Mitigation of Electromigration in Metal Interconnects via Hexagonal Boron Nitride as an Ångström‐Thin Passivation Layer

Abstract

Electromigration in metal interconnects remains a significant challenge in the continued scaling of integrated circuits towards ever‐smaller single‐nanometer nodes. Conventional damascene architectures of barrier/liner layers and conducting metal cause inevitable compromises between device performance and feature dimensions. In contrast to contemporary barrier/liner materials (e.g., Co, Ta, and Ru), an ultrathin passivation layer that can effectively mitigate electromigration is needed. At the ultimate atomically‐thin limit, 2D materials are promising candidates given their exceptional mechanical properties and impermeability. Here, a facile and effective approach is presented to mitigating electromigration in copper (Cu) interconnects via passivation with insulating monolayer 2D hexagonal boron nitride (hBN). The hBN‐passivated Cu interconnects, compared to otherwise identical but bare Cu interconnects, exhibit on average a >20% higher breakdown current density and a >2600% longer lifetime (at a high current density of 5.4 × 107 A cm−2). Post‐mortem metrology elucidates uniform conformal contact between the hBN‐passivated Cu interface and common failure features due to electromigration.

Electromigration-Induced Evolution of Micromorphology and Electrical Properties in Gold Nanowires: Implications for Nanoelectronics

“…Prior research has noted that the deposition of an insulating layer (such as SiO 2 or BN) onto the metal interconnect’s surface significantly impedes atomic diffusion along the surface. This hindrance, in turn, suppresses electromigration, mitigating hillock formation. , Conversely, conductors lacking an oxide film exhibit noticeable electromigration . These experiments underscore the role of the nanowire surface as a conduit for atomic diffusion.…”

“…This hindrance, in turn, suppresses electromigration, mitigating hillock formation. 53,54 Conversely, conductors lacking an oxide film exhibit noticeable electromigration. 55 These experiments underscore the role of the nanowire surface as a conduit for atomic diffusion.…”

Application-driven synthesis and characterization of hexagonal boron nitride deposited on metals and carbon nanotubes

“…The unique characteristics of h-BN have made it demonstratively useful as the gate dielectric in 2D field effect transistor [11], substrate and encapsulant for record high velocity saturation in graphene [12], passivation layer to protect air-sensitive materials as well as prevent electromigration [13,14], and substrate for heat spreading [15]. While mechanical exfoliation from a bulk crystal can yield micronsized h-BN flakes for proof-of-concept experiments, large area, continuous h-BN films are necessary for practical applications.…”

Enhancement of Electromigration Reliability of Electroless-Plated Nanoscaled Copper Interconnects by Complete Encapsulation of a 1 nm-Thin Self-Assembled Monolayer

“…[5][6][7] Moreover, electromigration in metal interconnect lines remains a significant challenge in the continuous downscaling of integrated circuits. Indeed, recent studies have used two-layer graphene to passivate the sidewall and top of Cu interconnects; 8 monolayers of boron nitride 9 and polyimide 10 have recently been used to encapsulate Cu interconnects and Cu redistribution lines, respectively. These studies show that the EM reliability of the Cu interconnect lines is markedly enhanced.…”

“…It is promising to enhance EM reliability of Cu interconnects by encapsulating ultrathin layers of two-dimensional graphene 8 or boron nitride. 9 However, the effect of molecularly thick SAM's encapsulation on influencing EM reliability of metal interconnect lines is unclear and lack of study. We have recently developed an allwet, electroless gap-filling process using an SAM of (3-aminopropyl)trimethoxysilane (APTMS) as liner/barrier and seed linker.…”