Analysis of Multilayer Graphene Nanoribbon Interconnects Constrained by Structural Edge Roughness and Corrugated Surface Dielectric

Abstract

which can further degrade the interconnect performance. Hence, the increase in resistivity due to scaling is further aggravated by rough surfaces of Cu interconnect. [5,6] As a result of the issues faced by conventional Cu interconnects, researchers are on a quest to find a suitable candidate for very large scale integration (VLSI) on-chip interconnects. Cu-based materials like Cu-carbon nanotube (Cu-CNT) composite, [7] Cu-Graphene hybrid, [8] and Cu-Carbon hybrid [9] have been proposed as possible substitutes for Cu interconnects. Although, it is worth noting that the related fabrication of Cubased materials faces many challenges like achieving uniform CNT-Cu distribution, compatibility with complementary metal oxide semiconductor (CMOS) technology, and lack of a fully developed fabrication process. [7][8][9] In recent years, 1D carbonbased nanomaterials like CNTs and graphene nanoribbons (GNRs) are of significant interest in various applications like electronic devices, VLSI on-chip interconnects, through silicon via (TSVs) for 3D ICs, sensors, optics, medicine, mechanics, spintronics and energy storage devices, owing to their exceptional electronic, optical, thermal, and mechanical properties. [10][11][12] Moreover, both GNRs and CNTs show higher current densities, electrical and thermal conductivities than Cu. [13] Hence, researchers proposed GNRs and CNTs as emerging alternatives to conventional Cu for VLSI on-chip interconnects. [13][14][15][16] GNRs having planar structures are more consistent with the semiconductor industry's fabrication technology, [17,18] making GNRs preferable to CNTs.GNRs are classified into single-layer (SLGNR) and multilayer (MLGNR) GNR, where SLGNR with a single layer of GNR has very high intrinsic resistance. Hence, to achieve lower resistance and better performance, MLGNR is proposed in which multiple GNR layers are stacked on top of one another. [19,20] The MLGNRs can be further classified based on the contact formed between metal and MLGNR, i.e., top-contact (TC-MLGNR) and side-contact (SC-MLGNR) MLGNR. SC-MLGNR has lower resistance as all the layers are physically coupled to metal contacts, whereas only the topmost layer forms a connection with the metal contact in TC-MLGNR, leading to its inferior performance. However, in the present scenario, fabrication of TC-MLGNR is less challenging and practically feasible than SC-MLGNR. [19,20] TC-MLGNRs

Delay characterization of multilayer graphene nanoribbon interconnects in presence of scattering and thermal effects

“…Under in‐phase switching conditions for coupled configuration of interconnects (Figure 7), victim net and both the aggressor nets switch simultaneously in same phase. For example, when the victim net switches from logic 0 → 1, at the same time the aggressor nets are switched from logic 0 → 1 or vice‐versa 27 …”

“…The p.u.l. c m , C q ( T ) and C e of GNR are given as 24,27 : …”

“…Equation (7) is used to calculate Λ eff,1 ( T ) for the MCNT bundle, where λ AC ( T ) and / are obtained from References 12,36. Also, Λ eff,2 ( T ) for MCNT bundle is obtained using modified Equation (8), that is, 27,36 From D‐MLGNR point of view, prospective intercalation dopants viz. AsF 5 , FeCl 3 , and Li are employed to improve fermi level and in‐plane conductivity of HTC‐MLGNR.…”

“…In this subsection, the dynamic XT-D at the far end of the victim net, considering all the variants of Cu and MLGNR interconnects, are evaluated and discussed under in-phase switching conditions to observe the impact on critical timing issue of the signal propagating in VLSI interconnects. 27 Under in-phase switching conditions for coupled configuration of interconnects (Figure 7), victim net and both the aggressor nets switch simultaneously in same phase. For example, when the victim net switches from logic 0 !…”

“…HTC, HSC, and VTC) and D‐HTC‐MLGNR are discussed. Figure 1 shows cross‐section view of three adjacent capacitively coupled victim and aggressor nets, with thickness t , width w , spacing s, and coupling capacitance ( C c ), each one placed at a distance Y ILD from the upper and lower ground plane 21,26,27 …”