Mechanism Analysis of Nanoparticle Removal Induced by the Marangoni-driven Flow in Post-CMP Cleaning

Wafer drying induced by Marangoni effect is crucial to achieving an ultraclean surface in integrated circuit manufacturing. According to the previous opinions, the entrained water film on wafer surface was stripped by Marangoni effect, and thus the watermark defect induced by evaporation was inhibited. However, the influence of particle removal induced by Marangoni effect on the ultraclean surface preparation is lack of adequate understanding. The present work implements an experimental and numerical investigation of wafer cleaning behavior engendered by Marangoni effect during the wafer withdrawn process. The impacts of critical process parameters and substrate properties on the particle removal efficiency are systematically studied. The results show that Marangoni effect has better cleaning performance on the glass substrate compared with that of silicon and copper. The numerical simulation indicates that the Marangoni effect is more dramatic on glass substrate owing to the better wettability. Furthermore, the stress analysis reveals the adsorption force of fluorescent particle on the copper surface is stronger than that of silicon and glass. Therefore, particle cleaning on the copper surface is much more difficult. The investigation of cleaning performance driven by the Marangoni effect will contribute to a comprehensive understanding of the mechanism of ultraclean surface preparation.