The interconnect bottleneck presents a compelling reason to explore novel interconnect architectures. In this work, we have quantified and compared the performance of two promising interconnects: carbon nanotube (CNT) and optical interconnects with the scaled Cu/low-k on-chip and off-chip interconnects for future high-performance ICs.

The purpose of this work is two fold. First, to quantify and establish future trends for the dynamic power dissipation in global wires of high performance integrated circuits. Second, to develop a novel and efficient delay-power tradeoff formulation for minimizing power due to repeaters, which can otherwise constitute 50% of total global wire power dissipation. Using the closed form solutions from this formulation, power savings of 50% on repeaters are shown with minimal delay penalties of about 5% at the 50 nm technology node. These closed-form, analytical solutions provide a fast and powerful tool for designers to minimize power.

Performance of deep-submicrometer very large scale integrated (VLSI) circuits is being increasingly dominated by the interconnects due to decreasing wire pitch and increasing die size. Additionally, heterogeneous integration of different technologies in one single chip is becoming increasingly desirable, for which planar (two-dimensional) ICs may not be suitable. This paper analyzes the limitations of the existing interconnect technologies and design methodologies and presents a novel three-dimensional (3-D) chip design strategy that exploits the vertical dimension to alleviate the interconnect related problems and to facilitate heterogeneous integration of technologies to realize a system-on-a-chip (SoC) design. A comprehensive analytical treatment of these 3-D ICs has been presented and it has been shown that by simply dividing a planar chip into separate blocks, each occurring a separate physical level interconnected by short and vertical interlayer interconnects (VILICs), significant improvement in performance and reduction in wire-limited chip area can be achieved, without the aid of any other circuit or design innovations. A scheme to optimize the interconnect distribution among different interconnect tiers is presented and the effect of transferring the repeaters to upper Si layers has been quantified in this analysis for a two-layer 3-D chip. Furthermore, one of the major concerns in 3-D ICs arising due to power dissipation problems has been analyzed and an analytical model has been presented to estimate the temperatures of the different active layers. It is demonstrated that advancement in heat sinking technology will be necessary in order to extract maximum performance from these chips. Implications of 3-D device architecture on several design issues have also been discussed with special attention to SoC design strategies. Finally some of the promising technologies for manufacturing 3-D ICs have been outlined.