Removal of nano particles on silicon wafer by self-channeled plasma filament

The effective removal of nano particles from silicon wafer surface was demonstrated using the self-channeled plasma filament excited by a femtosecond (130 fs) Ti:Sapphire laser (lambda_p=790 nm). This process has achieved successfully the removal of 100 nm sized polystyrene latex (PSL) particles from the surface. The photoinduced self-channeled plasma filament in air reached a length of approximately 110-130 mm from the first focal spot with the diameters ranging from 40 to 50 mum at the input intensities more than 1.0 times 10¹⁴ W/cm². By the scan of wafer using the X-Y-Z stage during self-channeled plasma filament, the removal variation of nano particles on surface was observed in situ before and after plasma filament occurred. The cleaning efficiency was strongly dependent on the gap distance between the plasma filament and the surface. The removal efficiency of nano particles reached to 97% with no damage on the surface when the gap is 150 mum.