Spectral purity filter and light monitor for an EUV reticle inspection system
US9348214B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Feb 3, 2014 |
| Grant date | May 24, 2016 |
| Priority date | — |
| Expiry date | Jun 26, 2034 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F7/70033
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An extreme ultraviolet (EUM) mask inspection system, comprising a light source to project EUV light along an optical axis, an illumination system to receive the EUV light from the source, the illumination system comprising a spectral purity filter (SPF), the SPF transmits a first portion of the EUV light along the optical axis toward a mask and the SPF comprising a plurality of at least partially reflective elements, said elements reflects a second portion of the EUV light off the optical axis, a projection system adapted to receive the first portion of the EUV light after it has illuminated the mask, a first detector array adapted to receive the image, and a second detector array to receive the second portion of the EUV light. The SPF may comprise one or more multilayer interference-type filters. Alternatively, the SPF comprises a thin film filter disposed on a grazing incidence mirror array.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.