Patent ID: 7421973

Claim:
An ion shower, comprising: a plasma source operable to generate source gas ions within a chamber; an extraction assembly associated with a top portion of the chamber, and operable to extract ions from the top portion thereof; and a workpiece support structure associated with the top portion of the chamber, and operable to secure the workpiece having an implantation surface orientated facing downward toward the extraction assembly for implantation thereof, wherein the extraction assembly comprises a plurality of extraction electrodes vertically oriented with respect to one another and operable to extract the ions vertically from the top portion of the chamber, wherein a plasma electrode is a first extraction electrode of the plurality of extraction electrodes and is closest to the plasma within the chamber, and wherein the plurality of extraction electrodes comprise a plurality of respective extraction apertures extending therethrough, and wherein corresponding extraction apertures in the plurality of extraction electrodes are substantially aligned along a beam axis with respect to each other, respectively, and wherein at least one of the other extraction electrodes further comprise interstitial pumping apertures, wherein the interstitial pumping apertures are not aligned with respect to the extraction apertures with respect to the beam axis generated by beamlets passing through the extraction electrodes, and wherein the interstitial pumping apertures reduce a pressure near the extraction assembly external to the chamber.