Broadband light interferometry for focal-map generation in photomask inspection
US11442021B2 · kind B2 · utility
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Key dates
| Filing date | Oct 5, 2020 |
| Grant date | Sep 13, 2022 |
| Priority date | — |
| Expiry date | Dec 30, 2040 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N2021/95676
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
Heights on a surface of a photomask are measured using broadband light interferometry. The heights include heights of patterned areas of the photomask. A focal map is produced from the measured heights on the surface of the photomask. To produce the focal map, the measured heights of the patterned areas are adjusted based on fill factors for the patterned areas. The photomask is inspected for defects, using the focal map.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.