Investigating the role of interconnect surface roughness towards the design of poweraware network on chip

Abstract

High-speed metal interconnects play a significant role in the on-chip network system as the network performance largely depends on the behaviour of these interconnects. Variability in wire properties due to the surface roughness directly impacts the overall system performance. In this study, the authors evaluate the effects of interconnect surface roughness on deeply scaled on-chip interconnects (i.e. 22, 13, and 7 nm) in the context of the network on chip (NoC). The critical roughness parameters of interconnect in NoC are extracted by atomic force microscopy analysis of fabricated thin sheets of copper. Their analysis shows that in a 5 × 5 NoC with 25 cores on 2.5 mm × 2.5 mm die, rough interconnects can lead to a significant penalty on energy budget, bandwidth density, bit error rate, the figure of merit and total system throughput. Their analysis shows that this penalty is further increased by moving towards interconnection lines at advanced technology nodes. They simulate the bodytrack workload of PARSEC benchmark by using Tejas Simulator to show the penalty on latency and energy of the architecture due to the rough interconnects. Their study makes an attempt to qualitatively and quantitative highlight the impact of the interconnect surface roughness on the design of power-aware NoCs.