Apparatus and method for gray field imaging
US11965835B2 · kind B2 · utility
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17Claims
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Key dates
| Filing date | Jun 22, 2022 |
| Grant date | Apr 23, 2024 |
| Priority date | — |
| Expiry date | Jul 28, 2042 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06T2207/30148
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A beam of light is directed from a light source at a wafer on a chuck. The beam of light is reflected off the wafer toward a 2D imaging camera. Movable focus lenses in the path of the beam of light can independently change the illumination conjugate and the collection conjugate. A structured mask in an illumination path can be used and the beam of light can be directed through apertures in the structured mask. A gray field image of a wafer in a zone without direct illumination is generated using the 2D imaging camera and locations of defects on the wafer can be determined using the gray field image.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.