Theoretical Study Of Subwavelength Lithography Based On Sample Rotation

Subwavelength structure has important and extensive applications in micro-nano optics.Chemical synthesis or subwavelength lithography are usually used for their preparation.Surface plasmon interference lithography has some advantages in cost and resolution,so it is favored by researchers.However,the existing research mainly focuses on inscribing simple one-dimensional wavelength gratings.In order to inscribe complex two-dimensional subwavelength structure,surface plasmon interference is usually realized by multi-beam excitation,which obviously has some shortcomings,such as complex optical path,difficult technology and high cost.In this paper,surface plasmon interference subwavelength lithography based on sample rotation is studied theoretically.Two-dimensional square arrangement lattice structures,hexagonal arrangement lattice structures and circular gratings can be inscribed by multiple or continuous rotating and exposing lithography sample.On this basis,waveguide mode interference subwavelength lithography based on sample rotation is further studied,which can be used to inscribe various two-dimensional and three-dimensional sub-wavelength structures.Unlike surface plasmon interference lithography,waveguide mode interference lithography can achieve subwavelength structures of different sizes by changing the thickness of photoresist or the waveguide mode used for exposure.Specific research contents are as follows:?1?Based on the theory of surface plasmon interference lithography and coordinate matrix transformation,the surface plasmon interference subwavelength lithography based on sample rotation is studied theoretically.Two laser beams with 325 nm wavelength are used as excitation lights of surface plasmon.Two-dimensional square arrangement lattice structure with a period of 98 nm can be obtained by 90°rotation and two exposures of lithography sample.Hexagonal arrangement lattice structure can be obtained by 60°rotation and three exposures.The height of the triangle formed by three adjacent points in the lattice is 98 nm,which is the same as the period of the two-dimensional square arrangement lattice structures.Circular grating with a period of 98 nm can be obtained by continuous rotating and exposing lithography sample.?2?The zeroth-order waveguide mode interference lithography subwavelength lithography technology based on sample rotation is studied theoretically by using waveguide mode interference lithography theory and coordinate matrix transformation.The excitation lights of the waveguide mode are 325 nm lasers,and the TE₀ or TM₀ waveguide mode is excited at the corresponding excitation angle.Two-dimensional square arrangement lattice structures with a period of 103 nm can be obtained by 90°rotation and two exposures with TM₀ mode;Hexagonal arrangement lattice structure can be obtained by 60°rotation and three exposures.The height of the triangle formed by three adjacent points in the lattice is 103nm,which is the same as the period of the Two-dimensional square arrangement lattice structure;circular gratings with a period of 103 nm can be obtained by continuous rotating and exposing lithography samples.?3?The high-order waveguide mode interference subwavelength lithography based on sample rotation is studied theoretically.Laser with a wavelength of 442 nm is used as excitation light for high-order waveguide mode,and TE₅ waveguide mode interference is taken as an example,quasi-cuboid structure with a square arrangement with 100 nm in length and width and 85 nm in height can be obtained by 90°rotation and two exposures.quasi-octahedron structure with a hexagonal arrangement can be obtained by 60°rotation and three exposures.The shape and size,arrangement and period of these three-dimensional subwavelength structures can be changed by adjusting the rotation method of the sample,the thickness of photoresist and the waveguide mode used for exposure.