The Simulation Of The Light Intensity Distribution In Optical Lithography Process

Nowadays, the products based on the MEMS technology are gradually applied in various fields of modern life. In the MEMS manufacturing process, due to the special nature of the device, usually selected the SU-8 photoresist as the mainstream process to form the high aspect ratio structure. In the past, in order to simulate the light intensity distribution in the SU-8 photoresist after exposure, and then predict the final morphology of the SU-8 photoresist after development, generally choose the traditional geometrical optics, namely the scalar diffraction theory. Under the premise of less precision, this method can give a relatively accurate result. With the rapid development of MEMS, its device dimensions become smaller and the structure become more complex. Modeling and simulation of the SU-8 phororesist by adopting the traditional geometrical optics, will lead to a significant deviation. At this time, it is urgent that a more accurately electromagnetic field model, namely the vector diffraction model should be established.The exposure model studied in this paper, selected the waveguide mathematical method based on the vector diffraction theory as the theoretical basis of the model. The air gap, the inclined angle of incident light and the substrate reflection have been considered in the model. Then, by means of mathematical abstraction and the concrete programming, establish the effective model which can describe the 2D/3D light intensity distribution for the vertical and inclined lithography. It can accurately describe the light intensity distribution in the resist. By combining with other existing module can formed a set of simulation software that can accurately simulate the whole lithography process. It can simulate the light intensity distribution and the resist development profile.Combined with the SU-8 photoresist in proximity lithography, the light intensity distribution and the final resist morphology corresponding to simulation results are given. At the same time, the influences of various process parameters on the optical lithography process are explored, including the air gap, substrate reflection, and inclined angle of incident light. The experiments for vertical and inclined lithography based on the SU-8 resist have been carried on. According to the comparison and analysis to the simulation results and the experiment results, the correctness of the light intensity distribution calculation model are verified.As for the light intensity in the lithography process simulation, the domestic research mainly focuses on the study of scalar diffraction theory, while the vector diffraction theory is little involved. Therefore, this work has some reference significance. Finally, the paper reviews the previous researches to make a conclusion and introduces some other new ideas which may improve the present simulations in further studies.