Apparatus for detecting foreign particles on a surface of a reticle or pellicle
US4999510A · kind A · utility
39Cited by
10References
7Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Oct 27, 1989 |
| Grant date | Mar 12, 1991 |
| Priority date | — |
| Expiry date | Oct 27, 2009 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N2021/4721
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An apparatus for detecting foreign particles on a surface of a reticle or pellicle comprises an optical system through which a light beam forms a light spot on the surface. The surface and the light spot are shifted relatively so that the light spot scans the surface. Light detectors receive light scattered by a foreign particle and directed in different directions, respectively, and generated photoelectric outputs by which the presence of the foreign particle is discriminated. Beam diameter and scanning speed are varied to provide the most effective operation for particles of different sizes.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.