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 7,463,413 B2
• Filed: 01/24/2006
• Issued: 12/09/2008
• 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
• Primary Examiner(s): AMARI, ALESSANDRO V
• Application Number:
  US11/337,807
• Publication Number:
  US 20060245058A1
• Time in Patent Office: 1,050 Days
• Field of Search: 359/359, 359584-590, 359/883, 359/884, 355/67, 355/71
• 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 on top of the multi-layer mirror a spectral purity enhancement layer, for example for application in an EUV lithographic apparatus. This spectral purity enhancement layer includes a first spectral purity enhancement layer, but between the multi-layer mirror and first spectral purity enhancement layer there may optionally be an intermediate layer or a second spectral purity enhancement layer and intermediate layer. Hence, multi-layer mirrors with the following configurations are possible: multi-layer mirror/first spectral purity enhancement layer; multi-layer mirror/intermediate layer/first spectral purity enhancement layer; and multi-layer mirror/second spectral purity enhancement layer/intermediate layer/first spectral purity enhancement layer. The spectral purity of normal incidence radiation may be enhanced, such that DUV radiation is diminished relatively stronger than EUV radiation.

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 and having a layer thickness d1 and 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, wherein the first material and the layer thickness d1 are selected to enlarge 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 with a wavelength in each wavelength range.

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 second 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 second layer thickness between 0.5 and 2.5 nm.

4. 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.

5. 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.

6. A multi-layer mirror according to claim 1, wherein the first material and the layer thickness d1 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.

7. A multi-layer mirror according to claim 1, wherein the first material and the layer thickness d1 of the layer comprised in the spectral filter top layer are designed such as to fulfill the following criteria:

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

9. 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.

10. 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.

11. A multi-layer mirror according to claim 1, wherein the first spectral purity enhancement layers comprises Si₃N₄ And has a layer thickness between 4 and 11 nm.

12. 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 a second material selected from Ru, BN, B₄C, B, C, TiN, Pd, Rh, Au, C₂F₄, SiN, Si₃N₄, SiC, MgF₂ or LiF.

13. 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 second layer thickness between 0.5 and 2.5 nm.

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 having a second layer thickness between 0.5 and 2.5 nm, and the first spectral filter top layer comprises SiN, Si₃N₄, having the layer thickness d1 between 4 and 11 nm.

15. A multi-layer mirror according to claim 1, wherein the layer thickness d1 is between 0.5 and 30 nm.

16. A lithographic apparatus comprising one or more multi-layer mirrors 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 and having a layer thickness d1 and 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, and the thickness d1 is between 0.5 and 30 nm, wherein the first material and the layer thickness d1 are selected to enlarge 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 with a wavelength in each wavelength range.

17. A lithographic apparatus according to claim 16, further comprising a plurality of multi-layer mirrors, wherein the materials of the layers and the layer thicknesses of the layers in the spectral filter top layers of the different multi-layer mirrors 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.

18. A method, comprising reflecting a beam of radiation with a multi-layer mirror, the 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 and having a layer thickness d1 and 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, and the thickness d1 is between 0.5 and 30 nm, wherein the first material and the layer thickness d1 are selected to enlarge 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 the beam of radiation, the beam having radiation with a wavelength in each wavelength range.

19. A method according to claim 18, further comprising reflecting the beam of radiation with a plurality of multi-layer mirrors.

20. A method according to claim 18, wherein the beam of radiation is reflected by a plurality of multi-layer mirrors, the materials of the layers and the layer thicknesses of the layers in the spectral filter top layers of the plurality of multi-layer mirrors are configured to minimize absorption and/or destructive interference of radiation having a wavelength selected from the 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.

21. 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; and

reflecting at least part of the beam of radiation on a multi-layer mirror, the 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 and having a layer thickness d1 and 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, and the layer thickness d1 is between 0.5 and 30 nm, wherein the first material and the layer thickness d1 are selected to enlarge 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 the beam of radiation, the beam having radiation with a wavelength in each wavelength range.