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

Abstract

The invention discloses an ultra-high numerical aperture combined variable magnification extreme ultraviolet lithography objective lens and an optimization method, which can reduce the splicing numberof an exposure field of view and can improve the lithography quality and efficiency while increasing the size of an image space field of view perpendicular to a scanning direction by using a variablemagnification objective lens system design scheme. The image space numerical apertures of the objective lens system are 0.55 and 0.6, and the image space scanning view field widths are 1.5 mm and 1mm; the resolution of the photoetching objective lens can be improved due to the large numerical aperture, and the production efficiency of silicon wafers is improved due to the large image space scanning view field width; the incident angle of light on the reflector of the objective lens system is small, so that the design of a reflecting film layer is facilitated; the xy free-form surface profileof the codev is improved, the term number of free-form surface coefficients is increased, and the optimization freedom degree of the objective lens is increased; and a progressive optimization film layer design method for film layer design of a variable-magnification photoetching objective lens system is established, a film layer design scheme is provided for objective lens system design examplesof NA0.6 and NA0.55, and the average reflectivity of a film layer reaches 65% or above.

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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