Removal of Fine Particles from Wafer Surface by Pulse Air Jets

Removal of fine particles from wafer surface by air jets was experimentally investigated in order to seek a surface-cleaning method that does not use cleaning liquids. Monodisperse polystyrene latex particles with diameters between 0.25-3.3 μm were deposited on a silicon wafer by gravitational settling and were removed by air jets from a rectangular nozzle. Particles were blown off the moment the air jet struck the wafer surface, and afterwards almost no particle reentrainment occurred. This suggests that sequential pulses of air jet are effective for the removal of fine particles. By exposure of wafer surface to sequential pulse jets, particles with a diameter of 0.25 1μm were almost completely blown off the surface. The experimental results also indicated that the removal efficiency of particles per pulse jet, which is the ratio of number of particles reentratined during exposure to a pulse jet and that before the exposure, is kept constant for each exposure to sequential pulse jets.