We show that a significant fraction of the overlap in advanced logic technologies originates in the as-implanted dopant profile. As a consequence, small changes in the as-implanted profile have a large impact on device characteristics. We have developed a virtual, high-performance, planar, bulk, 65 nm technology that we use as a platform to investigate the impact of imperfections in the extension implant stemming from (1) contamination of the beam with higher energy ions and (2) angular alignment of the incident ion beam to the wafer. We find that a deceleration ratio of 7 and an energy contamination equal to 1% of the total dose double the off current. Small (of the order 1 degrees) beam steering of the incident beam as seen by the wafer leads to large changes in on current (of the order of 20%) and speed. Steering that results in shadowing of the source has a far larger impact than drain-side shadowing. This can be alleviated significantly by a quad implant, provided the tilt angle is sufficiently large, on the order > 5 degrees. A quad implant twisted by 45 degrees allows essentially complete recovery of the nominal device characteristics, even where beam steering leads to source-side shadowing. (c) 2006 American Vacuum Society.