Reflective optical element for EUV lithography
US8928972B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | Jul 22, 2011 |
| Grant date | Jan 6, 2015 |
| Priority date | — |
| Expiry date | Jul 22, 2031 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03F7/70958
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A stress-reduced reflective optical element for a working wavelength in the soft X-ray and extreme ultraviolet wavelength range includes a first multilayer system (4) of at least two alternating materials (41, 42) having different real parts of the refractive index at the working wavelength on a substrate (2), which exerts a layer stress on the substrate (2), and comprising a second multilayer system (6) of at least two alternating materials (61, 62) on a substrate (2), which exerts an opposed layer stress on the substrate (2) and is arranged between the first multilayer system (4) and the substrate (2), wherein one of the materials (61) of the second multilayer system (6) is nickel-vanadium-silicon, and wherein the ratio (G) of the overall thickness of nickel-vanadium-silicon layers (61) within one period (60) of the second multilayer system (6) to the overall thickness of the period (60) of the second multilayer system (6) is at least 0.25.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.