摘要
The miniaturization of integrated circuits (ICs) necessitates alternative diffusion barriers with reduced electrical resistance to mitigate the RC delay effect. Self-assembled monolayers (SAMs), with their molecular-scale thickness (1-2 nm), offer a promising solution for controlling Ru interdiffusion while preserving low resistivity. This study investigates the effectiveness of 2-hydroxybenzylimine-triethoxysilane (2-HBITES), benzyliminetriethoxysilane (BITES), and n-octyltriethoxysilane (OTS) as SAM-based diffusion barriers for Ru metallization. SAM functionalization was confirmed using X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS), while barrier performance was evaluated through sheet resistance measurements, X-ray diffraction (XRD), transmission electron microscopy (TEM), and scanning transmission electron microscopy (STEM) following rapid thermal annealing (RTA). The results demonstrate that SAM-modified substrates effectively suppress Ru silicide formation, with 2-HBITES exhibiting the highest thermal stability, delaying Ru interdiffusion until 800 degrees C, compared to 775 degrees C for BITES, 725 degrees C for OTS, and 600 degrees C for non-functionalized Ru/Ox/Si. The superior performance of 2-HBITES is attributed to its salicylaldimine terminal group, which enhances Ru adhesion and diffusion suppression. Additionally, this study provides direct XPS evidence of SAM retention within a Ru/SAM/Ox/Si structure post-annealing at 700 degrees C, highlighting the potential of SAMs as thermally stable, ultrathin diffusion barriers for advanced interconnect technologies.