Effect of solvent film and zeta potential on interfacial interactions during optical glass polishing.

Abstract

The deployment of polishing slurry is one of the important research topics in the field of chemical-mechanical polishing. It is expected that technological breakthroughs in this process will lead to an improvement of the surface quality of fabricated optical components. In this investigation, we added several types of electrolytes into cerium oxide polishing slurries and evaluated their influence on the material removal rate (MRR) and surface roughness (Sa) during K9 glass polishing. Furthermore, we investigated their influence on the zeta potential, particle size distribution, and suspension stability of the slurries. The results show that the introduction of an electrolyte into the polishing slurry changes not only the zeta potential of the ceria particle surface, but also the type and thickness of the deposited solvent film. The presence of a hydrophilic solvent film results in repulsion between individual particles and between the particles and the glass surface. However, a hydrophobic solvent film enhances the attraction between individual particles and between the particles and the glass surface. Moreover, thicker solvation films correspond to a greater force. This has a great impact on the interfacial interaction between the particles and the glass surface during the polishing process. The presence of the hydrophobic solvent film results in a high MRR, while the hydrophilic solvent film is associated with low Sa. In this paper, the interaction mechanisms of the abrasive particles and the glass interface during the polishing process are elucidated by considering the zeta potential and the solvent film type. In addition, a method for reducing the resulting Sa after glass polishing is proposed.