Method for aligning a mirror of a microlithographic projection exposure apparatus

US10101667B2 · kind B2 · utility

Assignee

• Carl Zeiss SMT GmbH · DE

Inventors

• Rolf Freimann · Aalen, DE
• Bernd Doerband · Aalen, DE
• Jochen Hetzler · Aalen, DE

Key dates

• Filing date: Oct 4, 2016
• Grant date: Oct 16, 2018
• Expiry date: Oct 4, 2036

Classification

• Technology area (CPC G): Physics
• CPC primary: G02B5/09
• WIPO field: Optics
• WIPO sector: Instruments

Abstract

A method for aligning a mirror of a microlithographic projection exposure apparatus, according to one formulation, involves: recording a first partial interferogram between a wave reflected at a first mirror segment (101) and a reference wave reflected at a reference surface (110, 310, 510), recording a second partial interferogram between a wave reflected at a second mirror segment (102) and a reference wave reflected at the reference surface, determining a phase offset between the first partial interferogram and the second partial interferogram, and aligning the first mirror segment and the second mirror segment in relation to one another in accordance with the determined phase offset, so that the distance of the relevant mirror segments (101, 102) from a respective predetermined, hypothetical surface in the direction of the respective surface normal is less than λ/10 at each point on the mirror segments, where λ denotes the operating wavelength of the mirror.