Subwavelength interference lithography based on a unidirectional surface plasmon coupler

A subwavelength interference lithography method is numerically demonstrated based on surface plasmon polaritons excited by unidirectional couplers, and the unidirectional coupler is composed of a conventional nanoslit with a nanochannel excavated from one side of this nanoslit. Simulation results show that a feature size of 50 nm half-pitch pattern can be obtained at the working wavelength of 365 nm, and this method can enhance the intensity of the interference pattern with higher contrast and field depth and is advantageous to the fabrication process in practical applications. (C) 2013 Society of Photo-Optical Instrumentation Engineers (SPIE)