Laser-assisted micron scale particle removal

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Abstract
A novel laser‐assisted particle removal (LAPR) technique capable of removing micron scale particles from semiconductor substrates is presented. In our preliminary experiments the contaminated substrates were dosed with water which preferentially adsorbs in the capillary spaces under and around the particles and were subsequently irradiated with transverse, electric, atomspheric CO2 laser pulses. At the CO2 laser wavelength the beam energy is mainly absorbed in the water and not the substrate. The subsequent explosive evaporation of the adsorbed water molecules produces forces many orders of magnitude larger than the adhesion forces between the particle and the substrate which propel the particles off the substrate surface. LAPR is inherently clean and can easily be incorporated into current or planned wafer processing systems.