Surface inspection apparatus
US6104481A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 2, 1998 |
| Grant date | Aug 15, 2000 |
| Priority date | — |
| Expiry date | Nov 2, 2018 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N21/9501
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A wafer surface inspection apparatus comprises a light source, an optical system for focusing the light beams from the light source onto the wafer surface, a scanning means for scanning the focused point over a predetermined range on the wafer surface, a photo detector including an photoelectric converter for sensing scattered light from the focused point, and a signal detector for detecting signals from the photo detector, in which the light source is a light source for emitting two different wavelengths, the optical system is adapted to focus the light beams of the two wavelengths on one and the same point on the wafer surface, and the photo detector is adapted to sense the two wavelengths separately, and further comprises a discriminating portion for discriminating between a foreign matter or a scratch on the wafer surface and a recess in a spot form existing on the wafer surface by utilizing outputs from the signal detector.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.