Ultra-high numerical aperture combined variable magnification extreme ultraviolet lithography objective lens and optimization method

Abstract

The invention discloses an ultra-high numerical aperture combination variable magnification extreme ultraviolet lithography objective lens and an optimization method. The design scheme of the variable magnification objective lens system can reduce the exposure while increasing the size of the image square field of view perpendicular to the scanning direction. The splicing number of the field of view improves the quality and efficiency of lithography; the numerical aperture of the image side of the objective lens system is 0.55 and 0.6, and the width of the image side scanning field of view is 1.5mm and 1mm; a larger numerical aperture can improve the resolution of the lithography objective lens , the larger image square scanning field of view width improves the production efficiency of silicon wafers; the incident angle of light on the reflector of the objective lens system in the present invention is smaller, which is convenient for the design of the reflective film layer; the xy free-form surface of the codev is improved, Increased the number of terms of free-form surface coefficients, increasing the degree of freedom of objective lens optimization; established a progressive optimization film layer design method for the film design of variable magnification lithography objective lens systems, and designed examples for NA0.6 and NA0.55 objective lens systems The design scheme of the film layer is given, and the average reflectance of the film layer reaches more than 65%.

Description

technical field [0001] The invention belongs to the technical fields of optical design, semiconductor manufacturing equipment and chip manufacturing, and in particular relates to an ultra-high numerical aperture combined variable magnification extreme ultraviolet lithography objective lens and an optimization method. Background technique [0002] At present, with the development of the semiconductor manufacturing industry, the resolution of lithography projection is gradually developing towards a higher level, which requires that the lithography objective lens system should gradually increase the numerical aperture to meet the new challenges of the lithography industry. Combining variable magnification extreme ultraviolet lithography objective lenses can not only reasonably achieve a numerical aperture of 0.4-0.7, but also increase the size of the image square field of view perpendicular to the scanning direction, reduce the number of splices in the exposure field of view, an...

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Problems solved by technology

[0003] At present, there are no publicly reported papers and patents on NA55~0.6 combined variable magnification EUV lithography objective lens and gradient film system. The design of the highest numerical aperture variable magnification EUV lithography objective lens that has been published is Zeiss patent WO2016078818A1, which is the numerical aperture NA0 .55, Mx4 / My8 objective lens, but the structure of the objective lens system is unreasonable, multiple mirrors are grazing incidence, and the incident angle is large, it is difficult to obtain a matching uniform and high reflectivity coating, and the design method of the coating is not reported , structure and reflective properties of the objective lens

[0004] There is no complete disclosure of NA0.55~NA0.6 extreme ultraviolet lithography objective lens coating design methods and examples

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