PIV measurement of vortical structures in a model of semiconductor single wafer cleaner

Abstract

In a single wafer spin cleaner, the wafer is rotated at high speed to spin off ultrapure water and clean air is blown perpendicular onto the surface to dry the wafer. Interaction between the rotating wafer and blown air generates vortices and the recirculation flow due to the vortices may cause reattachment of contaminants on the wafer surface. Therefore, we experimentally investigated vortical structures and the conditions of their formation in a modeled cleaner by using particle image velocimetry (PIV). The model was a 330 mm diameter rotating disk in a 520 mm diameter cylindrical stationary housing. Laminar blown air was from the housing inlet onto the rotating disk. The rotating speed of the disk was changed up to 2000 rpm and the blown air rate was up to 3.0 m3/min. Our PIV data show that vortices were generated on the upper and lower sides of the disk near the outer edge and collided with each other to form a large one. Additional large scale vortices were observed on the housing wall for the rotating speed of the disk above 200 rpm. The scale of the vortices increased and their generation frequency increased as the rotating speed increased. This work also investigated the optimum blown air flow rate against the rotating speed of the disk to prevent from generating the vortices.

Keywords

• single wafer cleaner
• semiconductor
• piv
• rotating disk
• vortex