Catadioptric projection objective

US10042146B2 · kind B2 · utility

Assignee

• Carl Zeiss SMT GmbH · DE

Inventors

• Alexander Epple · Aalen, DE
• Vladimir Kamenov · Oberkochen, DE
• Toralf Gruner · Hennef (Sieg), DE
• Thomas Schicketanz · Aalen, DE

Key dates

• Filing date: Jul 20, 2017
• Grant date: Aug 7, 2018
• Expiry date: Jul 20, 2037

Classification

• Technology area (CPC G): Physics
• CPC primary: G03F7/70275
• WIPO field: Optics
• WIPO sector: Instruments

Abstract

A method of providing a catadioptric projection includes: providing a first partial objective for imaging an object field onto a first real intermediate image; providing a second partial objective for imaging the first real intermediate image onto a second real intermediate image, in which the second partial objective includes a concave mirror; providing a third partial objective for imaging the second intermediate image onto an image field, the third partial objective including an aperture stop; providing a first folding mirror and a second folding mirror; and providing an antireflection coating onto a surface of at least one lens that is directly adjacent to the concave mirror or that is separate from the concave mirror by a single lens, in which the antireflection coating is designed to have reflectivity of less than 0.2% for a wavelength between 150 nm and 250 nm and for an angle-of-incidence range between 0° and 30°.