The water flow was supplied from a nozzle on a rotating disk and the droplet formation process on the disk was investigated experimentally for the fundamental study of the water-mark formation in CMP process. The rotating disk was made by an acrylic resin Formation processes of the droplets and water were observed by usmg a high speed video camera. As a result, it was found that the several patterns of water flow appeared on the rotating disk. And the patterns strongly depended on the rotation speed and contact angle of the liquid
