Method of fabricating reflection-mode EUV diffraction elements

• US 6,392,792 B1
• Filed: 12/05/2000
• Issued: 05/21/2002
• Est. Priority Date: 12/05/2000
• Status: Expired due to Term

• Current Assignee: EUV LLC (Intel Corporation)
• Original Assignee: Regents of the University of California (University of California)
• Inventors: Naulleau, Patrick P.
• Primary Examiner(s): Spyrou, Cassandra
• Assistant Examiner(s): Juba, Jr., John
• Application Number:
  US09/730,970
• Time in Patent Office: 532 Days
• Field of Search: 216/2, 216/24, 216/41, 216/26, 216/47, 359/565, 359/576, 359/350, 359/359, 359/360, 359/366, 359/369, 359/572, 359/900, 359/584, 359/585, 359/586, 378/34, 378/35
• US Class Current: 359/360
• 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 5/0825 the reflecting layers comprising dielectric materials only
• CPC Class Codes: G02B 5/1857 using exposure or etching means, e.g. holography, photolithography, exposure to electron or ion beams
• CPC Class Codes: G03F 1/24 Reflection masks; Preparation thereof
• CPC Class Codes: G03F 7/70058 Mask illumination systems
• CPC Class Codes: G03F 7/70216 Mask projection systems
• CPC Class Codes: G03F 7/70958 Optical materials or coatings, e.g. with particular transmittance, reflectance or anti-reflection properties
• CPC Class Codes: G21K 1/06 using diffraction, refraction or reflection, e.g. monochromators G21K1/10, G21K7/00 take precedence
• CPC Class Codes: G21K 1/062 Devices having a multilayer structure
• CPC Class Codes: G21K 2201/067 Construction details
• CPC Class Codes: Y10S 359/90 Methods

Abstract

Techniques for fabricating a well-controlled, quantized-level, engineered surface that serves as substrates for EUV reflection multilayer overcomes problems associated with the fabrication of reflective EUV diffraction elements. The technique when employed to fabricate an EUV diffraction element that includes the steps of: (a) forming an etch stack comprising alternating layers of first and second materials on a substrate surface where the two material can provide relative etch selectivity; (b) creating a relief profile in the etch stack wherein the relief profile has a defined contour; and (c) depositing a multilayer reflection film over the relief profile wherein the film has an outer contour that substantially matches that of the relief profile. For a typical EUV multilayer, if the features on the substrate are larger than 50 nm, the multilayer will be conformal to the substrate. Thus, the phase imparted to the reflected wavefront will closely match that geometrically set by the surface height profile.

Claims

1. A method of fabricating an EUV diffraction element comprising:

(a) forming an etch stack comprising alternating layers of first and second materials on a substrate surface where the two materials can provide relative etch selectivity;

(b) creating a relief profile in the etch stack wherein the relief profile has a defined contour and the relief profile has at least three levels wherein each level is formed by;

(i) forming a resist film on top of the stack;

(ii) exposing one or more patterned regions and developing to uncover one or more regions of the stack;

(iii) etching one layer of the stack where uncovered of resist; and

(iv) repeating steps (i) through (iii) at least once up to the number of stack layers available; and

(c) depositing a multilayer reflection film over the relief profile wherein the film has an outer contour that substantially matches that of the relief profile.

2. The method of claim 1 wherein the multilayer reflection film comprises alternating layers of a third material having a refractive index and a fourth material having a refractive index that is larger than that of the third material.

3. The method of claim 1 wherein the multilayer reflection film comprises about 10 to 200 layer pairs.

4. The method of claim 3 wherein the layer pairs have a periodicity of about 2 nm to 100 nm.

5. The method of claim 1 wherein the multilayer reflection film comprises alternating layers of molybdenum and silicon.

6. The method of claim 5 wherein the multilayer reflection film comprises about 10 to 200 layer pairs.

7. The method of claim 6 wherein the layer pairs have a periodicity of about 2 nm to 100 nm.

8. The method of claim 1 wherein the multilayer reflection film is formed of material selected from the group consisting of Mo—

Si, W—

C, Mo—

Be, Ru—

B₄C, Mo₂C—

Si, Ti—

C, V—

C.

9. The method of claim 8 wherein the multilayer reflection film comprises about 10 to 200 layer pairs.

10. The method of claim 9 wherein the layer pairs have a periodicity of about 2 nm to 100 nm.

11. The method of claim 1 wherein the etch stack is made up of Si and SiO₂.

12. The method of claim 1 wherein the heights of the individual etch stack layers ranges from 1 nm to 20 nm.

13. The method of claim 1 wherein the number of layers in the etch stack lies in the range of about 3 to 31.

14. An EUV device including a multilevel reflective diffraction element that comprises:

(a) a substrate having an etch stack comprising alternating layers of Si and SiO₂ on a substrate surface wherein the etch stack defines a relief profile having a desired contour; and

(b) a multilayer reflection film that covers the relief profile wherein the film has a contour that substantially matches that of the relief profile.

15. The device of claim 14 wherein the multilayer reflection film comprises alternating layers of a third material having a refractive index and a fourth material having a refractive index that is larger than that of the third material.

16. The device of claim 14 wherein the multilayer reflection film comprises alternating layers of molybdenum and silicon.

17. The device of claim 16 wherein the multilayer reflection film comprises about 10 to 200 layer pairs.

18. The device of claim 17 wherein the layer pairs have a periodicity of about 2 nm to 100 nm.

19. The device of claim 14 wherein the multilayer reflection film comprises about 10 to 200 layer pairs.

20. The device of claim 19 wherein the layer pairs have a periodicity of about 2 nm to 100 nm.

21. The device of claim 14 wherein the multilayer reflection film is formed of material selected from the group consisting of Mo—

Si, W—

C, Mo—

Be, Ru—

B₄C, Mo₂C—

Si, Ti—

C, V—

C.

22. The device of claim 21 wherein the multilayer reflection film comprises about 10 to 200 layer pairs.

23. The device of claim 22 wherein the layer pairs have a periodicity of about 2 nm to 100 nm.

24. The device of claim 14 wherein the heights of the individual etch stack layers ranges from 1 nm to 20 nm.

25. The device of claim 14 wherein the number of layers in the etch stack lies in the range of about 3 to 31.

26. A method of fabricating an EUV diffraction element comprising:

(a) forming an etch stack comprising alternating layers of Si and SiO₂ on a substrate surface;

(b) creating a relief profile in the etch stack wherein the relief profile has a defined contour; and

(c) depositing a multilayer reflection film over the relief profile wherein the film has an outer contour that substantially matches that of the relief profile.

27. The method of claim 26 wherein the heights of the individual etch stack layers ranges from 1 nm to 20 nm.

28. The method of claim 27 wherein the number of layers in the etch stack lies in the range of about 3 to 31.

29. A method of fabricating an EUV diffraction element comprising:

(a) forming an etch stack comprising alternating layers of first and second materials on a substrate surface where the two materials can provide relative etch selectivity wherein the heights of the individual etch stack layers ranges from 1 nm to 20 nm;

(b) creating a relief profile in the etch stack wherein the relief profile has a defined contour; and

(c) depositing a multilayer reflection film over the relief profile wherein the film has an outer contour that substantially matches that of the relief profile.

30. The method of claim 29 wherein the number of layers in the etch stack lies in the range of about 3 to 31.

31. A method of fabricating an EUV diffraction element comprising:

(a) forming an etch stack comprising alternating layers of first and second materials on a substrate surface where the two materials can provide relative etch selectivity wherein the number of layers in the etch stack lies in the ranges of about 3 to 31;

(b) creating a relief profile in the etch stack wherein the relief profile has a defined contour; and

(c) depositing a multilayer reflection film over the relief profile wherein the film has an outer contour that substantially matches that of the relief profile.

32. An EUV device including a multilevel reflective diffraction element that comprises:

(a) a substrate having an etch stack comprising alternating layers of first and second materials on a substrate surface wherein the etch stack defines a relief profile having a desired contour and wherein the heights of the individual etch stack layers ranges from 1 nm to 20 nm; and

(b) a multilayer reflection film that covers the relief profile wherein the film has a contour that substantially matches that of the relief profile.

33. The device of claim 32 wherein the number of layers in the etch stack lies in the range of about 3 to 31.

34. An EUV device including a multilevel reflective diffraction element that comprises:

(a) a substrate having an etch stack comprising alternating layers of first and second materials on a substrate surface wherein the etch stack defines a relief profile having a desired contour and wherein the number of layers in the etch stack lies in the range of about 3 to 31; and

(b) a multilayer reflection film that covers the relief profile wherein the film has a contour that substantially matches that of the relief profile.