Method for repairing reflective optical elements for EUV lithography

US11099484B2 · kind B2 · utility

Assignee

• Carl Zeiss SMT GmbH · DE

Inventors

• Robert Meier · Dallas, US
• Holger Kierey · Aalen, DE
• Christof Jalics · Aalen, DE
• Eric Eva · Aalen, DE
• Ralf Winter · Tegernsee, DE
• Arno Schmittner · Oberkochen, DE
• Alexey Sergeevich Kuznetsov · Zaltbommel, NL
• Vitaliy Shklover · Heidenheim, DE
• Christoph Nottbohm · Bielefeld, DE
• Wolfgang Merkel · Neu-Ulm, DE

Key dates

• Filing date: Jun 6, 2019
• Grant date: Aug 24, 2021
• Expiry date: Jun 6, 2039

Classification

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

Abstract

A cost-effective method for repairing reflective optical elements for EUV lithography. These optical elements (60) have a substrate (61) and a coating (62) that reflects at a working wavelength in the range between 5 nm and 20 nm and is damaged as a result of formation of hydrogen bubbles. The method includes: localizing a damaged area (63, 64, 65, 66) in the coating (62) and covering the damaged area (63, 64, 65, 66) with one or more materials having low hydrogen permeability by applying a cover element to the damaged area. The cover element is formed of a surface structure, a convex or concave surface, or a coating corresponding to the coating of the reflective optical element, or a combination thereof. The method is particularly suitable for collector mirrors (70) for EUV lithography. After the repair, the optical elements have cover elements (71, 72, 73).