Method for measuring a reflectivity of an object for measurement light and metrology system for carrying out the method

US12422743B2 · kind B2 · utility

Assignee

• Carl Zeiss SMT GmbH · DE

Inventors

• Renzo Capelli · Heidenheim, DE
• Markus Koch · Neu-Ulm, DE
• Dirk Hellweg · Langenau, DE
• Walter Pauls · Wertingen, DE
• Grizelda Kersteen · Ulm, DE
• Klaus Gwosch · Oettingen, DE

Key dates

• Filing date: Apr 15, 2022
• Grant date: Sep 23, 2025
• Expiry date: Jun 7, 2044

Classification

• Technology area (CPC G): Physics
• CPC primary: G01N2021/95676
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

When measuring a reflectivity of an object for measurement light, initially the object and a reflectivity measurement apparatus are provided. The latter includes a measurement light source, an object holder for holding the object and a spatially resolving detector for capturing measurement light reflected by the object. A measurement light beam impinges on a section of the object within a field of view of the measurement apparatus. The reflected measurement light coming from the impinged-upon section of the object is captured. A surface area of the captured section is at most 50 μm×50 μm. The measurement is performed by the detector. Next, at least one reflectivity parameter of the object is determined on the basis of an intensity of the captured measurement light. The result is a measurement method and a metrology system operating therewith, whereby reflectivities in particular of very finely structured objects, such as lithography masks, can be measured with sufficient precision.