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1. (WO2018158229) METHOD FOR CORRECTING A REFLECTIVE OPTICAL ELEMENT FOR THE WAVELENGTH RANGE BETWEEN 5 NM AND 20 NM.

Pub. No.:    WO/2018/158229    International Application No.:    PCT/EP2018/054769
Publication Date: Sat Sep 08 01:59:59 CEST 2018 International Filing Date: Wed Feb 28 00:59:59 CET 2018
IPC: G02B 1/12
G02B 5/08
G03F 7/20
Applicants: CARL ZEISS SMT GMBH
Inventors: KALDEN, Joachim
Title: METHOD FOR CORRECTING A REFLECTIVE OPTICAL ELEMENT FOR THE WAVELENGTH RANGE BETWEEN 5 NM AND 20 NM.
Abstract:
The invention relates to a method for correcting a reflective optical element for the wavelength range between 5 nm and 20 nm, comprising a multilayer system on a substrate, the multilayer system comprising layers consisting of at least two alternately arranged different materials with a different real component of the refractive index for a wavelength in the extreme ultraviolet wavelength range. Said method comprises the following steps: measuring the reflectivity distribution over the surface of the multilayer system; comparing the measured reflectivity distribution with a nominal distribution of the reflectivity over the surface of the multilayer system and determining at least one partial surface having a measured reflectivity above the nominal reflectivity; and irradiating the at least one partial surface with ions or electrons.