Removal of small particles from solid surfaces is of critical importance for the microelectronic industry where ~50 % of yield losses are due to particle contamination. Laser cleaning is a technique developed in the late 1980s to remove micro and sub-micro scale particles from surfaces. In this study, a two-dimensional molecular dynamics approach is used to simulate the cleaning process. The model approximates laser energy heating the system that includes the particle, a substrate, and an energy transfer medium (ETM), which is a thin liquid film. The particles are removed through the explosive boiling of the ETM.
The Lennard-Jones 12-6 potential is used to model the interaction potential between a pair of molecules.
“r” is the distance between two molecules. “σ” is a measure of the molecule’s diameter (the distance where the potential is zero) and “ε” is the depth of the potential well, a measure of the strength of interaction.
The parameters σ and ε are chosen to fit the physical properties of the materials.
M.P. Allen, D.J. Tildesley: Computer Simulation of Liquids (Oxford University Press, New York 1989)
F. Ercolessi: A Molecular Dynamics Primer (Available: http://www.fisica.uniud.it/~ercolessi/md/md/)
S. Shukla: Optimization of Thickness of Energy Transfer Medium for Laser Particle Removal Process (2003) (Available: http://etd.lib.fsu.edu/theses/available/etd-11242003-113245/unrestricted/manuscript_final_24Nov.pdf)