Potential- and Convection-Dependent Synergistic Coadsorption of Electroplating Additives for Vias Copper Interconnection Evidenced by Shell-Isolated Nanoparticle-Enhanced Raman Spectroscopy.

Metal interconnection in integrated circuits (IC) is often obtained with electroplating copper in the high-aspect micronano vias. Electroplating additives are crucial for the void-free filling in order to overcome the nonuniform potential distribution and insufficient mass transfer inside the high-aspect micronano vias. However, revealing the molecular action mechanism of the additive is hindered for conventional spectroscopy techniques such as Raman spectroscopy due to the low operando concentration of these additives. Surface-enhanced Raman techniques such as shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS) have shown promising results of revealing the interfacial adsorption behavior of a single additive. Here, an improved SHINERS configuration with a spectroelectrochemical flow cell and a water immersion objective is developed to obtain the in situ molecular information on the potential and convection dependent coadsorption of multiple coexisting additives in a novel acid copper sulfate electroplating solution. The results present a valuable in situ instrumental method to investigate the molecular action mechanism of electroplating additives.