Subwavelength photolithography based on surface-plasmon polariton resonance

The use of surface-plasmon polariton (SPP) resonance in the optical near field of a metallic mask to produce fine patterns with a resolution of subwavelength scale is proposed. Preliminary numerical simulations indicate that the critical resolution is determined mainly by the thickness of the metallic mask. The surface of the metallic mask on the illuminated side collects light through SPP coupling, and the interference of SPPs on the exit side of the metallic mask results in enhanced optical intensity with high spatial resolution, which can facilitate nanolithography efficiently by use of conventional photoresist with simple visible or ultraviolet light sources. Several schemes for sub-half-wavelength lithography based on SPPs are described. Inasmuch as the technique is not diffraction limited, nanostructures can be reproduced photolithographically.