Calculation of a Projection Optical System for Extreme Ultraviolet Lithography

A method for designing optical systems by dividing them into separate groups (frontal, intermediate, and final) with subsequent independent calculation and subsequent coupling, as well as a program for visualizing the initial structure of a projection system for extreme ultraviolet lithography, are presented. The projection system is divided into three groups, and, in accordance with the characteristics of the optical system, the conditions for calculating the structure of each of these groups are determined. The parameters of the mirrors in each group are calculated separately. Then the groups are combined according to the rules for conjugating images and pupils to obtain the initial structure of a mirror optical system without shielding. To visualize the design process, the highlevel programming language MatLab and the optical design software Code V are used to combine the calculation process with the search and selection of a solution. The calculation and search process is intuitively controlled and fast, which makes it possible to obtain a large number of alternative options for initial structures in a short period of time.

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