Removing 20 nm PSL Particles Using a Supersonic Nano-particle Beam

Abstract

Cryogenic particle beam is an effective means of removing nano-sized contaminant particles from a substrate. Based on the previous finding that a smaller bullet size and a higher velocity are more effective for removing contaminant particles with a higher adhesion pressure, a new technique of generating bullet particle beam with novel properties required for removing polystyrene latex (PSL) particles - smaller particle size moving at a higher velocity - was developed, using Ar/He mixture gas and a Laval nozzle of special design. Particles of 10 nm size range - smaller by a factor of 100 than the conventional argon aerosols were successfully generated. Particles generated at optimum pressure and temperature conditions could perfectly remove PSL particles down to 20 nm. Unlike the case of ceramic particles, cleaning performance was found to be dependent on the direction of wafer surface during drying. (C) Koninklijke Brill NV, Leiden, 2012