Source multiplexing illumination for mask inspection
US9625810B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Mar 13, 2012 |
| Grant date | Apr 18, 2017 |
| Priority date | — |
| Expiry date | Feb 9, 2035 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F1/84
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
Methods and systems for source multiplexing illumination for mask inspection are disclosed. Such illumination systems enable EUV sources of small brightness to be used for EUV mask defect inspection at nodes below the 22 nm. Utilizing the multiple plane or conic mirrors that are either attached to a continuously rotating base with different angles or individually rotating to position for each pulse, the reflected beams may be directed through a common optical path. The light may then be focused by a condenser to an EUV mask. The reflected and scattered light from the mask may then be imaged by some imaging optics onto some sensors. The mask image may be subsequently processed for defect information.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.