Development of a Stimuli-Responsive Supramolecular Brush for Enhanced Post-CMP Cleaning

Abstract

With the miniaturization of device features, slurry chemistries have become increasingly complex and therefore require enhancement of current cleaning processes. Copper (Cu) chemical mechanical planarization (CMP), a critical process step in the fabrication of high-performance microprocessors, utilizes nanoparticle abrasives (i.e. SiO2) and functional chemistry (i.e. complexing agents, inhibitors, and pH adjusters) during the polishing process which can lead to contaminants on the wafer surface. Currently, post-CMP cleaning processes use a standard polyvinyl alcohol (PVA) brush coupled with functional cleaning chemistry to remove these contaminants, including organic residue, particle contaminants, and excess ions. With stringent contaminant-free demands, it is crucial to develop cleaning consumable sets to meet these demands. This work focuses on the functionalization of PVA with supramolecular moieties to enhance the removal of nanoparticle and organic residue. Results have shown that the addition of supramolecular complexes to the PVA brush enhanced particle removal through hydrophobic/hydrophilic interactions at the brush/wafer interface. Additionally, this functionalized PVA brush shows increased adsorption of metal ions (specifically Cu2+) via inclusion complexes. Initial results have also shown that PVA containing pore forming additives have a photochemical response in which when irradiated with specific wavelengths of light the brush can be turned “on” or “off” based on chemical interactions at the brush/wafer interface.