A comprehensive comparative study of the performance of carbon‐ and copper‐based interconnects in ultra‐large‐scale integrated circuits

Abstract

Continuous increase of transistor count in ultra-large-scale integrated (ULSI) circuits demands denser interconnection networks to guarantee normal operation. As the distances between adjacent interconnect lines shrinks, severe crosstalk effects appear. New interconnect materials and technologies are proposed to alleviate deteriorating crosstalk effects and maintain overall circuit performance at a desirable level. Carbon-based materials including carbon nanotubes (CNTs) and graphene nanoribbons (GNRs) are among promising candidate materials to replace copper in future ULSI interconnects. In this work, carbon-based interconnects including multiwall carbon nanotubes (MWCNTs) and multilayer graphene nanoribbons (MLGNRs), both horizontal (HMLGNRs) and vertical (VMLGNRs), are compared with traditional copper interconnects in terms of crosstalk delay and noise. Due to lower surface roughness, boron nitride (BN) is considered as substrate material for carbonbased interconnects. To obtain more accurate and reliable results, layer number dependence of dielectric constant of BN multilayers and surface roughness dependence of the resistivity of HMLGNR interconnects are considered. The role of interconnect length, line spacing, and interlayer distance (substrate thickness) in crosstalk delay and noise of coupled carbon-and Cu-based interconnect lines is investigated. It is shown that VMLGNR interconnects with perfect GNR edges exhibit the least crosstalk delay while MWCNT interconnects show far less crosstalk noise than other materials.