Dark field imaging defect inspection system for repetitive pattern integrated circuits
US5177559A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 17, 1991 |
| Grant date | Jan 5, 1993 |
| Priority date | — |
| Expiry date | May 17, 2011 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N2021/8822
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An optical inspection system for patterned semiconductor wafers generates a dark field image of the wafer by applying a collimated beam of monochrome light at an incident angle with respect to the surface of the wafer of between 8.degree. and a maximum angle defined by the numerical aperture of the imaging system and collecting the light which is scattered at angles approximately normal to the surface of the wafer and within the numerical aperture of the imaging system. In addition, the incident light is at an angle of 45.degree. in the surface plane of the wafer with respect to the rectangular lines which predominate in the pattern. Before forming the dark field image, the collected light is passed through a Fourier transform filter which substantially attenuates spatial frequency components corresponding to the pattern. In the resultant dark field image, defects in the pattern and contaminating particles are accentuated relative to the pattern features.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.