System and method for performing optical inspection utilizing diffracted light
US6864971B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Mar 8, 2002 |
| Grant date | Mar 8, 2005 |
| Priority date | — |
| Expiry date | Jan 30, 2023 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N21/9501
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A system and method for performing optical inspection of structures on the surface of a semiconductor wafer. The wafer surface is illuminated with a polychromatic light source. A multiple-charged couple-device (CCD) camera is positioned to capture light diffracted by the structures on the wafer surface at the first order of diffraction. The captured light is then separated into a plurality of component wavelengths which are directed onto the CCDs. A digital filter creates a plurality of digitized diffractive images of the wafer surface at different component wavelengths. The diffractive images may be integrated and analyzed to detect defects in the structures, or may be, analyzed individually. An image at a particular wavelength may be selected and analyzed by using the known grating pitch of the structures to calculate the wavelength.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.