METHOD AND APPARATUS FOR CONSTANT ANGLE OF INCIDENCE SCANNING IN ION BEAM SYSTEMS

摘要

An ion beam (18) is scanned over a semiconductor wafer (30) in an ion implanter by deforming the wafer to have a concave contour selected to provide a constant angle of incidence of the scanned beam on the wafer surface. In one embodiment, the beam is scanned along one axis with a constant angle of incidence and is scanned about a center of deflection (46) along a second orthogonal axis. The wafer is deformed to have a concave cylindrical contour. The wafer can be clamped to a concave cylindrical platen surface by electrostatic or peripheral clamping. In a second embodiment, the beam is scanned in two dimensions about a center of deflection and the wafer is deformed to have a concave spherical contour. The wafer can be clamped to a concave spherical platen surface by electrostatic clamping.