Projecting uniformity subwavelength pattern by plasmonic lithography with unidirectional surface plasmon coupler

A subwavelength interference nanolithography scheme is numerically demonstrated based on a metallic-insulator-metallic waveguide (MIMW) combined with two symmetrical surface plasmon unidirectional couplers. The unidirectional coupler is composed of a conventional nanoslit with a nanochannel excavated form onside of this nanoslit. Simulation results show that a feature size of 50 nm half-pitch and a depth of 100 nm uniformity pattern can be obtained at the working wavelength of 365 nm with the proposed scheme. This proposed scheme can enhance the intensity of the interference pattern with higher contrast and larger field depth which is advantageous to the fabrication process in practical applications.