1. A method of processing a workpiece, comprising: applying a patterned mask to the workpiece; implanting ions into the patterned mask, where the ions are implanted based on an ion implant pattern, where the ion implant pattern defines a dose of ions to implant as a function of location on the workpiece and is calculated to reduce variability of a critical dimension of the workpiece; and processing the workpiece after the implanting, wherein the ions are selected from the group consisting of silicon and argon wherein the ion implant pattern is determined based on critical dimensions of the patterned mask measured at the plurality of locations and a compensation map, wherein the compensation map is determined empirically based on critical dimensions of a patterned mask of a second workpiece measured at a plurality of locations and measured critical dimensions of etched features of the second workpiece at the plurality of locations.