Sub-wavelength interference lithography by multi-beam TM₀/TE₀ modes excited by an MIM waveguide structure

We designed a lithography configuration based on a metal–insulator–metal waveguide structure to excite multi-beam interference based on TM 0 /TE 0 modes. The optical field intensity distribution of multi-beam TM 0 /TE 0 modes interference was numerically simulated using the finite element method. The results showed that the lithography configuration could excite three-beam interference based on TM 0 /TE 0 modes to fabricate a quasi-hexagonal close-packed circular lattice structure with a half-pitch resolution of 61 nm/73 nm. A square lattice structure with a half-pitch resolution of 46 nm/54 nm was fabricated by exciting the four-beam interference based on TM 0 /TE 0 modes. A quasi-hexagonal close-packed honeycomb-like lattice structure with a half-pitch resolution of 53 nm/64 nm was fabricated by exciting six-beam interference based on TM 0 /TE 0 modes. The resolution of the subwavelength structure could be controlled by changing the thickness of the photoresist and the excitation angle of the corresponding mode. This study enriches the fabrication of subwavelength structures with two-dimensional complex morphologies, expands the application of subwavelength structures, and provides a theoretical basis for further relevant research.