A method and apparatus for directing an ion beam toward a surface of a substrate is disclosed. Certain embodiments of the invention relate generally to ion beam sources adapted to direct ion beams toward a surface of a substrate at an oblique angle of incidence relative to the surface. Certain embodiments of the invention are adapted to direct two ion beam portions toward a substrate surface, the ion beam portions having substantially equal throw distances. Preferred embodiments of the invention may be useful in etching applications, where the angle of incidence and throw distance of two ion beam portions are well suited for etching the surface of a substrate.