In an embodiment, a method includes: spinning a wafer around an axis of rotation at a center of the wafer; applying a first stream of liquid along a line starting from an initial point on the wafer adjacent to the center of the wafer, through the center of the wafer, and ending at an edge of the wafer; applying a second stream of liquid to an inner third of the line starting at the initial point and ending at a boundary point; applying a third stream of liquid to a middle third of the line starting at the boundary point; applying a fourth stream of liquid to an outer third of the line ending at the edge of the wafer; applying a fifth stream of liquid along the line starting from the initial point and ending at the edge of the wafer; and applying a stream of gas along the line starting from the initial point and ending at the edge of the wafer.