Patent ID: 7598495

Claim:
An ion implantation system comprising: an ion beam source that generates an ion beam; a beam line assembly that receives the ion beam from the ion beam source comprising: a mass analyzer that selectively passes selected ions; a focusing electrostatic particle trap that receives the ion beam and removes particles from the ion beam comprising: an entrance electrode comprising an entrance aperture and biased to a first base voltage; wherein the first surface of the entrance electrode is facing away from a center electrode and is approximately flat; wherein the second surface of the entrance electrode is facing toward the center electrode and is concave; wherein the center electrode is positioned a distance downstream from the entrance electrode comprising a center aperture and biased to a center voltage, wherein the center voltage is less than the first base voltage; wherein the first surface of the center electrode is facing toward the entrance electrode and is convex; wherein the second surface of the center electrode is facing away from the entrance electrode and is approximately flat; an exit electrode positioned a distance downstream from the center electrode comprising an exit aperture and biased to a second base voltage; and wherein the first surface of the exit electrode is facing toward the center electrode and is approximately flat; wherein the second surface of the exit electrode is facing away from the center electrode and is approximately flat; wherein a first electrostatic field is generated from the entrance electrode toward the center electrode and a second electrostatic field is generated from the exit electrode toward the center electrode; wherein the second base voltage is greater than the center voltage; and an end station that is downstream from the beam line assembly and receives the ion beam.