International Technology Roadmap for Semiconductors 2003の要求清浄度について － シリコンウエハ表面と雰囲気環境に要求される清浄度, 分析方法の現状について －

Mixed carbon nanotube bundles (MCBs) are considered to be highly potential interconnect solutions in the current nanoscale regime. Different MCBs with random and spatial arrangements are proposed based on the placements of single- and multiwalled carbon nanotubes (CNTs) (SWNTs and MWNTs) in a bundle. Propagation delay and dynamic crosstalk performances are analyzed using the modified equivalent single conductor model of proposed MCB topologies. Encouragingly, a significant reduction in propagation delay and crosstalk delay is observed for a spatial arrangement of an MCB wherein MWNTs are placed peripherally to the centrally located SWNTs. Typically, the average delay with and without crosstalk is improved by 82.8% and 80%, respectively, compared to the MCB having randomly distributed SWNTs and MWNTs.

Analysis of Delay and Dynamic Crosstalk in Bundled Carbon Nanotube Interconnects

This study presents an efficient geometry for active shielding of multiwalled carbon nanotube (MWCNT) bundle interconnects which cancels the crosstalk-induced functional failures in ternary logic. In this geometry, MWCNT bundles are used innovatively as shields on both sides of the signal transmission line to reduce the crosstalk effects while maintaining the minimum interconnect pitch. Simulations are performed using HSPICE for intermediate and global interconnects in ternary logic at 14-nm node. The results indicate that the crosstalk-induced functional failure in ternary logic is omitted by using the proposed structure. Moreover, according to the results, our proposed geometry reduces the crosstalk noise peak as compared to the widened MWCNT bundles, distanced MWCNT bundles and Cu interconnects on average by 41%, 44%, and 61% for the intermediate interconnects and 61%, 46%, and 74% for the global interconnects, respectively, without any considerable power consumption penalties.

Active Shielding of MWCNT Bundle Interconnects: An Efficient Approach to Cancellation of Crosstalk-Induced Functional Failures in Ternary Logic

Magmatic and metamorphic imprints in 2.9 Ga chromitites from the Sittampundi layered complex, Tamil Nadu, India

The mafic and ultramafic rocks of Mettupalayam belong to Southern Granulite Terrain (SGT), and it is prominent with economically valuable resources. The radiation shielding properties of the rock types, along with the remote sensing aspects, are considered in the study. The image processing techniques like Principal Component Analysis, Band ratio, Minimum Noise Fraction are performed using Landsat data to discriminate the litho units. The spectral characters derived from Landsat data identified with the significant absorptions of Fe2+, Fe3+and OPx. The Monte Carlo simulation was applied to evaluate the radiation protection ability of the studied rock samples. The examination showed a high shielding capacity for Gabbro rocks compared to the other studied rocks. The linear attenuation coefficient of the mentioned Gabbro rocks varied among 47.838 and 0.075 cm−1 when the gamma-ray energy increases in the energy interval 0.015 and 15 MeV. Moreover, the Radiation defensive capacity of the Gabbro samples decreased from 100 to 20.095% while the halve value layer increases from 0.014 to 9.269 cm with raising the gamma photon energy among 0.015 and 15 MeV, correspondingly. 

Applicability of the multispectral remote sensing on determining the natural rock complexes distribution and their evaluability on the radiation protection applications

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.

Role of Semiconducting Carbon Nanotubes in Crosstalk Reduction of CNT Interconnects

Interconnects plays an important role in integrated circuits. Copper is used as an interconnect material, but beyond 22nm technology node it faces many problems due to grain boundary scattering, and therefore carbon nanotubes are the most promising future interconnect materials. Various techniques and approaches such as driver sizing, repeater sizing, repeater insertion, wire sizing, wire spacing, shielding, boos table repeater were used by various researchers. Many of these techniques can be utilized for future CNT based VLSI interconnects as well. This paper presents a detailed discussion on the techniques and approaches of past, present and future relevant for interconnects of VLSI circuits.

Optimization Techniques for CNT Based VLSI Interconnects — A Review

In this paper, we propose transmission gates (TGs) as buffers/repeaters for carbon nanotube (CNT)-based VLSI interconnects. Various performance metrics of the TG buffer, viz. propagation delay, crosstalk-induced delay, power dissipation, and power-delay product under super-threshold and sub-threshold conditions are analysed. Performance analysis of TG buffers with CMOS inverter buffers at various interconnect lengths and buffer insertion intervals is done. We have also analysed the performance of Single-wall carbon nanotube (SWCNT) bundle and three different configurations of mixed CNT bundles. By comparing the power-delay product of both the buffers, it is found that TG buffers are more suitable for applications in CNT-based integrated circuits.

Transmission Gate as Buffer for Carbon-Nanotube-Based VLSI Interconnects

This paper investigates the multi equivalent single conductor (MESC) model for mixed CNT bundles (MCBs) which contains metallic single and double walled CNTs at the core and semiconducting single walled CNTs at the periphery. This structure shows the least delay due to crosstalk.

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Reduction of crosstalk in mixed CNT bundle interconnects for high frequency 3D ICs and SoCs

This paper proposes a repeater for boosting the speed of interconnects with low power dissipation. We have designed and implemented at 45 and 32 nm technology nodes. Delay and power dissipation performances are analyzed for various voltage levels at these technology nodes using Spice simulations. A significant reduction in delay and power dissipation are observed compared to a conventional repeater. The results show that the proposed high-speed low-power repeater has a reduced delay for higher load capacitance. The proposed repeater is also compared with LPTG CMOS repeater, and the results shows that the proposed repeater has reduced delay. The proposed repeater can be suitable for high-speed global interconnects and has the capacity to drive large loads.

A. Karthikeyan

Papers

Role of Semiconducting Carbon Nanotubes in Crosstalk Reduction of CNT Interconnects

Optimization Techniques for CNT Based VLSI Interconnects — A Review

Transmission Gate as Buffer for Carbon-Nanotube-Based VLSI Interconnects

Reduction of crosstalk in mixed CNT bundle interconnects for high frequency 3D ICs and SoCs

High-speed and low-power repeater for VLSI interconnects