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|Superlattice Coolers for Dynamic Thermal Management of Microprocessor Hotspots|
|Keywords: Dynamic thermal management, Superlattice coolers, Hotspot|
|Due to the presence of hotspots, heat flux distribution over microprocessors is highly non-uniform. Heat flux at the hotspot can be five to ten times higher than the average over the entire chip. Since most of the commercially available cooling schemes are designed for uniform heat flux, cooling devices need to be over-sized to dissipate peak heat fluxes, which may arise over shorter durations. This necessitates development of localized and dynamically addressable cooling solutions. A novel hybrid cooling scheme has been proposed to dissipate both the background heat flux, as well as the hotspot power. This scheme combines a solid-state cooling technique (superlattice cooler (SLC)), with a fluidic cooling technique, (liquid cooled microchannel heat sink). SLCs are solid-state active devices which work on Peltier effect. These are silicon micro-fabrication compatible and can remove up to 500 W/cm2 heat flux locally over areas of several hundreds of m diameter. Superlattice coolers are strategically located over the expected locations of hotspots. An array of superlattice coolers can be utilized if the hotspot location is not known or fixed. Liquid cooled microchannel heat sinks can readily remove background heat fluxes over 100 W/cm2 over the chip. Integrating the liquid cooled microchannel heat sink and SLC can deliver an effective cooling solution to tackle non-uniform heat flux present over the chip. An experimental test set up is fabricated to study the transient and steady performance of this hybrid cooling scheme. The test chip includes hotspot heaters, background heaters and superlattice coolers. The test chip is attached to the microchannel heat sink at the back. The whole fabrication process is CMOS compatible. Preliminary results show that superlattice cooler can remove hotspots with heat flux density greater than 250 W/cm2.|
|Vivek Sahu, Student
Georgia Institute of Technology