Perspectives on low-energy ion (and neutral) implantation

摘要

An important component of the control with ion implantation of atomic penetration depth and dose is the precision control of the ion beam incidence angle on the material surface. For implant doping of planar CMOS junctions, angled implants of 30 to 45 degrees are used to place "halo" doping into the channel region under the gate and normal incidence (0 degree) implants are used to form symmetric source/drain (SD) extension junctions on either side of a gate mask [1]. Normal incidence implants are also used to create channeled profiles for deep well structures in CMOS imagers [2]. For doping of SD regions in finFET transistors, precise control of ion beam incidence angles on the fin sidewall is needed to set the implanted beam dose and damage profiles as well as to avoid shadowing by adjacent fins and resist features [3]. Recently, angled ion implants with intentional shadowing by neighboring resist sidewalls have been suggested as a method to pattern fine line structures by increased etch rate of mask layers in regions exposed to the ion beam [4].