Removal of Nanoparticles With Laser Induced Plasma

Abstract

A review of the recent progress in the understanding of the laser induced plasma (LIP) technique utilized for nanoparticle removal is presented. LIP nanoparticle removal technique has been successfully demonstrated for removal of 10–60 nm polystyrene latex (PSL) particles from silicon substrates. The motivation for LIP technique stems from the requirement for defect-free cleaning of wafers and lithography photomasks in the semiconductor and microelectronic fabrication industries as well as nanotechnology. The principle of LIP nanoparticle removal technique and progress in its applications as well as the LIP blast wave propagation are reviewed. In recent computational studies, the effects of the two consequences of LIP application, namely, radiation heating from the plasma core and the LIP shockwave thermo-mechanical (pressure and temperature) loading on the substrate and subsequent potential damage are investigated. Removal thresholds for polystyrene latex (PSL) nanoparticles from chromium (Cr) nanofilms using the LIP technique in air are reported. Rolling resistance moment as a particle removal mechanism is discussed and the main results and its implications in nanoparticle removal are summarized. For removal of smaller particles, pressure amplification techniques are employed to replace the in-air LIP. To achieve this purpose, shock tubes in air, wet-LIP and shock tubes submerged in water were investigated for obtaining maximized pressure levels. It is reported that the shockwave pressure can be substantially increased so that submerged shock tubes can generate pressure levels sufficient to remove particles as small as sub-10 nm.