Analysis of the optic/impurity-particle/pad interaction for reduction of scratches formed on optics during pad polishing

• We developed a model for interactions of a single large impurity particle with the optic and pad during pad-polishing.
• Equations are provided for calculating the normal load applied on the optic by the impurity particle.
• Initiation and evolution of the scratches under the combined effects of the normal and frictional forces are illustrated.

A model for interactions of a single large impurity particle with the optic and pad during pad-polishing has been developed to detailedly illustrate the scratch formation process. Equations for calculating the normal load applied on the optic by the impurity particle are provided, and the friction between the optic and impurity particle has also been considered in scratch formation. Initiation and evolution of the scratches under the combined effects of the normal and friction forces are illustrated in the model. The most important factors affecting the normal load and thus scratch formation have been analyzed and verified using published experimental results. Based on the model, the implications in reduction of scratch formed on optics during pad polishing have been analyzed.