Interaction Forces Between a Glass Surface and Silica-Modified PMMA-Based Abrasives for CMP Measured by Colloidal AFM

Abstract

Interaction forces between a glass surface and two types of silica-coated poly(methyl methacrylate) (PMMA)-based terpolymer abrasive particles were investigated using colloidal atomic force microscopy (AFM) and correlated with relevant chemical mechanical planarization (CMP) and post-CMP parameters. Based on the average values of the pull-off force vs pH, the interaction between a glass bead and the composites can be considered as a silica-glass interaction, as confirmed by ζ potential measurements. The increase in repulsive force with increasing pH corresponds to a decrease in composite-glass adhesion. For pH between 2 and 7, the electrostatic attractive forces between polymer particles and silica surface are responsible for high particle counts.