Method and device for determining a reference point of an orientation marking on a substrate of a photolithographic mask in an automated manner

US9863760B2 · kind B2 · utility

Assignee

• Carl Zeiss SMT GmbH · DE

Inventors

• Michael Budach · Hanau, DE
• Ralf Schönberger · Wiesbaden, DE
• Michael R. Jost · Neuss, DE

Key dates

• Filing date: Jun 16, 2014
• Grant date: Jan 9, 2018
• Expiry date: Jan 14, 2035

Classification

• Technology area (CPC G): Physics
• CPC primary: G03F9/7088
• WIPO field: Optics
• WIPO sector: Instruments

Abstract

The invention relates to a method for automated determination of a reference point of an alignment mark on a substrate of a photolithographic mask, which method comprises the following steps: (a) performing a first line scan within a start region of the substrate in a first direction on a surface of the substrate, the alignment mark being arranged within the start region, for locating a first element of the alignment mark; (b) performing a second line scan within the start region in at least a second direction, which intersects the first direction, on the surface of the substrate for locating a second element of the alignment mark; (c) estimating the reference point of the alignment mark from the located first element and the located second element of the alignment mark; and (d) imaging a target region around the estimated reference point of the alignment mark in order to determine the reference point of the alignment mark, with the imaging being carried out at a higher resolution than the performance of the line scans in steps (a) and (b).