Abstract To reduce the intrinsic resistance-capacitance delay of back-end-of-line (BEOL) interconnects in integrated circuits, low-dielectric-constant (low-k) materials with a dielectric constant (k)

Comparison of Various Low Dielectric Constant Materials

Triangular cross-sectioned carbon nanotube (CNT) bundle interconnects have gained attention recently due to their inherent advantage of least electrostatic coupling and hence reduced crosstalk. Moreover, this technology is in tune with the idea of miniaturization of components in integrated circuits. For the first time, this paper analyses and discusses the crosstalk behaviour of triangular CNT bundle interconnects in two-line and three-line configurations. First, the equivalent circuit model of the triangular CNT bundle is presented. Resistance, capacitance and inductance values are calculated for 20 nm and 14 nm technology nodes. CNTFET-based drivers and loads are connected to the interconnects. Performance analysis of triangular CNT bundles with respect to traditionally proposed square CNT bundles is done. The performance metrics that determine the functionality of the interconnects such as propagation delay, power dissipation, crosstalk-induced delay and dynamic power dissipation, are found by HSPICE simulations. Results show that both square and triangular CNT bundles suffer from crosstalk and of the two, triangular CNT bundles perform better than square CNT bundles.

Crosstalk Analysis of Triangular CNT Bundle Interconnects

The capacitance of the interconnect, which contributes to RC delay, power, and crosstalk, is increasingly limiting the performance of ULSI chips as IC technology advances. Different dielectric materials are employed as electrical shielding between interconnects (also called as inter-wire dielectrics) to minimise the coupling capacitance of closely spaced interconnects, and they are compared in terms of their performance. For SWCNT and MWCNT interconnects at various global interconnect lengths for 20 nm and 14 nm technology nodes, performance parameters such as crosstalk delay, power dissipation, power crosstalk delay product (PCDP) and crosstalk noise are calculated and compared. It is observed that, upon using different dielectric materials in CNT bundle interconnect, MWCNT bundle interconnects is performing better compared to SWCNT bundle interconnects at 20 nm and 14 nm technology nodes for all global interconnect lengths. 

Performance Analysis of CNT Bundle Interconnects in Various Low-k Dielectric Media

Optimal repeater insertion is important in VLSI interconnects to reduce their propagation delay and power dissipation. We propose a particle swarm optimization (PSO) based optimal repeater number for different lengths of carbon nanotube (CNT) interconnects at 22nm and 14nm technology nodes. First, numerical equations for optimal repeaters are modelled. Secondly, a PSO based algorithm is developed and various input parameters are enlisted to train the PSO. Optimal number of repeaters and the propagation delay for CNT interconnects for lengths ranging from 500 to 2000µm are found out. Results are compared for both the methods and it is found that they are within 2% deviation. This means that PSO is an effective method to find optimum repeaters in VLSI interconnects. Though earlier works show similar findings, we have used CNTFET based inverters as drivers of CNT interconnects for the first time. Also, for two values of repeater size, i.e., h = 50 and 75, we have carried out the analysis.

A PSO based optimal repeater insertion technique for Carbon Nanotube interconnects

Frequency Response Analysis of CNT Bundle Interconnects

Signal reliability of nano-scale interconnects is a major cause of concern at subthreshold voltages. This paper deals with the subthreshold operation of carbon nanotube (CNT) bundle interconnects o...

Waveform analysis of carbon nanotube interconnects connected to various driver/load circuits

This paper proposes the use of triangular cross-sectioned CNT (T-CNT) bundle interconnects for VLSI circuits. The geometry of T-CNT bundles has the advantage of offering least possible crosstalk between adjacent interconnects. The performance factors like propagation delay, power dissipated, crosstalk delay, crosstalk power, On/OFF time of the output waveforms and the output waveform swing are analyzed and compared with traditionally used square CNT (S-CNT) bundle interconnects. Results show that T-CNT bundles offer lesser power dissipation at longer lengths >1000 µm. Also the crosstalk delay is lesser for T-CNT bundles compared to S-CNT bundles. Both the types of interconnects are driven by GAA CNTFET based inverter circuits.

Performance Analysis of Square and Triangular CNT Bundle Interconnects Driven by CNTFET-Based Inverters

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.

Ananyo Banerjee

Papers

Waveform analysis of carbon nanotube interconnects connected to various driver/load circuits

Performance Analysis of Square and Triangular CNT Bundle Interconnects Driven by CNTFET-Based Inverters

On the Applicability of Triangular Carbon Nanotube Bundles as VLSI interconnects