Application of double exposure technique in plasmonic lithography

As the critical dimension (CD) of integrated circuits (ICs) becomes smaller and smaller, traditional optical lithography has a resolution limit due to the light diffraction effect, and surface plasmon lithography (SPL) beyond the diffraction limit developed in recent years is considered to be an alternative method to break through the diffraction limit. However, the fact that transverse magnetic (TM) waves are required to excite surface plasmon polaritons (SPP or SPPs) at the interface between a metal and a dielectric limits the application of surface plasmon lithography in imaging of the two-dimensional patterns in arbitrary shapes into photoresist. As an effective means of expanding existing lithography technology, double exposure (DE) is expected to be an effective means to solve this problem. Taking the advantage of imaging principle of DE, this paper proposes for the first time to apply DE to SPL to improve the imaging quality of SPL and theoretically analyzes the effect of DE on the improvement of SPL patterning in two dimensions. Simulation is performed in commercial software of Comsol Multiphysics 6.0. The simulation result verifies and proves that, in two-dimensional patterning, DE provides better imaging quality than single exposure.