Apparatus for scanning a flat surface to detect defects
US4812664A · kind A · utility
10Cited by
5References
10Claims
0Family size
Assignee
Inventor
Key dates
| Filing date | Nov 12, 1987 |
| Grant date | Mar 14, 1989 |
| Priority date | — |
| Expiry date | Nov 12, 2007 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N21/9501
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A surface scanner useful for detecting defects on the surface of a water that is being processed in a vacuum equipment employs a light beam that scans the wafer surface in an arc. The scanning light beam impinges on the wafer surface at a low angle of incidence which permits the beam to pass under photosensing elements disposed in an arcuate array substantially congruous with the arc defined by the scanning light beam. The photosensing elements are patterned close to the wafer surface to receive light scattered by defects on the wafer surface.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.