Abstract
In this work, aspect ratio of various intercalation doped MLGNR interconnects are optimized using a numerical approach to achieve improved performance and reliability. A numerical optimization method is presented to estimate optimized aspect ratio considering combined effects of performance, noise and reliability metrics for any arbitrary nano interconnect system. This approach is cost effective and will be extremely useful to industry for selection of aspect ratio of interconnects as it is a non-SPICE method and reduces fabrication iterations for achieving desired performance and reliability. Our numerical method suggests that by minimizing the figure of merit (i.e. Noise Delay Power Product / Breakdown Power P_{BD} ratio), aspect ratio of FeCl3 doped MLGNR interconnect is optimized at 0.987, 0.61 and 0.579 for local, intermediate and global level, respectively at 7 nm node. Comparing the optimized performance metrics in this work with the estimated metrics at prescribed aspect ratio by IRDS roadmap, delay, noise delay product (NDP), power delay product (PDP), PDP/ P_{BD} ratio and figure of merit are improved by (sim2% and sim25%), (sim44% and sim50%), (sim9% and sim48%), (sim6% and sim48%) and (sim49% and sim68%) for 10 mu m and 1 mm long Fecl3 doped MLGNR interconnect, respectively at 7 nm node. Increase in contact resistance leads to significant decrease in performance and increase in optimized aspect ratio of local Fecl3 doped MLGNR interconnect. Scaling down from 10 to 7 nm node results in increase of optimized aspect ratio in all levels of interconnects. Even though the performance of MLGNR degrades with scaling down but when compared to copper, the performance improves with technology scaling. Finally, this study provides circuit designers a detailed guideline for selecting an optimized aspect ratio for achieving better performance, power efficiency and reliability in doped MLGNR interconnects.
Highlights
Multilayer Graphene Nanoribbons (MLGNRs) are preferred over single layer graphene because of their lower resistivity
Delay/PBD, noise delay product (NDP) and power delay product (PDP), PDP/PBD and NPDP/PBD are compared by considering aspect ratio (AR) prescribed by IRDS 2018 r oadmap[1] and the optimized AR obtained from this work
Specular (i.e. P = 0.8 ) MLGNR interconnects is considered for all the calculations
Summary
Copper interconnects have reached their performance limits due to high resistivity, grain boundary scattering effects and electromigration issues[1]. Nishad et al in[14] optimized thickness of Lithium and AsF5 intercalated Top-Contact MLGNR (TC-MLGNR) interconnects and compared with copper and pristine interconnects Both Jiang et al and Nishad et al have not shown any dimensional optimization for improved performance and reliability issues which is a concerning factor to consider for commercialization of MLGNR interconnects in near-future VLSI circuits. A numerical model is developed for optimization of aspect ratio (AR) by minimizing delay and FOM ( NPDP/PBD ratio) for local, intermediate and global level MLGNR interconnects considering different intercalation dopants This model is supported by the simulation results provided in “Results and discussion” section. This proposed numerical methodology is applicable to all types of nano-interconnects making it a generalized model. Properties Stage of intercalation Mean free path (μm) Fermi level (eV) Avg layer Spacing (nm)
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