Reflective optical element for EUV lithography

Patent metadata

Field	Value
Publication number	US-10649340-B2
Application number	US-201916257811-A
Country	US
Kind code	B2
Filing date	Jan 25, 2019
Priority date	Jul 27, 2016
Publication date	May 12, 2020
Grant date	May 12, 2020

Abstract

In order to prevent delamination of a reflective coating from the substrate under the influence of reactive hydrogen, a reflective optical element (50) for EUV lithography is provided, which has a substrate (51) and a reflective coating (54) for reflecting radiation in the wavelength range of 5 nm to 20 nm. A functional layer (60) is arranged between the reflective coating (54) and the substrate (51). With the functional layer, the concentration of hydrogen in atom % at the side of the substrate facing the reflective coating is reduced by at least a factor of 2.

First claim

What is claimed is:

1. A reflective optical element for extreme ultraviolet (EUV) lithography, comprising:
a substrate and a reflective coating configured to reflect radiation in a wavelength range of 5 nm to 20 nm;
a functional layer arranged between the reflective coating and the substrate, wherein the functional layer reduces a concentration of hydrogen in atom % at a side of the substrate facing the reflective coating by at least a factor of 2;
a microstructured layer arranged between the reflective coating and the substrate;
a polishing layer arranged on the functional layer or on the microstructured layer; and
an adhesion promoter layer arranged on the substrate.

2. The reflective optical element as claimed in claim 1 , wherein the functional layer comprises at least one of: tin, silver, molybdenum, ruthenium, iridium, nickel, iron, cobalt, copper, aluminum, platinum, zinc, manganese, lead, gold, palladium, tungsten, tantalum, and alloys, oxides, borides, and nitrides or carbides thereof.

3. The reflective optical element as claimed in claim 1 , wherein the microstructured layer comprises at least one of: nickel-phosphorus, nickel-boron, copper, silver, gold, platinum, iridium, tantalum, titanium, zirconium, tungsten, molybdenum and niobium.

4. The reflective optical element as claimed in claim 1 , wherein the functional layer is arranged between the reflective coating and the microstructured layer and/or between the microstructured layer and the substrate and/or within the microstructured layer and wherein the functional layer comprises at least one of tin, tin oxide, or tin nitride.

5. The reflective optical element as claimed in claim 1 , wherein the polishing layer is arranged on the functional layer.

6. The reflective optical element as claimed in claim 1 , wherein the polishing layer comprises at least one of: amorphous silicon, silicon dioxide, silicon nitride, gallium nitride and aluminum nitride.

7. The reflective optical element as claimed in claim 1 , wherein the functional layer is arranged between the polishing layer and the reflective coating.

8. The reflective optical element as claimed in claim 1 , wherein the substrate comprises at least one of: silicon, silicon carbide, silicon-infiltrated silicon carbide, quartz glass, titanium-doped quartz glass, glass, and glass ceramic.

9. The reflective optical element as claimed in claim 1 , wherein the adhesion promoter layer comprises at least one ply and further comprises at least one of:
ruthenium, chromium, platinum, iridium, copper, silver, gold, nickel, nickel-phosphorus, tantalum, titanium, zirconium, tungsten, molybdenum, and niobium.

10. The reflective optical element as claimed in claim 1 , wherein the reflective coating is configured as a multilayer system comprising alternately arranged layers of a material having a lower real part of a refractive index at an operating wavelength in the wavelength range of between 5 nm and 20 nm and of a material having a higher real part of the refractive index at the operating wavelength in the wavelength range of between 5 nm and 20 nm.

11. The reflective optical element as claimed in claim 1 , configured as a collector mirror.

12. An optical system for an EUV lithography apparatus having a reflective optical element as claimed in claim 1 .

13. An EUV lithography apparatus having the optical system as claimed in claim 12 .

14. The reflective optical element as claimed in claim 1 , wherein the functional layer is arranged between a first sublayer of the microstructured layer and a second sublayer of the microstructured layer.

15. The reflective optical element as claimed in claim 1 , wherein the functional layer has at least 100 micrometers thickness.

16. The reflective optical element as claimed in claim 1 , wherein the polishing layer is arranged above the microstructured layer and below the functional layer.

17. The reflective optical element as claimed in claim 1 , wherein:
the adhesion promoter layer is arranged on the substrate and below the microstructured layer; and
the polishing layer is arranged above the microstructured layer.

18. A reflective optical element for extreme ultraviolet (EUV) lithography, comprising:
a substrate and a reflective coating configured to reflect radiation in a wavelength range of 5 nm to 20 nm;
a functional layer that reduces a concentration of hydrogen in atom % at a side of the substrate facing the reflective coating by at least a factor of 2, wherein the functional layer comprises at least one of: tin, silver, molybdenum, ruthenium, iridium, iron, cobalt, aluminum, platinum, manganese, lead, gold, palladium, tungsten, tantalum, and alloys, oxides, borides, and nitrides or carbides thereof; and
a microstructured layer arranged between the reflective coating and the substrate,
wherein the functional layer is arranged between the reflective coating and the microstructured layer.

Assignees

• Zeiss Carl Smt Gmbh

Inventors

• Ehm Dirk Heinrich
• Shklover Vitaliy
• Ament Irene
• Schmidt Stefan-Wolfgang
• Becker Moritz
• Wiesner Stefan
• Urich Diana
• Meier Robert
• Winter Ralf
• Jalics Christof
• Kierey Holger
• Eva Eric

Classifications

• G02B5/0891

  Ultraviolet [UV] mirrors (apparatus for microlithography exposure G03F7/70; X-ray multilayer structures G21K1/06) · CPC title

• G03F7/70958

  Optical materials or coatings, e.g. with particular transmittance, reflectance or anti-reflection properties · CPC title

• G21K1/062

  Devices having a multilayer structure · CPC title

• G03F7/702 Primary

  Reflective illumination, i.e. reflective optical elements other than folding mirrors, e.g. extreme ultraviolet [EUV] illumination systems · CPC title

• G21K2201/067

  Construction details · CPC title