Impact of three-dimensional architectures on interconnects in gigascale integration

An interconnect distribution model for homogeneous, three-dimensional (3-D) architectures with variable separation of strata is presented. Three-dimensional architectures offer an opportunity to reduce the length of the longest interconnects, The separation of strata has little impact on the length of interconnects but a large impact on the number of interstratal interconnects. Using a multilevel interconnect methodology for an ITRS 2005 100 nm ASIC, a two-strata architecture offers a 3.9 x increase in wire-limited clock frequency, an 84% decrease in wire-limited area or a 25% decrease in the number of metal levels required. In practice, however, such fabrication advances as improved alignment tolerances in wafer-bonding techniques are needed to gain key advantages stemming from 3-D architectures for homogeneous gigascale integrated circuits.