Optical inspection method and apparatus having an enhanced height sensitivity region and roughness filtering
US6714295B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | Oct 23, 2001 |
| Grant date | Mar 30, 2004 |
| Priority date | — |
| Expiry date | Oct 23, 2021 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N21/8806
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An optical inspection method and apparatus having an enhanced height sensitivity region and roughness filtering uses a Fabry-Perot cavity to increase the phase detection sensitivity for light reflected from surface defects having a height above a predetermined level. A partially reflective surface is inserted between an illumination subsystem and a surface under inspection. The position of the partially reflective surface with respect to the surface under inspection is adjusted to provide both filtering of defects below the predetermined level and enhance sensitivity for a region of defect heights above the predetermined level. The angular resolution of the inspection system is improved, providing far-field inspection that can detect small-profile defects having unacceptable heights. Media storage, semiconductor wafer and other precision surface manufacture may be improved by use of the techniques of the present invention.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.