Metrology system and method for measuring diagonal diffraction-based overlay targets

US11353321B2 · kind B2 · utility

Assignee

• KLA Corporation · US

Inventors

• Roie Volkovich · Migdal HaEmek, IL
• Ohad Bachar · Timrat, IL
• Nadav Gutman · Zichron Ya'akov, IL

Key dates

• Filing date: Jun 12, 2020
• Grant date: Jun 7, 2022
• Expiry date: Jun 12, 2040

Classification

• Technology area (CPC G): Physics
• CPC primary: G01M11/0207
• WIPO field: Optics
• WIPO sector: Instruments

Abstract

A metrology system is disclosed, in accordance with one or more embodiments of the present disclosure. The metrology system includes a stage configured to secure a sample, one or more diffraction-based overlay (DBO) metrology targets disposed on the sample. The metrology system includes a light source and one or more sensors. The metrology system includes a set of optics configured to direct illumination light from the light source to the one or more DBO metrology targets of the sample, the set of optics including a half-wave plate, the half-wave plate selectively insertable into an optical path such that the half-wave plate selectively passes both illumination light from an illumination channel and collection light from a collection channel, the half-wave plate being configured to selectively align an orientation of linearly polarized illumination light from the light source to an orientation of a grating of the one or more DBO metrology targets.