Removing 20 nm Particles Using a Supersonic Argon Particle Beam Generated with a Contoured Laval Nozzle

A cryogenic particle beam is an effective means of removing nano-sized contaminant particles, but the particle beam generated with a simple-hole nozzle has not been successful in removing particles smaller than 30 nm. Based on molecular dynamics (MD) simulation results that smaller cryogenic particles moving at a higher velocity are more effective in removing contaminant particles in the 10 nm range, a contoured Laval nozzle of a particular expansion angle and length was used in this study, instead of the simple-hole nozzle, to generate particle beams of high intensity and controlled size moving at high velocities. A variety of particle size and velocity were obtained by controlling the stagnation pressure/temperature and the back pressure, and using Laval nozzles with differing throat sizes and expansion angles. The new particle beams could remove almost completely a variety of ceramic and Cu particles, down to 20 nm size range, on a flat surface or in trenches.