Improving selectivity on germanium CMP applications

Abstract

In the presented paper, the adsorption characteristics of cationic and anionic surfactants on germanium and silica were studied in order to improve selectivity in germanium based shallow trench isolation chemical mechanical planarization applications. It was observed that the very strong or loose self-assembled surfactant structures can help obtain selectivity on the silica/germanium systems. Simultaneously, good defectivity control with a sufficient material removal rate was obtained. The surface charges manipulated by the surfactant adsorption and the hydrophobic nature of the germanium surface were main criteria on the selection of the proper surfactant/oxidizer system. In addition, impact of surfactant addition on particle-particle interactions controlling slurry stability was also investigated in the paper.