Modelling and analysis of crosstalk induced noise effects in bundle SWCNT interconnects and its impact on signal stability (original) (raw)
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Fifth Asia Symposium on Quality Electronic Design (ASQED 2013), 2013
Single-walled carbon nanotubes (SWCNTs) have the potential to revolutionize the interconnects in future nanoscale integrated circuits. In the proposed work, crosstalk effects are investigated in SWCNTs at 21 nm and 15 nm technology nodes for intermediate as well as global interconnects. An ABCD parameter based approach has been used to investigate crosstalk delay and noise in both sparse as well as dense SWCNT bundled interconnect system. It is evident from the simulation results that the proposed model is not only 100% accurate but also almost 10 times faster than SPICE. The worst case crosstalk induced delay and peak crosstalk noise voltages for SWCNT bundle interconnects are compared to those of conventional copper (Cu) interconnects at the intermediate as well as global level interconnects. Simulation results also confirm that dense SWCNTs are always ahead of sparse SWCNTs with respect to performance advantage numbers over copper for every levels of interconnects and irrespective of technology nodes. As far as the worst case peak crosstalk noise is concerned, there is a critical length after which the performance of the dense SWCNT bundles is better than that of its sparse counterpart. Proposed model, analysis, along with supportive simulation results prove that dense SWCNT bundled interconnect is one of the most promising alterative interconnect solution for future generation of nanoscale circuits compared to copper with respect to performance as well as signal integrity issues.
International Journal of Circuit Theory and Applications, 2014
The temperature-dependent, crosstalk-induced, noise voltage waveform and its frequency spectrum, in capacitive coupled single-walled carbon nanotube (SWCNT) bundle interconnects, at the far end of victim line, have been analyzed at 22-nm technology node. A similar analysis is performed for copper interconnects and a comparison is made between the results of these two analyses. The SPICE simulation results reveal that at temperature variations ranging from 300 to 500 K, compared with conventional metal (copper) conductors, crosstalk noise voltage levels in CNT, at the far end of victim line, are significantly low. Simulated results further reveal that, with rise in interconnect temperatures, compared with copper interconnects, coupled interconnects of SWCNT bundle filter more noise frequency components. Based on these comparative results, an improved model for extracting inter-bundle, real life, coupling capacitances between SWCNT bundles has been proposed.
IEEE Transactions on Electron Devices, 2000
In this paper, the crosstalk problem for carbon nanotubes (CNTs) bundled interconnects is modeled in the framework of the multiconductor transmission line (MTL) theory by using a fluid description of the conduction phenomena in CNTs. Two two-port models for a two-line interconnect (one aggressor and one victim) are proposed. The first is based on the full-MTL equations coupling each CNT in the bundles. The second, which is a reduced order TL model coupling the CNT bundles, is derived from the first one and used for fast computations. The crosstalk models are used to study the impact on relevant electromagnetic performances of some actual technological and design aspects, such as the variability of the number of conducting CNTs in each bundle, their position in the cross section, the proximity of the signaling lines, the cross-sectional aspect ratio, and some advances in CNT manufacturing techniques. Both frequency-and timedomain characteristics are evaluated and compared with those of ideally scaled traditional copper interconnects. The results are compared with those obtained by simplified approaches, showing, in particular, that simple RC models may underestimate the crosstalk.
Crosstalk analysis in CNT bundle interconnects for VLSI application
IEEJ Transactions on Electrical and Electronic Engineering, 2014
Crosstalk noise voltage levels have been estimated at the far end of a victim line in capacitive coupled single-walled carbon nanotube (SWCNT) bundle interconnects under the influence of interconnect dimensions. The reported work on crosstalk analysis in SWCNT bundle interconnects to date have assumed the value of coupling capacitance as equivalent to the coupling effect between metal interconnects of same dimensions. In this paper, we propose an improved model to extract inter-bundle real-life coupling capacitances to fill that gap. A similar analysis is performed for a copper-based interconnect, and comparison is made with result obtained for CNT-based interconnect at 22-nm technology. SPICE simulation results reveal that the crosstalk noise voltage level at the far end of the victim line in CNT bundles is significantly lower than that in conventional metal (copper) conductors in three different cases, keeping the pitch fixed but varying the value of interconnect spacing and width.
Time-Domain Analysis of Coupled Carbon Nanotube Interconnects
Journal of Nanotechnology, 2014
This paper describes a new method for the analysis of coupling effects including the crosstalk effects between two driven coupled single-walled carbon nanotubes (SWCNTs) and the intertalk effects between two neighboring shells in a multiwalled carbon nanotube (MWCNT), based on transmission line circuit modeling. Using rigorous calculations, a new parametric transfer function has been obtained for the analysis of the impact of aggressor line on the victim line, which depends on the various coupling parameters such as the mutual inductance, the coupling capacitance, and the tunneling resistance. The influences of various parameters such as the contact resistance and the switching factor on the time behavior of coupling effects between the two coupled CNTs and an important effect named “crosstalk-induced delay” are studied and analyzed.
Microelectronics Reliability, 2015
This paper presents an accurate and efficient model for the transient analysis of multiwall carbon nanotubes (MWCNT) using finite-difference time-domain (FDTD) method. The proposed model can be essentially used to analyze the functional and dynamic crosstalk effects of coupled-two MWCNT interconnect lines. Using the proposed model the voltage and current can be accurately estimated at any point on the interconnect line and furthermore, the model can be extended to coupled-n interconnect lines with a low computational cost. Crosstalk induced propagation delay, peak voltage, and its timing instance are measured using the proposed model and validated by comparing it to the HSPICE simulations. Over a random number of test cases it is observed that the average error in estimating the noise peak voltage on a victim line is less than 1%. The proposed model is extremely useful for accurate estimation of crosstalk induced performance parameters of MWCNT interconnects.
Transient analysis of mixed carbon nanotube bundle interconnects
Electronics Letters, 2011
Presented for the first time is an accurate modelling hierarchy for mixed CNT bundle interconnects. Single-walled CNTs and multi-walled CNTs have been modelled as equivalent single conductor transmission lines and then combined to form a mixed CNT bundle interconnect, which is basically a multiple equivalent single conductor model. Two multiple equivalent single conductor interconnects have been taken to form the multiconductor transmission line model. The delays from transient analysis for both models for a unit bundle have been compared with the corresponding ones for SWCNT bundles and MWCNTs that exist in the literature. It is found that mixed CNT bundle interconnects are superior to both SWCNT bundle and MWCNT interconnects in terms of delay.
Stability analysis in multiwall carbon nanotube bundle interconnects
Microelectronics Reliability, 2012
Based on the transmission line model (TLM), we present an exact and general transfer function formula, useful for both single multiwall carbon nanotube (MWCNT) and MWCNT bundle interconnects. Using the standard parameters for 22-nm technology node we perform the Nyquist stability analysis, to investigate the dependence of the degree of relative stability for both single and bundle interconnects on the number of walls in each MWCNT its geometry and also on the bundle geometry. The numerical results, for 1-to 30-μm long interconnects composed of 3-to 7-wall-CNTs, show that by increasing the length or the outer shell diameter, both single and bundle interconnects become more stable. On the other hand, an increase in the number of walls, keeping the outer shell diameter constant, increases the relative stability of the single MWCNT and decreases that of the bundle interconnects. Furthermore, thermal conductivities of SWCNTs and MWCNTs are about 3 and 10 times 17 larger than those of Cu wires of similar dimensions [9, 10]. Moreover, tensile strengths of CNTs 18 are also two orders of magnitudes larger than that of Cu wires . While exact control of the MWCNT length and diameter and the preparation of MWCNT 20 samples with high purity is still a challenge, its fabrication processes for MWCNT-interconnects 21 is easier than that for . It is noteworthy that modeling for 22
Delay and crosstalk reliability issues in mixed MWCNT bundle interconnects
Microelectronics Reliability, 2014
Multi-walled carbon nanotube (MWCNT) bundles have potentially provided attractive solution in nanoscale VLSI interconnects. In current fabrication process, it is not trivial to grow a densely packed bundle having MWCNTs with similar number of shells. A realistic nanotube bundle, in fact, is a mixed CNT bundle consisting of MWCNTs of different diameters. This research paper presents an analytical model of mixed CNT bundle wherein MWCNTs having different number of shells are densely packed. Two different types of MWCNT bundles are presented: (1) MB that contains MWCNTs with similar number of shells (i.e., uniform diameters) and (2) MMB wherein MWCNTs having different number of shells (i.e., nonuniform diameters) are mixed. Multi-conductor transmission line theory is used to present an equivalent single-conductor (ESC) model of different MB and MMB configurations. Using the ESC model, performance is analyzed to address the effect of propagation delay, crosstalk and power dissipation that explores the reliability of an interconnect wire. It is observed that using an MMB arrangement, the overall reduction in delay and crosstalk are 15.33% and 29.59%, respectively, compared to the MB for almost similar power dissipation.