Advanced Interconnect Technologies for Future ULSI Applications

Scaling trends and limitations of existing interconnect technologies are discussed and two prospective future solutions carbon nanotube (CNT) and optical interconnects are examined in detail. The inherent unscalability of metal interconnects and degradation of their performance in the light of ever-increasing transistor density and performance is emphasized. Problems with multi-layer low-k/copper interconnects, which are currently employed by industry, are outlined and ongoing efforts to push their scaling towards the near future are summarized. The prospects of CNTs as high-performance electrical interconnects are evalauated. We subsequently consider the idea of optical interconnects as a radical solution. Recent advances in silicon nanophotonics to realize optical systems for high bandwidth chip-to-chip and global on-chip interconnects using ultrafast electro-optic modulators and low-loss waveguides are presented. Lastly, challenges of integrating photonics with existing CMOS technology are discussed.