Inter-CNT capacitance in mixed CNT bundle interconnects for VLSI circuits
11 Sep 2012-International Journal of Electronics (Taylor & Francis Group)-Vol. 99, Iss: 10, pp 1439-1447
TL;DR: In this article, a realistic inter-carbon nanotube (CNT) electrostatic coupling capacitance and tunnelling conductance model for a mixed CNT bundle is presented.
Abstract: This article presents a realistic inter-carbon nanotube (CNT) electrostatic coupling capacitance and tunnelling conductance model for a mixed CNT bundle. The change of potential across such a bundle necessitates the need to consider the inter-CNT capacitance in the equivalent circuit of CNT interconnects for very large scale integration circuits. The equivalent transmission line circuit model of a unit bundle containing one single-walled CNT (SWCNT) and one multi-walled CNT (MWCNT) has been shown. This new model is then used to calculate the delay induced by the inter-CNT capacitance and tunnelling conductance, which predicts the relative positioning of MW/SWCNTs in mixed CNT bundle.
Citations
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TL;DR: This is the first review on MCB VLSI interconnects and the ability to conduct high current at high temperatures through the 1D structure is making the CNT interconnect technology an attractive one.
31 citations
TL;DR: In this paper, the impact of tunneling and intershell coupling between adjacent shells on temperature-dependent equivalent circuit parameters of a multi-walled carbon nanotube bundle is also critically analyzed and employed for different MCB structures under case 1.
Abstract: The temperature-dependent circuit modeling and performance analysis in terms of crosstalk in capacitively coupled mixed carbon nanotube bundle (MCB) interconnects, at the far end of the victim line, have been analyzed with four different structures of MCBs (MCB-1, MCB-2, MCB-3 and MCB-4) constituted under case 1 and case 2 at the 22-nm technology node. The impact of tunneling and intershell coupling between adjacent shells on temperature-dependent equivalent circuit parameters of a multi-walled carbon nanotube bundle are also critically analyzed and employed for different MCB structures under case 1. A similar analysis is performed for copper interconnects and comparisons are made between results obtained through these analyses over temperatures ranging from 300 K to 500 K. The simulation program with integrated circuit emphasis simulation results reveals that, compared with all MCB structures under case 1 and case 2, with rise in temperature from 300 K to 500 K, crosstalk-induced noise voltage levels at the far end of the victim line are found to be significantly large in copper. It is also observed that due to the dominance of larger temperature-dependent resistance and ground capacitance in case 1, the MCB-2 is of lower crosstalk-induced noise voltage levels than other structures of MCBs. On the other hand, the MCB-1 has smaller time duration of victim output. Results further reveal that, compared with case 2 of MCB, with rise in temperatures, the victim line gets less prone to crosstalk-induced noise in MCB interconnects constituted under case 1, due to tunneling effects and intershell coupling between adjacent shells. Based on these comparative results, a promising MCB structure (MCB-2) has been proposed among other structures under the consideration of tunneling effects and intershell coupling (case 1).
28 citations
TL;DR: In this paper, the performance of carbon nanotubes (CNTs) has been investigated for on-chip VLSI interconnect applications. But, the authors focused on the performance degradation of traditional copper interconnects in terms of latency, power dissipation and induced crosstalk noise.
Abstract: In nanoscale regime, the performance of traditional copper interconnects degrades substantially in terms of latency, power dissipation and induced crosstalk noise. This is due to miniaturization of electronic devices and many-fold enhancement of interconnect lengths in very large-scale integrated (VLSI) circuits. However, carbon nanotubes (CNTs) due to their unique physical properties such as high thermal conductivity, current carrying capability and mechanical strength have drawn the attention of researchers in recent times. The present paper provides comprehensive investigations in the various CNT structures for on-chip VLSI interconnect applications. Different configurations of CNT structures are studied namely single-wall CNT (SWCNT), multiwall CNT (MWCNT) and mixed-wall CNT bundle (MCB). The performance of CNT interconnects is analyzed using driver-interconnect-load system. It is investigated that the reduction in propagation delay in MCB interconnect is nearly 69%, 60%, 40% and 22% as compar...
27 citations
Cites background from "Inter-CNT capacitance in mixed CNT ..."
...In order to accomplish maximum conductivity and least latency, the inter-CNT electrostatic coupling capacitances in mixed CNT bundle have been evaluated in [104]....
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TL;DR: In this paper, the authors proposed a new method to reduce crosstalk of carbon nanotube (CNT)-based VLSI interconnects by proper integration of semiconducting CNTs (s-CNTs) and a new contact geometry.
Abstract: In this letter, we present a new method to reduce crosstalk of carbon nanotube (CNT)-based VLSI interconnects. For this, proper integration of semiconducting CNTs (s-CNTs) and a new contact geometry, where metallic CNTs are in the core and s-CNTs are in the periphery of the CNT bundle, is proposed. The coupling capacitance between adjacent interconnects is modeled and compared with and without s-CNTs in the CNT bundle periphery. SPICE analysis and EM simulations are carried out which show that the coupling capacitance can be reduced by 82.5% and the resulting delay by 8.41%. We suggest that the crosstalk effect between neighboring wires can be reduced by using s-CNTs in the design.
21 citations
Cites methods from "Inter-CNT capacitance in mixed CNT ..."
...We have considered a CNT bundle with suitable driver and load values from our previous work [13]....
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TL;DR: In this article, a review of low-k dielectric materials for CNT interconnects is presented and the specific properties of these materials and the necessities for integrating them into CNT-interconnects to meet the requirements of future IC designers.
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,
19 citations
Cites background or methods from "Inter-CNT capacitance in mixed CNT ..."
...Also, other groups, including ours, have studied the properties of mixed CNT bundles (MCBs) as interconnects that have both SWCNTs and MWCNTs in them [15-21, 124, 125]....
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...Through SPICE simulations, it was found that MCBs can outperform SWCNT bundle and MWCNT interconnects in terms of delay and power dissipation [15-21, 125]....
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References
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TL;DR: In this article, the current carrying capacity and reliability of multiwalled carbon nanotubes under high current densities (>109 A/cm2) were investigated and shown 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.
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.
1,229 citations
"Inter-CNT capacitance in mixed CNT ..." refers methods in this paper
...The transmission line (TL) modelling of single-walled CNT (SWCNT) bundle as well as multi-walled CNT (MWCNT) interconnects has already been carried out earlier (Wei, Vajtai, and Ajayan 2001; Banerjee and Srivastava 2006; Xu, Li, and Banerjee 2009)....
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TL;DR: In this paper, the fabrication and electronic properties of devices based on individual carbon nanotubes are reviewed, and both metallic and semiconducting SWNTs are found to possess electrical characteristics that compare favorably to the best electronic materials available.
Abstract: Single-walled carbon nanotubes (SWNTs) have emerged as a very promising new class of electronic materials. The fabrication and electronic properties of devices based on individual SWNTs are reviewed. Both metallic and semiconducting SWNTs are found to possess electrical characteristics that compare favorably to the best electronic materials available. Manufacturability issues, however, remain a major challenge.
1,206 citations
"Inter-CNT capacitance in mixed CNT ..." refers background in this paper
...Basically, there are three fundamental resistances associated with a CNT (McEuen et al. 2002)....
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...fundamental resistances associated with a CNT (McEuen et al. 2002)....
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1,082 citations
"Inter-CNT capacitance in mixed CNT ..." refers background in this paper
...For a bundle of CNTs, as shown in Figure 1(b), the equation becomes (Jordan and Balmain 1968) Cint:bundle ¼ 2" lnðb=aÞ ð2Þ It is seen here that since the distance between any two CNTs is 0.34 nm, spacing between the inner and outer CNTs is considered as the radius of the circle formed by the outer…...
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TL;DR: In this paper, the state-of-the-art of carbon-based nanomaterials, particularly the one-dimensional (1-D) forms, carbon nanotubes (CNTs) and graphene nanoribbons (GNRs), are reviewed.
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.
411 citations
TL;DR: In this paper, a detailed investigation of MWCNT-based interconnect performance is presented, for the first time, and a compact equivalent circuit model is presented for evaluating and compared with traditional Cu interconnects, as well as Single-Walled CNT (SWCNT) based interconnect, at different interconnect levels.
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.
350 citations
"Inter-CNT capacitance in mixed CNT ..." refers background in this paper
...Tunnelling conductance is diameter dependent as depicted by Equation (3) (Li et al. 2008)....
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