Spectral purity filter for a multi-layer mirror, lithographic apparatus including such multi-layer mirror, method for enlarging the ratio of desired radiation and undesired radiation, and device manufacturing method

• US 20080316595A1
• Filed: 08/28/2008
• Published: 12/25/2008
• Est. Priority Date: 04/27/2005
• Status: Active Grant

• Current Assignee: ASML Netherlands BV (ASML Holding NV)
• Original Assignee: ASML Netherlands BV (ASML Holding NV)
• Inventors: Banine, Vadim Yevgenyevich, Bakker, Levinus Pieter, Van Herpen, Maarten Marinus Johannes Wilhelmus, Klunder, Derk Jan Wilfred
• Granted Patent: US 7,706,057 B2
• Time in Patent Office: Days
• US Class Current: 359/359
• CPC Class Codes: B82Y 10/00 Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
• CPC Class Codes: B82Y 40/00 Manufacture or treatment of nanostructures
• CPC Class Codes: G02B 1/10 Optical coatings produced by application to, or surface treatment of, optical elements G02B1/08 takes precedence
• CPC Class Codes: G02B 5/0816 Multilayer mirrors, i.e. having two or more reflecting layers G02B5/0883, G02B5/0891 take precedence
• CPC Class Codes: G02B 5/0891 Ultraviolet [UV] mirrors apparatus for microlithography exposure G03F7/70; X-ray multilayer structures G21K1/06
• CPC Class Codes: G02B 5/283 designed for the ultraviolet
• CPC Class Codes: G03F 1/24 Reflection masks; Preparation thereof
• CPC Class Codes: G03F 7/70575 Wavelength control, e.g. control of bandwidth, multiple wavelength, selection of wavelength or matching of optical components to wavelength
• CPC Class Codes: G03F 7/70958 Optical materials or coatings, e.g. with particular transmittance, reflectance or anti-reflection properties
• CPC Class Codes: G21K 1/062 Devices having a multilayer structure
• CPC Class Codes: G21K 2201/067 Construction details

Abstract

A multi-layer mirror includes a multi-layer stack. The multi-layer stack includes a plurality of alternating layers with a multi-layer stack top layer and a spectral filter top layer arranged on the multi-layer stack. The spectral filter top layer includes a first spectral purity enhancement layer that includes a first material m1 and has a first layer thickness d1, an intermediate layer that includes a second material m2 and has a second layer thickness d2. The intermediate layer is arranged on the multi-layer stack top layer. The first material is selected from SiN, Si₃N₄, SiO₂, ZnS, Te, diamond, CsI, Se, SiC, amorphous carbon, MgF₂, CaF₂, TiO₂, Ge, PbF₂, ZrO₂, BaTiO₃, LiF or NaF. The second material includes a material different from the first material, and d1+d2 has a thickness between 1.5 and 40 nm.

Claims

1. A multi-layer mirror, comprising:

a multi-layer stack, the multi-layer stack comprising a plurality of alternating layers with a multi-layer stack top layer and a spectral filter top layer arranged on the multi-layer stack, the spectral filter top layer comprising

a first spectral purity enhancement layer comprising a first material m1 and having a first layer thickness d1;

an intermediate layer comprising a second material m2 and having a second layer thickness d2, the intermediate layer being arranged on the multi-layer stack top layer, wherein the first material is selected from SiN, Si₃N₄, SiO₂, ZnS, Te, diamond, CsI, Se, SiC, amorphous carbon, MgF₂, CaF₂, TiO₂, Ge, PbF₂, ZrO₂, BaTiO₃, LiF or NaF, the second material comprises a material different from the first material, and d1+d2 has a thickness between 1.5 and 40 nm.

2. A multi-layer mirror according to claim 1, wherein the spectral filter top layer further comprises a cap layer on top of the first spectral purity enhancement layer, the cap layer comprising a third material selected from Ru, BN, B₄C, B, C, TiN, Pd, Rh, Au, C₂F₄, SiN, Si₃N₄, SiC, MgF₂ or LiF.

3. A multi-layer mirror according to claim 1, wherein the spectral filter top layer further comprises a cap layer on top of the first spectral purity enhancement layer, comprising Ru and having a layer thickness d4 between 0.5 and 2.5 nm.

4. A multi-layer mirror according to claim 1, wherein the intermediate layer comprises a metal.

5. A multi-layer mirror according to claim 1, wherein the second material is selected from Be, B, C, Si, P, S, K, Ca, Sc, Br, Rb, Sr, Y, Zr, Nb, Mo, Ba, La, Ce, Pr, Pa or U.

6. A multi-layer mirror according to claim 1, wherein the first spectral purity enhancement layer has an imaginary part of the complex index of refraction k≦

0.25*n+1.07, wherein n is the real part of the complex index of refraction.

7. A multi-layer mirror according to claim 1, wherein the first spectral purity enhancement layer has a real part of the complex index of refraction equal or larger than 2 and an imaginary part of the complex index of refraction equal or smaller than 1.6.

8. A multi-layer mirror according to claim 1, wherein the first and second materials and the first and second layer thicknesses are configured to minimize absorption and/or destructive interference of radiation having a wavelength selected from a first wavelength range of 5-20 nm, and maximize absorption and/or destructive interference of radiation having a wavelength selected from a second wavelength range of 100-400 nm.

9. A multi-layer mirror according to claim 1, wherein the multi-layer mirror is a normal incidence mirror.

10. A multi-layer mirror according to claim 1, wherein the multi-layer mirror is a normal incidence mirror configured to reflect radiation having a wavelength selected from a first wavelength range of 5-20 nm.

11. A multi-layer mirror according to claim 1, wherein the multi-layer mirror is a normal incidence Si/Mo multi-layer mirror configured to reflect radiation having a wavelength selected from the wavelength range of 12-15 nm.

12. A multi-layer mirror according to claim 1, wherein the first spectral purity enhancement layer comprises Si₃N₄, having a layer thickness between 4 and 11 nm, and wherein the intermediate layer comprises Mo having a layer thickness between 1 and 3 nm.

13. A multi-layer mirror according to claim 1, wherein the multi-layer stack top layer comprises a cap layer, the top layer comprising a material m5 selected from Ru, BN, B₄C, B, C, TiN, Pd, Rh, Au, C₂F₄, SiN, Si₃N₄, SiC, MgF₂ or LiF.

14. A multi-layer mirror according to claim 1, wherein the multi-layer stack top layer comprises a cap layer, the multi-layer stack top layer comprising Ru and having a layer thickness d5 between 0.5 and 2.5 nm.

15. A lithographic apparatus comprising a multi-layer mirror comprising a multi-layer stack, the multi-layer stack comprising a plurality of alternating layers with a multi-layer stack top layer and a spectral filter top layer arranged on the multi-layer stack, the spectral filter top layer comprising a first spectral purity enhancement layer comprising a first material m1 and having a first layer thickness d1;

an intermediate layer comprising a second material m2 and having a second layer thickness d2, the intermediate layer being arranged on the multi-layer stack top layer, wherein the first material is selected from SiN, Si₃N₄, SiO₂, ZnS, Te, diamond, CsI, Se, SiC, amorphous carbon, MgF₂, CaF₂, TiO₂, Ge, PbF₂, ZrO₂, BaTiO₃, LiF or NaF, the second material comprises a material different from the first material, and d1+d2 has a thickness between 1.5 and 40 nm.

16. A lithographic apparatus according to claim 15, further comprising a plurality of multi-layer mirrors, wherein the first and second material materials and the first and second layer thicknesses are configured to minimize absorption and/or destructive interference of radiation having a wavelength selected from a first wavelength range of 5-20 nm, and maximize absorption and/or destructive interference of radiation having a wavelength selected from a substantial part of the wavelength range of 100-400 nm.

17. A method for enlarging the ratio of radiation having a wavelength selected from a first wavelength range of 5-20 nm and radiation having a wavelength selected from a second wavelength range of 100-400 nm in a beam of radiation of a source emitting radiation in both wavelength ranges, the method comprising reflecting at least part of the beam of radiation on a multi-layer mirror comprising a multi-layer stack, the multi-layer stack comprising a plurality of alternating layers with a multi-layer stack top layer and a spectral filter top layer arranged on the multi-layer stack, the spectral filter top layer comprising a first spectral purity enhancement layer comprising a first material m1 and having a first layer thickness d1;

an intermediate layer comprising a second material m2 and having a second layer thickness d2, the intermediate layer being arranged on the multi-layer stack top layer, wherein the first material is selected from SIN, Si₃N₄, SiO₂, ZnS, Te, diamond, CsI, Se, SiC, amorphous carbon, MgF₂, CaF₂, TiO₂, Ge, PbF₂, ZrO₂, BaTiO₃, LiF or NaF, the second material comprises a material different from the first material, and d1+d2 has a thickness between 1.5 and 40 nm.

18. A method according to claim 17, wherein reflecting the at least part of the beam of radiation comprises reflecting the at least part of the beam on a plurality of multi-layer mirrors.

19. A method according to claim 17, wherein the first and second materials and the first and second layer thicknesses are configured to minimize absorption and/or destructive interference of radiation having a wavelength selected from the first wavelength range, and maximize absorption and/or destructive interference of radiation having a wavelength selected from the second wavelength range of 100-400 nm.

20. A device manufacturing method, comprising:

providing a beam of radiation;

patterning the beam of radiation;

projecting the patterned beam of radiation onto a target portion of a substrate;

enlarging the ratio of radiation having a wavelength selected from a first wavelength range of 5-20 nm and radiation having a wavelength selected from a second wavelength range of 100-400 nm by reflecting at least part of the beam of radiation on a multi-layer mirror comprising a multi-layer stack, the multi-layer stack comprising a plurality of alternating layers with a multi-layer stack top layer and a spectral filter top layer arranged on the multi-layer stack, the spectral filter top layer comprising a first spectral purity enhancement layer comprising a first material m1 and having a first layer thickness d1;

an intermediate layer comprising a second material m2 and having a second layer thickness d2, the intermediate layer being arranged on the multi-layer stack top layer, wherein the first material is selected from SiN, Si₃N₄, SiO₂, ZnS, Te, diamond, CsI, Se, SiC, amorphous carbon, MgF₂, CaF₂, TiO₂, Ge, PbF₂, ZrO₂, BaTiO₃, LiF or NaF, the second material comprises a material different from the first material, and d1+d2 has a thickness between 1.5 and 40 nm.