Influence of additive coadsorption on copper superfill behavior

The interaction between the additive components chloride, accelerator, and suppressor is the focus of the present paper. Based on Frumkin and Damaskin's adsorption theory, an advanced concept for the superfilling mechanism is introduced. Cyclovoltammetry measurements show the additive impact on the current-potential behavior and their synergetic effect on the charge transfer across the electrode-electrolyte interface. The measurements are supported by partial fill experiments. Cross-section scanning electron microscopy micrographs reveal that the synergetic impact of an accelerator and a suppressor is very different from their individual contributions. Chloride ions support the adsorption of suppressor molecules, while the accelerator enhances the desorption of the suppressor molecules from the copper surface. The higher the local accelerator concentration in an electrolyte, the more suppressor molecules desorb from the surface. The synergetic behavior between the chloride, suppressor, and accelerator can be explained by coadsorption, which is an important key in the process of copper superfilling.