Study on the Flow Structure between Rotating Disks for Semiconductor Photoresist Stripping Using High Concentrated Ozone Water

Abstract

In the photoresist stripping process of semiconductor manufacturing, the cleaning method with the ozone water and a disk-shaped nozzle is proposed in authors' previous studies. Moreover, it is suggested that the three-dimensional flow structure of the ozone water between a rotating silicon wafer and the disk-shaped nozzle affects photoresist stripping rate. The purpose of the present study is to reveal this flow structure. In order to reveal this flow structure, the visualization experiment with dye and stereoscopic micro-PTV measurement are conducted. As a result, the injected dye forms contrasting density, and a high concentrated area is indicated near the disk end. From this result, it is cleared that there is a transition radius of flow structure. The transition radius is different corresponding to experimental conditions. Nevertheless, it is suggested that the transition radius depends on a dimensionless number ReΩ / Res which is the ratio of rotational Reynolds number ReΩ and Reynolds number Res. From the result of stereoscopic micro-PTV measurement, it is cleared that the backward flow exists along r-axis. Furthermore, the backward flow keeps already reacted ozone water between two disks. As a result, it is suggested that the concentration of ozone water decreases near the circulation area.