Particle removal behavior of composite surfactants during the post-CMP cleaning process for Co-patterned wafers

<!-- START_ABSTRACT --> <p> Cobalt (Co) with its low resistivity, superior adhesion property, and void-free seamless fill ability pledges to transform the landscape of integrated circuits in many areas, especially in interconnects and logic contacts. The cleaning of Co surfaces after chemical mechanical polishing (CMP) is an indispensable step, as the process can introduce defects such as SiO2 nanoparticles, organic residues, and severe corrosion. Based on preliminary investigations, this study proposes a composite system utilizing a cationic surfactant combined with a nonionic surfactant. Specifically designed for post-CMP cleaning of Co patterned wafers, the system addresses the issues of low particle removal efficiency (PRE) associated with single surfactant approaches. The cleaning performance of this system was validated for the first time on actual Co patterned wafers (94.58 % PRE), which is significantly superior to that of individual surfactant systems. Contact angle measurements demonstrate that the introduction of composite surfactants enhances the wettability of the cleaning solution, mitigating the hydrophobicity of the Co surface induced by corrosion inhibitors. Furthermore, zeta potential measurements and analysis of electrostatic interactions indicate that under the influence of the complex surfactant, stronger repulsion occurs between silica particles and the Co surface, facilitating effective particle cleaning. Quantum chemical calculations further elucidate the efficacy of surfactants, with hydrophilic groups serving as primary adsorption sites. This study addresses the current gap in cleaning research, which has been largely confined to blanket wafers, and provides valuable insights for practical Co post‑CMP cleaning solutions. </p> <!-- END_ABSTRACT --> <!-- START_TEMPLATE --> <ul> <li> Source: </li> <li> Tags: </li> </ul> <!-- END_TEMPLATE -->