Inspection apparatus and method for detecting flaws on a diffractive surface
US4943734A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 30, 1989 |
| Grant date | Jul 24, 1990 |
| Priority date | — |
| Expiry date | Jun 30, 2009 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N2201/1085
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An optical inspection system and method for detecting flaws on a diffractive surface such as a reticle or wafer, includes illuminating a surface to be inspected to generate a first scattered energy angular distribution in response to a flaw on the surface and a second scattered energy angular distribution in response to an unflawed surface; the first and second energy distributions are sensed and the minimum energy detection energy level is established; determining whether the minimum detected energy level is in a first or second predetermined energy range and indicating that no flaw is present when the minimum detected energy level is in the first range and a flaw is present when the minimum detected energy level is in the second range.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.