A system includes an integrated circuit (IC) design data base having a feature, a source configured to generate a radiation beam, a pattern generator (PG) including a mirror array plate and an electrode plate disposed over the mirror array plate, wherein the electrode plate includes a lens let having a first dimension and a second dimension perpendicular to the first dimension with the first dimension larger than the second dimension so that the lens let modifies the radiation beam to form the long shaped radiation beam, and a stage configured secured the substrate. The system further includes an electric field generator connecting the mirror array plate. The mirror array plate includes a mirror. The mirror absorbs or reflects the radiation beam. The radiation beam includes electron beam or ion beam. The second dimension is equal to a minimum dimension of the feature.