Reflective optical element, and optical system of a microlithographic projection exposure apparatus

US9915873B2 · kind B2 · utility

Assignee

• Carl Zeiss SMT GmbH · DE

Inventors

• Hartmut Enkisch · Aalen, DE
• Hans-Jochen Paul · Aalen, DE
• Thomas Schicketanz · Aalen, DE
• Oliver Dier · Lauchheim, DE
• Joern WEBER · Aalen, DE
• Christian Grasse · Garching bei München, DE
• Ralf Winter · Tegernsee, DE
• Sebastian Strobel · Aalen, DE

Key dates

• Filing date: May 20, 2016
• Grant date: Mar 13, 2018
• Expiry date: May 20, 2036

Classification

• Technology area (CPC G): Physics
• CPC primary: G21K1/062
• WIPO field: Optics
• WIPO sector: Instruments

Abstract

A reflective optical element (50) having a substrate (52) and a multilayer system (51) that has a plurality of partial stacks (53), each with a first layer (54) of a first material and a second layer (55) of a second material. The first material and the second material differ from one another in refractive index at an operating wavelength of the optical element. Each of the partial stacks has a thickness (Di) and a layer thickness ratio (Γi), wherein the layer thickness ratio is the quotient of the thickness of the respective first layer and the partial stack thickness (Di). In a first section of the multilayer system, for at least one of the two variables of partial stack thickness (Di) and layer thickness ratio (Γi), the mean square deviation from the respective mean values therefor is at least 10% less than in a second section of the multilayer system.