Multilayer extreme ultraviolet mirrors with enhanced reflectivity
US6738188B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | Jul 26, 2002 |
| Grant date | May 18, 2004 |
| Priority date | — |
| Expiry date | Jul 26, 2022 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T428/24355
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
The reflectivity of multilayered EUV mirrors tuned for 11-16 nm, for which the two-component Mo/Be and Mo/Si multilayered systems are commonly used, is enhanced by incorporating additional elements and their compounds mainly from period 5 of the periodic table. In addition, the reflectivity performance of the multilayer stacks is further enhanced by a numerical global optimization procedure by which the layer thicknesses are varied for optimum performance in, contradistinction to the constant layer thickness—i.e. constant partition ratio—multilayer stacks commonly designed and, fabricated hitherto. By incorporating additional materials with differing complex refractive indices in various regions of the stack, or by wholly replacing one of the components (typically Mo), we have observed peak reflectivity enhancements of up to 5% for a single reflector compared to a standard unoptimized stack.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.