Design And Fabrication Of Micro-nano Structure Of Photocathode Substrate By Talbot Effect Lithography

With the continuous development of the defense industry,lowlight night vision technology has become more prominent in modern warfare.The micro-nano periodic functional structure can improve the optical performance of night vision devices and has great application value.The fabrication technology of micro-nano structures by the Talbot effect can simultaneously meet the requirements of large area,high precision,and low cost.It has become an important solution for the preparation of micronano periodic functional structures,and it occupies an important position in the field of micro-nano processing.In this paper,theoretical analysis and simulation of photocathode substrate micro-nano structure fabrication technology by Talbot effect lithography are carried out,and the mechanism of lithography based on the Talbot effect is explored.Model and simulate the photocathode substrate of night vision device.The influence of its structural parameters on the transmittance is analyzed and the optimal design is carried out.The cathode substrate of the night vision device is fabricated to verify the feasibility of the lithography based on the Talbot effect.The main research contents of the paper are as follows:(1)This paper introduces the principle of the Talbot effect and its development in lithography,and introduces the time domain finite difference method.Starting from the diffraction light field theory,after proving the consistency between the Rayleigh-Sommerfeld theory and the angle spectrum theory,the article analyzes the lithography principle of onedimensional and two-dimensional periodic structures based on the Talbot effect through the derivation of the angle spectrum theory.(2)Based on the time domain finite difference method,the paper conducts simulation analysis on one-dimensional masks and twodimensional masks.The article proves the pattern transfer ability of Talbot lithography and displacement Talbot lithography,and analyzes its influence on the structure period,and analyzes the influence of spiral displacement Talbot lithography on the duty cycle of two-dimensional periodic structures.When the range keeps increasing,the duty cycle is also increasing,and the duty cycle variation range is 17.2%-94.8%.(3)According to the structure of the photocathode substrate,the article analyzes the influence mechanism and law of its structural parameters on the transmittance,and optimizes the material thickness of each layer and the hole array of the cathode substrate.The average transmittance of light with a wavelength of 200～300nm is increased from about 0.01 to 0.05.The average transmittance of light with a wavelength of 300-800 nm is increased from about 0.5 to about 0.8,which improves the transmittance of the cathode substrate.In this paper,the fabrication process of the photocathode substrate of the night vision device is planned based on the semiconductor processing technology,and the periodic functional structure is processed by the spiral displacement Talbot lithography,and the cathode substrate structure is fabricated.A device performance test platform is built.And the optical performance of the cathode substrate structure is tested.The test results are compared with the simulation results,and the reasons for the difference are analyzed.The fabrication process of the photocathode substrate of the night vision device and the feasibility of the lithography based on the Talbot effect are verified.