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Proceedings ArticleDOI: 10.1109/NSTSI.2011.6111807

Effect of Realistic Inter-CNT Coupling Capacitance in Mixed CNT Bundle

27 Dec 2011-pp 1-4
Abstract: The change of potential across a CNT in a bundle necessitates the need to consider the inter-CNT coupling capacitance in the equivalent circuit of CNT interconnects for VLSI circuits. This paper presents a realistic inter-CNT electrostatic coupling capacitance and tunneling conductance model for this bundle and studied its effects in detail. The equivalent transmission line circuit model of a unit bundle containing one SWCNT and one MWCNT has been shown. This new model is then used to calculate the delay induced by the inter-CNT capacitance and tunneling conductance, which predicts the relative positioning of MW/SWCNTs in mixed CNT bundle. more

Topics: Quantum capacitance (56%), Bundle (56%), Parasitic capacitance (56%) more

Journal ArticleDOI: 10.4028/WWW.SCIENTIFIC.NET/JNANOR.52.21
Abstract: Carbon nanotube (CNT) interconnects are emerging as the ultimate choice for next generation ultra large scale integrated (ULSI) circuits. Significant progress in precise growth of aligned CNTs and integration of multiwalled CNT interconnects into a test chip make them promising candidates for future nanoelectronic chips. Tremendous research efforts were made on silicon based ultra-low-k dielectrics for Cu interconnects, but, the most recent advancements in polymer based composites as dielectric materials open up fresh challenges in the use of low-k dielectrics for CNT interconnects. This paper reviews the emerging polymer composites like Boron Nitride Nanotubes, Graphene/Polyimide composites, Metal Organic Frameworks and small diameter CNTs. Many reviews are already exists on the synthesis, fabrication, dielectric, mechanical, chemical and thermal properties of these materials. In this review, we have explained the specific properties of these materials and the necessities for integrating them into CNT interconnects to meet the requirements of future IC designers.Keywords: low-k dielectric materials, ultra low-k dielectrics, carbon nanotubes, interconnects, dielectric constant, more

Topics: Dielectric (59%), Carbon nanotube (53%)

14 Citations

Open accessJournal Article
01 Dec 2013-Scientia Iranica
Abstract: This research paper introduces novel structures of mixed CNT bundle (MCB) based non-conventional arrangements of single- and multi-walled carbon nanotubes. Hierarchical equivalent single conductor (ESC) model is used to analyze the propagation delay and power dissipation of CNT bundles. The hierarchical model of MCB considers two types of CNTs, one single-walled CNT (SWCNT) and other multi-walled CNT (MWCNT). ESCmodel of MCB is the combination of ESC models of bundled SWCNT and bundled MWCNT. Initially, simple ESC models of bundled SWCNT and bundled MWCNT are derived considering the parasitic elements like resistance, capacitance and inductance. Later on, these two equivalent models are combined to build up the final ESC model of novel MCBs. It has been observed that the overall delay and power dissipation are reduced by 48.1% and 20.9% respectively for the novel MCB that has horizontal arrangement of SWCNTs and MWCNTs in equal halves. more

2 Citations

Open accessJournal Article
Abstract: This paper proposes single walled carbon nanotube bundles as VLSI interconnects at 20nm, 16nm, 14nm and 12nm Technology nodes. Effects of voltage scaling on propagation delay and power dissipation of the interconnects is analyzed. Input voltages ranging from 0.3 V (deep subthreshold) to 0.8 V (moderate subthreshold) are considered. After formulating the equivalent single conductor RLC transmission line circuit of the interconnects, simulations of a driver-interconnect-load setup using SmartSPICE was carried out. Later, electric field simulations of coupled interconnects considering Miller capacitance effects for in-phase and out-of-phase conditions was done. Results show that voltage scaling is essential as the technology node size decreases to ensure low-power devices. more

Topics: Subthreshold conduction (58%), Integrated circuit (51%), Voltage (51%) more

1 Citations

Proceedings ArticleDOI: 10.1109/EPTC47984.2019.9026693
01 Dec 2019-
Abstract: Triangular cross sectioned carbon nanotube bundles are proposed as VLSI interconnects. Due to their inherent geometry effects, triangular CNT (T-CNT) bundles are least capacitively coupled and hence offer least possible coupling capacitance between adjacent interconnects. So, this transpires to lesser crosstalk and induced delay in T-CNT bundle interconnects compared to traditionally proposed CNT bundle interconnect structures. So, in this work, we study the feasibility of using T-CNT bundles as interconnects in ICs. For that, we analyze the AC frequency response of T-CNT bundles and compare them with traditionally used square cross sectioned CNT (S-CNT) bundles. HSPICE based circuit simulations are carried out at various input voltages ranging from subthreshold to superthreshold voltages of 0.3V, 0.6V and 0.9V. Also, we do the analysis for local, semi-global and global interconnect lengths ranging from $500\mu\mathrm{m}$ to $2000\mu\mathrm{m}$ . Results show that T-CNT bundles have higher voltage gain for all lengths compared to S-CNT bundles. More specifically, T-CNT bundles have highest voltage gain at 0.3V for all lengths. This shows that T-CNT bundles are suitable as VLSI interconnects and are more suited at subthreshold voltages. more

Topics: Bundle (52%), Subthreshold conduction (51%)

1 Citations


Journal ArticleDOI: 10.1063/1.1396632
Abstract: The current-carrying capacity and reliability studies of multiwalled carbon nanotubes under high current densities (>109 A/cm2) show that no observable failure in the nanotube structure and no measurable change in the resistance are detected at temperatures up to 250 °C and for time scales up to 2 weeks. Our results suggest that nanotubes are potential candidates as interconnects in future large-scale integrated nanoelectronic devices. more

1,172 Citations

Journal ArticleDOI: 10.1109/TED.2009.2026524
Abstract: This paper reviews the current state of research in carbon-based nanomaterials, particularly the one-dimensional (1-D) forms, carbon nanotubes (CNTs) and graphene nanoribbons (GNRs), whose promising electrical, thermal, and mechanical properties make them attractive candidates for next-generation integrated circuit (IC) applications. After summarizing the basic physics of these materials, the state of the art of their interconnect-related fabrication and modeling efforts is reviewed. Both electrical and thermal modeling and performance analysis for various CNT- and GNR-based interconnects are presented and compared with conventional interconnect materials to provide guidelines for their prospective applications. It is shown that single-walled, double-walled, and multiwalled CNTs can provide better performance than that of Cu. However, in order to make GNR interconnects comparable with Cu or CNT interconnects, both intercalation doping and high edge-specularity must be achieved. Thermal analysis of CNTs shows significant advantages in tall vias, indicating their promising application as through-silicon vias in 3-D ICs. In addition to on-chip interconnects, various applications exploiting the low-dimensional properties of these nanomaterials are discussed. These include chip-to-packaging interconnects as well as passive devices for future generations of IC technology. Specifically, the small form factor of CNTs and reduced skin effect in CNT interconnects have significant implications for the design of on-chip capacitors and inductors, respectively. more

380 Citations

Journal ArticleDOI: 10.1109/TED.2008.922855
Abstract: Metallic carbon nanotubes (CNTs) have received much attention for their unique characteristics as a possible alternative to Cu interconnects in future ICs. Until this date, while almost all fabrication efforts have been directed toward multiwalled CNT (MWCNT) interconnects, there is a lack of MWCNT modeling work. This paper presents, for the first time, a detailed investigation of MWCNT-based interconnect performance. A compact equivalent circuit model of MWCNTs is presented for the first time, and the performance of MWCNT interconnects is evaluated and compared against traditional Cu interconnects, as well as Single-Walled CNT (SWCNT)-based interconnects, at different interconnect levels (local, intermediate, and global) for future technology nodes. It is shown that at the intermediate and global levels, MWCNT interconnects can achieve smaller signal delay than that of Cu interconnects, and the improvements become more significant with technology scaling and increasing wire lengths. At 1000- global or 500- intermediate level interconnects, the delay of MWCNT interconnects can reach as low as 15% of Cu interconnect delay. It is also shown that in order for SWCNT bundles to outperform MWCNT interconnects, dense and high metallic-fraction SWCNT bundles are necessary. On the other hand, since MWCNTs are easier to fabricate with less concern about the chirality and density control, they can be attractive for immediate use as horizontal wires in VLSI, including local, intermediate, and global level interconnects. more

338 Citations

Journal ArticleDOI: 10.1109/TED.2009.2024254
Chuan Xu1, Hong Li1, Kaustav Banerjee1Institutions (1)
Abstract: Graphene nanoribbons (GNRs) are considered as a prospective interconnect material. A comprehensive conductance and delay analysis of GNR interconnects is presented in this paper. Using a simple tight-binding model and the linear response Landauer formula, the conductance model of GNR is derived. Several GNR structures are examined, and the conductance among them and other interconnect materials [e.g., copper (Cu), tungsten (W), and carbon nanotubes (CNTs)] is compared. The impact of different model parameters (i.e., bandgap, mean free path, Fermi level, and edge specularity) on the conductance is discussed. Both global and local GNR interconnect delays are analyzed using an RLC equivalent circuit model. Intercalation doping for multilayer GNRs is proposed, and it is shown that in order to match (or better) the performance of Cu or CNT bundles at either the global or local level, multiple zigzag-edged GNR layers along with proper intercalation doping must be used and near-specular nanoribbon edge should be achieved. However, intercalation-doped multilayer zigzag GNRs can have better performance than that of W, implying possible application as local interconnects in some cases. Thus, this paper identifies the on-chip interconnect domains where GNRs can be employed and provides valuable insights into the process technology development for GNR interconnects. more

Topics: Graphene nanoribbons (53%), Landauer formula (50%)

299 Citations

Open accessProceedings ArticleDOI: 10.5555/1129601.1129657
Navin Srivastava1, Kaustav Banerjee1Institutions (1)
31 May 2005-
Abstract: The work in this paper analyses the applicability of carbon nanotube (CNT) bundles as interconnects for VLSI circuits, while taking into account the practical limitations in this technology. A model is developed to calculate equivalent circuit parameters for a CNT-bundle interconnect based on interconnect geometry. Using this model, the performance of CNT-bundle interconnects (at local, intermediate and global levels) is compared to copper wires of the future. It is shown that CNT bundles can outperform copper for long intermediate and global interconnects, and can be engineered to compete with copper for local level interconnects. The technological requirements necessary to make CNT bundles viable as future interconnects are also laid out. more

292 Citations

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