Inspection system utilizing dark-field illumination
US4595289A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 25, 1984 |
| Grant date | Jun 17, 1986 |
| Priority date | — |
| Expiry date | Jan 25, 2004 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F7/70483
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
Integrated-circuit wafers and the lithographic masks and reticles used in their fabrication must be inspected for defects. Conventional systems accomplish such inspection by bright-field illumination and comparison of corresponding portions of two supposedly identical patterns on the workpiece. The minimum-size defect that can be so detected is set by misalignment between the patterns. Dark-field illumination of the portions to be compared significantly enhances the detection capabilities of such an inspection system. For a given misalignment, dark-field illumination permits the detection of defects at least four times smaller than those detectable in a conventional bright-field-illuminated system.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.