Reducing Temperature Variation in 3D Integrated Circuits Using Heat Pipes

With the advent of 3D stacking, thermal hotspots have emerged as a significant concern, due to challenges involved in removing heat from the intervening layers. Use of thermal through silicon vias (TSVs) to transfer heat from one layer to the next has been proposed as a hotspot mitigation technique. However, thermal TSV placement directly at the hotspots, compete with other design objectives due to higher wiring congestion at those sites. This paper presents a novel temperature aware physical design methodology which consists of using auxiliary routing known as Heat Pipes, to transfer heat away from hot regions in 3D integrated circuits. Heat Pipe is dummy routing connecting hot and cold regions in the same or different layers using interconnects and thermal TSVs that are placed opportunistically away from the congested areas. In order to evaluate hotspot temperature reduction due to Heat Pipes, a thermal model to simulate the effect of metal interconnect on heat distribution in 3D integrated circuits has been developed. Results show that the proposed solution using Heat Pipes lead to a reduction of 1 to 2 Kelvin at the hotspots. It is well known that even a small reduction in temperature of hotspots may significantly reduce the need for dynamic thermal management, often leading to large gain in system performance.