摘要
The continuous scaling of integrated circuits (ICs) necessitates the downscaling of interconnect dimensions, particularly within the back-end-of-line (BEOL) structures. However, this miniaturization exacerbates the contribution of surface scattering to metal resistivity, posing a significant challenge to maintaining device performance. To address this issue, this work investigates the application of self-assembled monolayers (SAMs) with ultrathin thicknesses (1–2 nm) as multifunctional interfacial layers on dielectric substrates. These SAMs serve the dual purpose of mitigating electron scattering at the metal/dielectric interface and functioning as ultrathin diffusion barriers for next-generation interconnect technologies. Conventional diffusion barriers, such as Ta/TiN, have been widely adopted due to their effective barrier and adhesion properties. Nevertheless, as the dimensions of vias and metal lines continue to shrink, the relative thickness of these traditional barriers consumes a substantial fraction of the available cross-sectional area, ultimately leading to a rise in electrical resistance. Considering this limitation, SAMs offer a promising alternative, enabling the formation of molecularly thin barriers while preserving the available space for conductive metal.This study focuses on the design and implementation of arylimine-functionalized silane SAMs, specifically benzyliminetriethoxysilane (BITES) and 2-hydroxybenzyliminetriethoxysilane (2-HBITES). These tailored SAMs not only enhance adhesion to silicon-based dielectrics but also promote specular electron scattering, which becomes increasingly critical as metal line dimensions decrease. In this work, we extend our investigation to the 2-HBITES SAM, which exhibits a notable two-fold improvement in ruthenium (Ru) complexation compared to its BITES counterpart. The stronger SAM–Ru interaction achieved with 2-HBITES significantly enhances both the diffusion barrier characteristics and interfacial adhesion when benchmarked against methyl-terminated and BITES-functionalized silane surfaces. Remarkably, the introduction of the hydroxyl-modified arylimine group in 2-HBITES results in a four-fold improvement in adhesion strength and substantially enhances the thermal and diffusion barrier properties. The Ru/2-HBITES/SiO₂ interconnect structure demonstrates an increase of at least 100 °C in breakdown temperature relative to the Ru/SiO₂ baseline, indicating superior thermal robustness and interfacial stability. Moreover, this paper presents our latest findings on the thermal reliability of SAMs within a sandwiched metal/SAM/dielectric architecture—a configuration that has received limited attention to date. The insights gained from this study provide a foundation for the development of scalable, ultrathin diffusion barriers and adhesion layers essential for advancing future interconnect technology. Figure 1