Methods for processing a workpiece with fluorine radicals are provided. In one example implementation, the method includes a workpiece having at least one silicon layer and at least one silicon germanium layer. The method can include placing the workpiece on a workpiece support in a processing chamber. The method can include generating one or more species from a process gas in a plasma chamber. The method can include filtering the one or more species to create a filtered mixture. The method can include exposing the workpiece to the filtered mixture to remove at least a portion of the at least one silicon layer.