MEASUREMENT OF PARTICLE DEPOSITION VELOCITY TOWARD A HORIZONTAL SEMICONDUCTOR WAFER BY USING A WAFER SURFACE SCANNER

Abstract

The average particle deposition velocity toward a horizontal semiconductor wafer in a vertical airflow was measured by a wafer surface scanner (PMS SAS-3600) to shorten the exposure time and hence to improve repeatability. Polystyrene latex (PSL) spheres with diameters between 0.2 and 1.0 mum were used. For the present experiment, convection, diffusion, and sedimentation comprise important agents of the deposition mechanism. The mean and standard deviation of average deposition velocities were obtained from more than 10 data sets for each PSL sphere size, and the deposition velocity distributions from the measurement data were compared to the theoretical distributions.