Method for removing a contamination layer by an atomic layer etching process

US11199363B2 · kind B2 · utility

Assignee

• Carl Zeiss SMT GmbH · DE

Inventors

• Fred Roozeboom · Eindhoven, NL
• Dirk Heinrich Ehm · Beckingen, DE
• Andrea Illiberi · Leuven, BE
• Moritz Becker · Stuttgart, DE
• Edwin Te Sligte · Eindhoven, NL
• Yves Lodewijk Maria Creijghton · Delft, NL

Key dates

• Filing date: Jan 6, 2020
• Grant date: Dec 14, 2021
• Expiry date: Jan 6, 2040

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y02T90/40
• WIPO field: Thermal processes and apparatus
• WIPO sector: Mechanical engineering

Abstract

A method for at least partially removing a contamination layer (24) from an optical surface (14a) of an optical element (14) that reflects EUV radiation includes: performing an atomic layer etching process for at least partially removing the contamination layer (24) from the optical surface (14a), which, in turn, includes: exposing the contamination layer (24) to a surface-modifying reactant (44) in a surface modification step, and exposing the contamination layer (24) to a material-detaching reactant (45) in a material detachment step. The optical element (14) is typically taken, before the atomic layer etching process is performed, from an optical arrangement, in particular from an EUV lithography system, in which the optical surface (14a) of the optical element (14) is exposed to EUV radiation (6), during which the contamination layer (24) is formed.