System and method for process variation monitor

US6862491B2 · kind B2 · utility

Assignee

• Applied Materials Israel Ltd. · IL

Inventors

• Evgeni Levin · Rehovot, IL
• Gilad Almogy · Givatayim, IL
• Efrat Rozenman · Gdera, IL

Key dates

• Filing date: May 22, 2002
• Grant date: Mar 1, 2005
• Expiry date: Mar 16, 2023

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y10S430/146
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

A method to extend the process monitoring capabilities of a semiconductor wafer optical inspection system so as to be able to detect low-resolution effects of process variations over the surface of a wafer at much higher sensitivity than heretofore possible. The method consists, in essence, of grouping sensed pixels by geometric blocks over the inspected surface and comparing each block with a corresponding one from another die on the same wafer, from another wafer or from a stored model image. In one embodiment of the invention, pixel values are compared directly and differences are thresholded at a considerably lower level than during a defects detection process. In another embodiment, there is calculated a signature for each block, based on the sensed light intensity values, and corresponding signatures are compared.