Chemical mechanical polishing by colloidal silica-based slurry for micro-scratch reduction

The chemical mechanical polishing (CMP) of aluminum and photoresist using colloidal silica-based slurry was investigated. The effects of varying slurry pH, silica concentration and oxidizer concentration on surface roughness and removal rate were investigated in order to determine the optimum conditions for those parameters. Using these optimum conditions silica-based CMP was compared with conventional CMP, which uses an alumina-based slurry. The results of the CMP of the aluminum with the colloidal silica-based slurry were good, but the CMP of the photoresist were not. The colloidal-based silica slurry produced a desirable fine Al surface with few micro-scratches, which is similar to what is produced by CMP using a filtered alumina-based slurry, but produced a photoresist surface with many micro-scratches.