Reflecting coating with optimized thickness

US10146136B2 · kind B2 · utility

Assignee

• Carl Zeiss SMT GmbH · DE

Inventors

• Martin Endres · Oberkochen, DE
• Hartmut Enkisch · Aalen, DE
• Stig Bieling · Aalen, DE

Key dates

• Filing date: Aug 28, 2015
• Grant date: Dec 4, 2018
• Expiry date: Sep 7, 2035

Classification

• Technology area (CPC G): Physics
• CPC primary: G21K1/062
• WIPO field: Optics
• WIPO sector: Instruments

Abstract

An illumination system for an optical arrangement such as an EUV lithography apparatus, having: at least one optical element which has at least one optical surface, on which a coating which reflects illumination radiation is applied, and an actuator device aligning the optical surface in at least two angular positions in the radiation path. The coating either has a thickness (dOPT1) at which a mean value (½(R1+R2)) formed from a thickness-dependent reflectivity (R1, R2) of the coating at the at least two angular positions is maximized or has a thickness (dOPT2) at which a maximum change (max(ΔR1/R1, ΔR2/R2)) in the reflectivity (R1, R2) caused by a thickness tolerance of the coating is minimized at the respective angular positions or else the reflecting coating has a thickness (dO2) at which the reflectivity (R1, R2) of the coating has the same magnitude in the at least two angular positions.