Dark field inspection system with ring illumination
US9176072B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jul 16, 2010 |
| Grant date | Nov 3, 2015 |
| Priority date | — |
| Expiry date | Apr 29, 2031 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N2021/8822
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A dark field inspection system that minimizes the speckle noise due to sample surface roughness can include a plurality of beam shaping paths for generating a composite, focused illumination line on a wafer. Each beam shaping path can illuminate the wafer at an oblique angle. The plurality of beam shaping paths can form a ring illumination. This ring illumination can reduce the speckle effect, thereby improving SNR. An objective lens can capture scattered light from the wafer and an imaging sensor can receive an output of the objective lens. Because the wafer illumination occurs at oblique angles, the objective lens can have a high NA, thereby improving optical resolution of the imaging sensor, and the resulting signal level.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.