Inspecting apparatus for determining presence and location of foreign particles on reticles or pellicles
US4966457A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 19, 1989 |
| Grant date | Oct 30, 1990 |
| Priority date | — |
| Expiry date | Jan 19, 2009 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N2201/103
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A defect inspecting apparatus for determining the presence of a defect element adhering to either of the front and back surfaces of a thin film-like object to be inspected (the object having a light-transmitting property) applies two light beams of different wavelengths to a surface of the object and varies the incident angle of the light beams. A first photoelectric detector receives light of the two light beams reflected by or transmitted by the object, and a second photoelectric detector receives light of the two light beams scattered by the defect element. A discriminator determines the surface of the object to which the defect element adheres based on detection outputs of the photoelectric detectors.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.