Removal of Fine Particles from Wafer Surface by Pulse Air Jets

Abstract

Removal of fine particles from wafer surface by air jets was experimentally investigated in order to seek an effective surface-cleaning method which uses no cleaning liquids. Monodisperse polystyrene latex particles with diameter between 0.25 and 3.3µm were deposited on a silicon wafer by gravitational settling and removed by air jets from a rectangular nozzle. Particles were blown off the moment the at jet struck the wafer surface, and afterwards no particle reentrainment occurred. This suggests that the sequential pulses of air jets are effective for the removal of fine particles. By exposure of wafer surface to sequential pulse air jets, particles with a diameter as small as 0.25µm were almost completely blown off the surface. The experimental results also indicated that the removal efficiency of particles per pulse air jet, which is the ratio of number of particles reentrained during an air jet exposure to that before the exposure, is kept constant for each exposure to sequential pulse air jets. © 1994, Hosokawa Powder Technology Foundation. All rights reserved.