Design And Realization Of Exposure Light Source System For Maskless Lithography

With the improvement of the integration of electronic and optoelectronic devices,the processing accuracy of integrated circuit technology is also continuously improved.As a key technology in the manufacturing process of semiconductor devices and integrated circuits,lithography plays an important role in the modern society.With large-scale MEMS chip processing and excellent reflective digital light modulator,maskless lithography based on DMD has become the main digital lithography.The exposure light source provides illumination beams with uniform light intensity distribution for the entire lithography system,which is one of the core technologies of projection lithography.Illumination uniformity directly affects the uniformity of the exposure line width and the resolution of the single-field exposure area.However,in the field of digital lithography,there is still a lack of systematic research on exposure light source.In this thesis,focusing on the exposure light source of maskless lithography,the non-sequential mode of ZEMAX software is used to design the beam shaping and optimize the optical path structure.The main contents are as follows:(1)We analyze the ways of beam collimation and beam homogenization,and select the appropriate way to collimate and homogenize the exposure light source.In addition,we explore the influence of various parameters of the microlens array on the illumination area and illumination uniformity.Moreover,ZEMAX is used to design the collimation and homogenization of the LD light source.We use the cylindrical lens to reshape the fast and slow axes respectively to shape the elliptical spot into a circular spot.Finally,we use the above homogenization way to illuminate the circular spot.The circle spot is shaped into the rectangular spot with uniform light intensity distribution,and its illumination uniformity is 98.29% by simulation calculation.(2)ZEMAX is used to design the collimation and homogenization of the LED light source.We obtain a rectangular spot,whose illumination uniformity is 99.90%.In addition,a UV LED array is designed to increase the optical power to improve the lithography efficiency,and we obtain an illumination spot with a theoretical illumination uniformity of 97.79%.(3)The lithography system is built according to the simulation,and we test the illumination uniformity before and after homogenization,which prove that the uniformity of light intensity after homogenization is much higher than the illumination uniformity without homogenization.Also,we use the lithography system to expose single-pixel lines,and it is measured that the lines after uniform light are uniform in width and high in resolution.(4)In order to optimize the optical path structure of the exposure system,we design a red-violet integrated light source,which reduces the branches in the structure as well as the volume of the lithography system.In addition,we design a direct reflection projection module,which replaces the scheme of deflecting the light path by using a total internal reflection prism.This design can avoid the loss of light energy caused by the prism.Finally,a miniature projection system is added to simulate the overall exposure light path to verify the feasibility of the design.