Nanoparticle Removal Using Laser-Induced Plasma Shock Waves

Removal of sub-100 nm particles from substrates such as wafers and photo masks is an essential requirement in semiconductor, microelectronics, and nanotechnology applications. The proposed laser-induced plasma (LIP) based approach is an effective technique for removal of sub-100 nm particles, as the minimum tolerable particle on the substrates shrinks to sub-100 nm levels with each technological node. In the current study, our progress in sub-100 nm particle removal is reviewed, and the results of the kinetic theory simulations conducted to understand the dynamics of the gas molecule-nanoparticle interactions excited by the shock front are discussed. It is shown from the simulations and experiments that particles as small as sub-100 nm can be successfully detached. To explain possible mechanisms for the nanoparticle detachment in nanoscale, the concepts of rolling resistance moment and rocking motion are utilized as novel detachment mechanisms. The pressure experiments illustrate that the peak pressure levels achieved with the LIP shock wave fields are below damage thresholds of most substrate materials. The potential of the proposed approach as a practical noncontact, dry, fast, and damage-free method for removal of sub-100 nm particles is discussed.