Fundamental study of air flow effects on liquid removal from wafer surface

Effects of air flow on droplet removal from wafer were investigated as the fundamental study of CMP cleaning. Deformation and movement of droplet on wafer by air flow were visualized by a high speed camera, and characteristics of droplet behavior were evaluated. Effects of wafer film types (Two types of wafer, Type-A and Type-B were used in this study) on droplet behavior were also investigated. Droplet on Type-A wafer was moved by the air flow with relatively large deformation. However in Type-B wafer, the droplet was moved with almost no deformation. Critical air velocity of droplet movement for Type-B wafer was lower than that of Type-A wafer. From these results, it was confirmed that the liquid removal processes by the air flow was strongly influenced by the property of the wafer surface.