An ion beam apparatus includes a plasma chamber with a grid assembly installed at one end of the plasma chamber and a plasma sheath controller disposed between the plasma chamber and the grid assembly. The grid assembly includes first ion extraction apertures. The plasma sheath controller includes second ion extraction apertures smaller than the first ion extraction apertures. When the plasma sheath controller is used in this configuration, the surface of the plasma takes on a more planar configuration adjacent the controller so that ions, extracted from the plasma in a perpendicular direction to the plasma surface, pass cleanly through the apertures of the grid assembly rather than collide with the sidewalls of the grid assembly apertures. A semiconductor manufacturing apparatus and method for forming an ion beam are also provided.