The Simulation Of Light Intensity Distribution Of SU-8 Thick Photoresist In Lithography Process

Ultraviolet lithography technology using SU-8 photoresist is an important microfabrication technology in the MEMS field.It overcomes the problem of insufficient aspect ratio of ordinary photoresist and is very suitable for manufacturing high-aspect-ratio MEMS microstructures.The use of process simulation technology to optimize the process can not only avoid the high cost and time-consuming problems caused by repeated experiments,but also use simulation technology to find the best process conditions,greatly improve the manufacturing performance.Therefore,lithography simulation technology is an indispensable part of lithography technology.Because the final shape of the photoresist after development depends largely on the exposure process,it is the most important step in the lithography process.By simulating the light intensity distribution in the photoresist,the morphology of the photoresist after development can be predicted.In order to make the simulation results more accurate and meet the needs of complex mask shapes,waveguide method based on vector diffraction theory can be used.This method is based on rigorous electromagnetic field theory and calculates the electromagnetic field distribution by solving Maxwell's equations.Therefore,the main work is to establish an accurate light intensity distribution calculation model for SU-8 thick photoresist based on the waveguide method.Combining initial parameters such as light source information,mask information and simulation model information to calculate the light intensity distribution in the photoresist after exposure and predict the final development of the photoresist.Finally,through mathematical abstraction,the mathematical model is converted into a specific programming language according to MATLAB and C++programming language to realize the simulation of the waveguide method.Combined with the specific SU-8 photolithography process,the simulation results of the light intensity distribution at normal incidence and oblique incidence are given.At the same time,the influence of some process parameters on the light intensity distribution is also analyzed and verified,such as air gap,substrate reflection,Oblique incident angle and so on.The simulation results are consistent with the theoretical analysis.In addition,the experimental results are compared with the corresponding simulation results,and the calculation shows that the error of feature size and oblique angle are both less than 5%.The simulation results are basically consistent with the experimental results,which verifies the correctness and accuracy of the model.Finally,suggestions are made for the optimization direction of the model and future work prospects.