Sub-100 nm² Cobalt Interconnects

Resistivity scaling and electron surface scattering in epitaxial Co(0001) layers

“…This value is 82% larger than that for Cu 42 and 21% larger and 30% smaller than that for W(011) and W(001), respectively. 26 Based on this comparison and the simple model described in the introduction that assumes metal-independent surface and grain boundary scattering coefficients, the line resistances for Co and W are expected to be approximately equal for any given wire width w, because the ρo×λ products and ρo values are similar for Co and W, but are larger than that of Cu for all w. Nevertheless, Co lines may exhibit a conductance advantage over W because (1) we measure a high specularity (p = 0.55 ± 0.05) at the Co-vacuum interface, while the reported p = 0 for W, 11,26 suggesting that Co has a higher chance than W to exhibit partially specular surface scattering with a suitable barrier/liner material, and (2) Co is expected 73 to have a lower grain boundary reflection coefficient R, based on the measured range R = 0.07-0.6 for Co, [46][47][48][49]74 and R = 0.4-0.67 for W, 11,14,75 and (3) Cobalt has a higher potential for grain growth and defect removal through annealing, because of its 52% lower melting point in comparison to W.…”

Optimal repeater insertion for horizontal and vertical graphene nanoribbon interconnects

“…To cope with such issues, alternative conductive materials with low resistivity and high ampacity are highly required for interconnect applications . Graphene, a two‐dimensional carbon material with a honeycomb lattice, has been proposed as a promising interconnect material in future nanoscale integrated circuits (ICs) .…”

“…2 To cope with such issues, alternative conductive materials with low resistivity and high ampacity are highly required for interconnect applications. [3][4][5][6] Graphene, a two-dimensional carbon material with a honeycomb lattice, has been proposed as a promising interconnect material in future nanoscale integrated circuits (ICs). 7 To reduce large resistance of a monolayer graphene nanoribbon (GNR), multilayer GNR has been demonstrated to be superior to their Cu counterparts for intermediate and global level interconnect applications.…”

Demonstration of CMOS-Compatible Multi-Level Graphene Interconnects With Metal Vias

“…(a) Resistance per unit length versus wire width for Cu, Co, and Ru wires by single damascene process, and Co and DMLG wires by SE, with AR of 1 and 2. The Cu, Co, and Ru wire resistance by damascene process is estimated from an empirical model [6], Co wire resistance by SE is estimated from the model in [7], and DMLG wire resistance is calculated from an analytical model based on the Landauer approach [8] with consideration of DMLG bandgap opening (for sub-20 nm wire widths) and a doping level of |E F | = 0.6 eV. All the models are calibrated with measured data.…”

“…In addition, it simplifies the backend-of-line (BEOL) fabrication by eliminating low-k dielectric etching, which can potentially increase the dielectric constant because of plasma damage, and thereby affect the circuit performance [21], [22]. Even though reliability/performance of horizontal wires by SE process for both metals [21], [7] and DMLG [19], [20] are well studied, realization and characterization of a multi-tier graphene interconnect system by SE incorporating robust and low resistance vias/contacts have remained elusive. Vias are crucial elements for signal propagation between various metallization levels, which also suffer from significant EM at advanced technology nodes [23], as also shown in detail in Section II-B.…”