Flow visualization of a particle deposition on silicon wafers in clean rooms

Flow field around silicon wafer in a clean room is discussed on the basis of experimental results obtained using smoke visualization and the Schlieren method. Several examples of flow pattern are presented to show the influence of aerodynamic conditions on particle transportation. The characteristic flow phenomena around stagnation point flow and vortices generated behind the wafer are made clear from the observed streamlines by the Schlieren method. The observed flow field for the vertical airflow over a horizontal wafer is compared with the simulation result given in Liu et al. (1987). The dependence of airflow on wafer surface temperature is also discussed. Results show that the fluid flow for a normal condition is an axisymmetric flow, while, for a wafer heated condition, the behavior of fluid flow is changed extremely and the effect of thermal convection is dominant compared with the main downward air flow.<
>