Focus error detection apparatus and method having dual focus error detection path

US6750436B2 · kind B2 · utility

Assignee

• Applied Materials, Inc. · US

Inventors

• Haim Feldman · Yafia, IL
• Boris Golberg · Ashdod, IL
• Alexander Libinson · Holon, IL

Key dates

• Filing date: Jul 9, 2002
• Grant date: Jun 15, 2004
• Expiry date: Jul 9, 2022

Classification

• Technology area (CPC G): Physics
• CPC primary: G02B7/34
• WIPO field: Optics
• WIPO sector: Instruments

Abstract

An apparatus and method for focus error detection operable to receive light reflected from an inspected object and to determine a focus error on a surface of the inspected object, the focus error detection apparatus including optics and at least one detection apparatus, whereas the optics and the at least one detection apparatus define at least a first focus error detection path and a second focus error detection path, the first focus error detection path detects focus errors with a greater sensitivity than the second focus error detection path, while the second focus error detection path detects focus errors over a greater focus error range than the first focus error detection path.