Optical imaging system with laser droplet plasma illuminator
US8575576B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Feb 14, 2011 |
| Grant date | Nov 5, 2013 |
| Priority date | — |
| Expiry date | Oct 18, 2031 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01L22/12
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A wafer inspection system includes a laser droplet plasma (LDP) light source that generates light with sufficient radiance to enable bright field inspection at wavelengths down to 40 nanometers. Light generated by the LDP source is directed to the wafer and light from the illuminated wafer is collected by a high NA objective with all reflective elements. A detector detects the collected light for further image processing. The LDP source includes a droplet generator that dispenses droplets of a feed material. An excitation light generated by a laser is focused on a droplet of the feed material. The interaction of the excitation light with the droplet generates a plasma that emits illumination light with a radiance of at least 10 W/mm2-sr within a spectral range from 40 nanometers to 200 nanometers.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.