Method and system for detecting phase defects in lithographic masks and semiconductor wafers
US6727512B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Nov 5, 2002 |
| Grant date | Apr 27, 2004 |
| Priority date | — |
| Expiry date | Nov 5, 2022 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N2021/95676
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
Provided are apparatus and methods for detecting phase defects. The invention relies generally on the distortion of light as it passes through defects in phase shift masks to detect these defects. Light traveling through a defect, such as a bump in an etched area will travel at a different angle than light traveling through air. In order to enhance the signals generated from the defects, the invention in several embodiments provides a multiple element detector having at least four elements, arranged in a radially symmetric configuration. Individual elements of the detector are selected to form a differential signal based on the configuration of pattern lines in the area proximate to the defect. The resulting differential signal is used to generate an image signal and to identify phase defects.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.