Mapping Surface Chemistry During Superfilling with Shell-Isolated Nanoparticle Enhanced Raman Spectroscopy and X-ray Photoelectron Spectroscopy

Abstract

Silica shell-isolated Au nanoparticles are used as reporters for shell-isolated nanoparticle enhanced Raman spectroscopy (SHINERS) measurements to track and map the coverage and state of surfactant additives during electrochemical deposition. The propensity of a sub-monolayer coverage of Au@SiO2−x nanoparticles to remain segregated on advancing surfaces during Cu Damascene electrodeposition is demonstrated including enrichment (dilution) on concave (convex) surface segments. The local coverage of sulfonate-terminated disulfide (SPS) and/or thiolate (MPS) accelerator and co-adsorbed chloride is mapped during superconformal deposition on SPS-derivatized trench patterned arrays. Comparison with Cu deposition on nanoparticle-free regions indicate that for sub-monolayer coverages the Au@SiO2−x nanoparticles do not hinder the essential SPS/MPS adsorbate and metal deposition dynamics responsible for trench superfilling. X-ray photoelectron spectroscopy (XPS) studies on nanoparticle-free specimens reveal similar quantitative trends in SPS/MPS adsorbate coverage during metal deposition congruent with the effect of area change as detailed by the curvature enhanced accelerator mechanism (CEAC). SHINERS provides a powerful means for investigating the molecular details of superfilling and, more generally, surfactant mediated growth.