Improvements in patterning quality and fidelity in plasmonic lithography incorporating optical proximity correction

Optical proximity correction (OPC) is a crucial technology in advanced lithography for improving image distortion. Subresolution-assisted features and edge manipulation on the photomask can facilitate improvements in patterning fidelity and provide a better process window. Prior OPC was adopted for projected optics with the limitation of a numerical aperture, which is not feasible in plasmonic lithography because of high-order diffraction in the near field. This study proposes an unconventional OPC that considers the surface plasmon behavior is proposed to correct the plasmonic mask. Metallic nanostructures were designed and fabricated as photomasks for plasmonic lithography. The placement of the metallic grooves was varied to investigate the patterning quality in plasmonic lithography, which acted as a subresolution assist feature. Moreover, an iterative algorithm was adopted to design the geometry of the plasmonic mask based on the desired optical image. An optical image with a better patterning fidelity was verified using the finite-difference time-domain method. Enhanced patterning capability was demonstrated in plasmonic lithography. The corresponding optical images were printed on a photoresist. The lithographic patterns assisted by the designed metallic structure demonstrated better patterning capabilities such as line-edge roughness, depth of the patterned photoresist, and corner fidelity. This method can be implemented for complex patterning in plasmonic lithography; moreover, it provides good control of the nanopattern shape.