A method of exposing a wafer to a high-tilt angle ion beam and an apparatus for performing the same are disclosed. In an embodiment, a method includes forming a patterned mask layer over a wafer, the patterned mask layer including a patterned mask feature; exposing the wafer to an ion beam, a surface of the wafer being tilted at a tilt angle with respect to the ion beam; and moving the wafer along a scan line with respect to the ion beam, a scan angle being defined between the scan line and an axis perpendicular to an axis of the ion beam, a difference between the tilt angle and the scan angle being less than 50°.