Forming sub-45-nm high-aspect circle-symmetric spots with double bowtie aperture combined with metal-insulator-metal structure

In this paper, high-aspect circle-symmetric spots can be obtained through a novel lithography structure, named as the double bowtie aperture combined with the metal/insulator/metal (Ag/Pr/Ag) structure (DBMIM). The double bowtie aperture, composing of four triangle-hollow areas and a square-hollow area, can concentrate light into deep-subwavelength volumes with the enhanced field. And Ag layers, respectively located onto and beneath photoresist layer, can enhance light transmission and compensate transmission loss. This advantage aforementioned contributes to prolong light transmission distance. With COMSOL simulation, we discuss the influences of the novel lithography structure parameters on the quality of spots, and the simulation results demonstrate that sub-45-nm (λ/8) spots are obtained under optimal values.