The removal of 10-nm contaminant particles from micron-scale trenches using CO₂ nano bullets

The removal of nano-sized contaminant particles (CPs) from trenches formed on Si wafer is an important issue in the semiconductor industry. The particle beam technique, which is an advanced aerosol cleaning technique using nano-sized bullet particles (BPs) shot at supersonic velocity, has successfully cleaned CPs on flat surfaces down to 10 nm. In this paper, the same technique was applied to the removal of 10 nm Al₂O₃ particles from micron-scale trenches using CO₂ nano bullets. Trenches of 4, 10, and 20 μm depth were fabricated at 2 μm and 50 μm widths, with a maximum aspect ratio of 10. When nano-sized bullets were shot into the contaminated trenches, 10 nm contaminants deposited on the side walls, bottom surfaces, and corners were completely removed from a variety of trenches in just a few seconds. Cleaning efficiency greater than 95 % was attained. Size and velocity of the BPs were the important parameters affecting removal of CPs in the 10 nm size range from micron-scale trenches.