EUV mirror and optical system comprising EUV mirror

US9915876B2 · kind B2 · utility

Assignee

• Carl Zeiss SMT GmbH · DE

Inventors

• Thomas Schicketanz · Aalen, DE
• Hans-Jochen Paul · Aalen, DE
• Christoph Zaczek · Heubach, DE

Key dates

• Filing date: Jul 10, 2015
• Grant date: Mar 13, 2018
• Expiry date: Apr 2, 2036

Classification

• Technology area (CPC G): Physics
• CPC primary: G21K2201/067
• WIPO field: Optics
• WIPO sector: Instruments

Abstract

An EUV mirror with a substrate and a multilayer arrangement including: a periodic first layer group having N1>1 first layer pairs of period thickness P1 and arranged on a radiation entrance side of the multilayer arrangement; a periodic second layer group having N2>1 second layer pairs of period thickness P2 and arranged between the first layer group and the substrate; and a third layer group having N3 third layer pairs arranged between the first and second layer groups. N1>N2. The third layer group has a third period thickness P3 which deviates from an average period thickness PM=(P1+P2)/2 by a period thickness difference ΔP. ΔP corresponds to the quotient of the optical layer thickness (λ/4) of a quarter-wave layer and the product of N3 and cos(AOIM), AOIM being the mean incidence angle for which the multilayer arrangement is designed.