Optical measurement and inspection method and apparatus having enhanced optical path difference detection
US6653649B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | Aug 20, 2001 |
| Grant date | Nov 25, 2003 |
| Priority date | — |
| Expiry date | Dec 11, 2021 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01B2290/25
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An optical measurement and inspection method and apparatus having enhanced path length detection uses a Fabry-Perot cavity to increase the phase detection sensitivity for light reflected from optical structures within a device under inspection. A partially reflective surface is inserted between an illumination subsystem and the device under inspection and the position of the partially reflective surface may be adjusted by a positioner to create the Fabry-Perot cavity between one or more surfaces within the device under inspection. The detection of phase changes is improved, providing improved sensitivity to optical path differences produced by structures within the device under inspection.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.