Device for controlling the cross-sectional properties of an ion implanter.

摘要

A defining aperture for an ion implanter (10) in which wafers (29) are implanted at high tilt angles, which aperture is configured to project a substantially circular beam pattern on the surface of the tilted wafer. One embodiment includes one or more movable aperture plates (78, 96) having elliptical apertures (86) formed therein operating in conjunction with a fixed aperture plate (76) having a circular aperture. Other embodiments include movable elliptical apertures, and a plate (81) having a circular aperture (83) wherein the plate is rotatable about an axis (85) perpendicular to the tilt axis (70) of the wafer. Where an electron flood ring is used, one or more movable rings (82) having elliptical apertures can be used.