local Heat Removal In Integrated Circuit Chips

High performance Si integrated circuits (ICs) can generate heat fluxes ≥ 100 Wcm^–2 over areas ~ 10^–4 cm². This heating degrades IC performance and produces significant excess heat. Currently chip cooling and waste heat removal is done by air conditioning, which is inefficient, wasteful, and expensive because it globally cools everything, not just the IC chips. As a result data centers now consume ~ 1% of worldwide annual electrical energy production, estimated to increase to ~ 3% by 2030. In an effort to reduce thermal management energy requirements, we have developed Si micro-thermoelectric coolers (μTECs) that can be integrated in-chip using the same process flow used to make an IC. These μTECs have been made with areas as small ~ 10^–5 cm² and can be inserted directly below or in close proximity to known local hot spots in an IC. While Si µTECs cannot achieve low base temperatures, they can actively pump relatively high heat fluxes directly to a heat sink, thus preventing or minimizing on-chip temperature increases. In this way only the heat sink rather than an entire room needs to be macroscopically cooled, potentially resulting in a significant reduction in energy usage. Prototype integrated μTECs have been shown to pump in-chip generated heat fluxes of 45 Wcm^–2 with no increase in local chip temperature. Models suggest that improvements in μTEC design can lead to maximum cooling power densities > 100 Wcm^–2.