Electrical Cleaning of Rough Spherical and Bumpy Abrasive Particles Charged by Corona Ions in Post-CMP

This study describes electrostatic methods for effective post-CMP (Chemical Mechanical Polishing) cleaning of contaminated wafers with rough spherical and bumpy abrasive particles. The case when corona ions charged the particles was studied. The extended JKR adhesion model for rough surfaces was used in the analysis. Charges were uniformly distributed across the entire particle surface for the corona charging. Removal of charged rough spherical and bumpy particles was investigated. The electric fields necessary to detach alumina particles with different numbers of bumps, contact asperities, and charges from wafer surfaces with varying roughness levels were evaluated. The present model predictions were compared against experimental data for the detaching polystyrene latex particles from an aluminum oxide substrate. It was shown that the model predictions for the electric detachment fields agree with the corresponding experimental data for the selected range of parameters. The model provides an approach for removing rough spherical and bumpy particles charged by corona ions in diverse applications, including post-CMP cleaning.