Illumination optical unit for EUV projection lithography

US10018917B2 · kind B2 · utility

Assignee

• Carl Zeiss SMT GmbH · DE

Inventors

• Stig Bieling · Aalen, DE
• Martin Endres · Oberkochen, DE
• Markus Deguenther · Aalen, DE
• Michael Patra · Oberkochen, DE
• Johannes Wangler · Oberkochen, DE

Key dates

• Filing date: Feb 17, 2017
• Grant date: Jul 10, 2018
• Expiry date: Feb 17, 2037

Classification

• Technology area (CPC G): Physics
• CPC primary: G03F7/70233
• WIPO field: Optics
• WIPO sector: Instruments

Abstract

An illumination optical unit for EUV projection lithography illuminates an object field, in which an object to be imaged is arrangeable. A first facet mirror of the illumination optical generates secondary light sources as images of an upstream light source. The first facet mirror includes mirrors which include a mirror surface smaller than 2 mm×2 mm. The first facet mirror is a distance |g| from the light source. The illumination optical unit includes a second facet mirror. The two facet mirrors are a distance b′ from each other. The individual mirrors of the first facet mirror have a focal length f in a plane of incidence of the illumination light on the individual mirrors such that [0.1 b′g/(g−b′)]<f<[10 b′g/(g−b′)].