High-resolution overlay alignment methods for imprint lithography

• US 6,921,615 B2
• Filed: 07/16/2001
• Issued: 07/26/2005
• Est. Priority Date: 07/16/2000
• Status: Active Grant

• Current Assignee: Board of Regents of the University of Texas System (University of Texas System)
• Original Assignee: Board of Regents of the University of Texas System (University of Texas System)
• Inventors: Sreenivasan, Sidlgata V., Choi, Byung J., Bailey, Todd, Colburn, Matthew
• Primary Examiner(s): Young, Christopher G.
• Application Number:
  US09/907,512
• Publication Number:
  US 20020098426A1
• Time in Patent Office: 1,471 Days
• Field of Search: 430/22, 430/30, 430/322
• US Class Current: 430/22
• CPC Class Codes: B29C 2035/0827 using UV radiation
• CPC Class Codes: B29C 2043/025 forming a microstructure, i.e. fine patterning
• CPC Class Codes: B29C 35/0888 using transparant moulds
• CPC Class Codes: B29C 37/005 Compensating volume or shape change during moulding, in general
• CPC Class Codes: B29C 37/0053 Moulding articles characterised by the shape of the surface, e.g. ribs, high polish mould construction therefor B29C33/42; surface shaping of articles B29C59/00; by incorporating filler in or near the surface B29C70/64
• CPC Class Codes: B29C 43/003 characterised by the choice of material
• CPC Class Codes: B29C 43/021 characterised by the shape of the surface
• 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: G03F 7/0002 Lithographic processes using patterning methods other than those involving the exposure to radiation, e.g. by stamping
• CPC Class Codes: G03F 9/00 Registration or positioning of originals, masks, frames, photographic sheets or textured or patterned surfaces, e.g. automatically G03F7/22 takes precedence; preparation of photographic masks G03F1/00; within photographic printing apparatus for making copies G03B27/00
• CPC Class Codes: Y10S 101/36 Means for registering or alignment of print plates on print press structure
• CPC Class Codes: Y10T 428/24802 Discontinuous or differential coating, impregnation or bond [e.g., artwork, printing, retouched photograph, etc.]

Abstract

A method of determining and correcting alignment during imprint lithography process is described. During an imprint lithographic process the template may be aligned with the substrate by the use of alignment marks disposed on both the template and substrate. The alignment may be determined and corrected for before the layer is processed.

Claims

1. A method of aligning a substrate with a patterned template spaced-apart from said substrate with a liquid material disposed therebetween, said substrate having substrate alignment marks disposed thereon and said patterned template having template alignment marks formed thereon, said method comprising:

adjusting a distance between said patterned template and said substrate such that said material contacts both said patterned template and said substrate, defining a contact region; and

varying an overlay placement of said patterned template with respect to said substrate such that said template alignment marks and said substrate alignment marks are substantially aligned, with said distance being established, based upon a viscosity associated with said material, to attenuate resistance to movement between said patterned template and said substrate due to properties of said material.

2. The method as recited in claim 1 wherein adjusting said distance further includes contacting both said pattern template and said substrate with said liquid while maintaining said template alignment marks and said substrate alignment marks outside of said contact region.

3. The method as recited in claim 2 further including, after varying said overlay placement, reducing said distance to expand said contact region to be in superimposition with both said template alignment marks and said substrate alignment marks.

4. The method as recited in claim 1 wherein adjusting said distance further includes contacting said material to be in superimposition with both said template alignment marks and said substrate alignment marks before varying said overlay placement.

5. The method as recited in claim 1 further including recording multiple patterns in separately dispensed regions of said material, with a subset of said multiple patterns being positioned in differing portions of said material and obtaining a desired alignment between said patterned template and each of said differing portions by repeating adjusting said distance and varying said overlay placement of said patterned template with respect to said substrate at each of said differing portions such that said template alignment marks and said substrate alignment marks are substantially aligned.

6. The method as recited in claim 1 further including recording multiple patterns in said material, with a subset of said multiple patterns being positioned in differing portions of said material and obtaining a desired alignment between said patterned template and each of said differing portions by repeating adjusting said distance and varying said overlay placement of said patterned template with respect to said substrate at a subset of said differing portions, defining initial alignment portions, with the remaining portions of said differing portions forming an additional subset, and determining alignment between said patterned template and said substrate at the portions associated with said additional subset as a function of a measurement of relative movement between said patterned template and said substrate measured from said initial alignment portions.

7. The method of claim 1 wherein varying said overlay placement further includes determining said alignment between said patterned template and said substrate by applying a first wavelength of light through said patterned template, wherein said first wavelength of light causes said substrate alignment marks to be in focus and said template alignment marks to be out of focus with respect to an analysis tool;

and applying a second wavelength of light through said patterned template, wherein said second wavelength of light causes said template alignment marks to be in focus and said substrate alignment marks to be out of focus with respect to said analysis tool.

8. Tho method as recited in claim 1 further including recording a pattern in said material by impinging a curing light upon said material to substantially cure said material, defining cured material, and separating said patterned template from said cured material.

9. The method of claim 1 wherein varying said overlay placement further includes determining said alignment between said patterned template and said substrate by providing a polarizing light alignment tool and a polarizing filter system, with said polarizing filter system being disposed between said polarizing light alignment tool and said patterned template, wherein said polarizing filter system comprises a first polarizing filter substantially oriented over said substrate alignment marks and a second polarizing filter substantially oriented over said template alignment marks, wherein said polarization of light capable of passing through said first polarization filter is substantially different than said polarization of light capable of passing through said second polarization filter.

10. The method of claim 1 further including providing said template alignment marks and said substrate alignment marks with symmetric geometric shapes, wherein varying said overlay placement further includes determining an alignment between said patterned template and said substrate by determining centers of said substrate and said template alignment marks, and comparing a location of the center of said template alignment marks to a location of the center of said substrate alignment marks.

11. The method as recited in claim 1 further including recording multiple patterns in separately dispensed regions of said material, with a subset of said multiple patterns being positioned in differing portions of said material and obtaining a desired alignment between said patterned template and each of said differing portions by repeating adjusting said distance and varying said overlay placement of said patterned template with respect to said substrate at each of said differing portions such that said template alignment marks and said substrate alignment marks are substantially aligned.

12. The method as recited in claim 1 wherein said properties include stiction.

13. A method of aligning a substrate with a patterned template spaced-apart from said substrate with a liquid material disposed therebetween, said substrate having substrate alignment marks disposed thereon and said patterned template having template alignment marks formed thereon, said method comprising:

adjusting a distance between said patterned template and said substrate such that said material contacts both said patterned template and said substrate, defining a contact region;

varying an overlay placement of said patterned template with respect to said substrate such that said template alignment marks and said substrate alignment marks are substantially aligned by adjustment of said overlay placement through altering dimensions of said patterned template, with said distance being established, based upon a viscosity associated with said material, to attenuate resistance to movement between said patterned template and said substrate due to properties of said material, with said properties including stiction; and

recording multiple patterns in separately dispensed regions of said material, with a subset of said multiple patterns being positioned in differing portions of said material and obtaining a desired alignment between said patterned template and each of said differing portions.

14. The method as recited in claim 13 wherein recording multiple patterns further includes obtaining a desired alignment between said patterned template and each of said differing portions by repeating adjusting said distance and varying said overlay placement of said patterned template with respect to said substrate at each of said differing portions such that said template alignment marks and said substrate alignment marks are substantially aligned.

15. The method as recited in claim 13 wherein recording multiple patterns further includes obtaining a desired alignment between said patterned template and each of said differing portions by repeating adjusting said distance and varying said overlay placement of said patterned template with respect to said substrate at a subset of said differing portions, defining initial alignment portions, with the remaining portions of said differing portions forming an additional subset, and determining alignment between said patterned template and said substrate at the portions associated with said additional subset as a function of a measurement of relative movement between said patterned template and said substrate measured from said initial alignment portions.

16. The method of claim 13 wherein altering dimensions further includes applying a compressive force to at least a portion of said patterned template.

17. The method of claim 13 wherein adjusting said overlay placement further includes altering dimensions of said patterned template by altering a temperature of said patterned template.

18. The method of claim 13 wherein adjusting said overlay placement further includes altering dimensions of said patterned template by applying an elongating force to at least a portion of said patterned template.

19. The method of claim 13 wherein varying said overlay placement further includes determining said alignment between said patterned template and said substrate by applying a first wavelength of light through said patterned template, wherein said first wavelength of light causes said substrate alignment marks to be in focus and said template alignment marks to be out of focus with respect to an analysis tool;

and applying a second wavelength of light through said patterned template, wherein said second wavelength of light causes said template alignment marks to be in focus and said substrate alignment marks to be out of focus with respect to said analysis tool.

20. The method of claim 13 wherein varying said overlay placement further includes determining said alignment between said patterned template and said substrate by providing a polarizing light alignment tool and a polarizing filter system, with said polarizing filter system being disposed between said polarizing light alignment tool and said patterned template, wherein said polarizing filter system comprises a first polarizing filter substantially oriented over said substrate alignment marks and a second polarizing filter substantially oriented over said template alignment marks, wherein said polarization of light capable of passing through said first polarization filter is substantially different than said polarization of light capable of passing through said second polarization filter.

21. A method of aligning a substrate with a patterned template spaced-apart from said substrate with a liquid material disposed therebetween, said substrate having substrate alignment marks disposed thereon and said patterned template having template alignment marks formed thereon, said method comprising:

adjusting a distance between said patterned template and said substrate such that said material contacts both said patterned template and said substrate, defining a contact region; and

varying an overlay placement of said patterned template with respect to said substrate such that said template alignment marks and said substrate alignment marks are substantially aligned by employing first and second fluxes of light, each of which has differing characteristics associated therewith, defining first and second characteristics, with said substrate alignment marks and said template alignment marks being responsive to said first characteristics, and defining a first response, and responsive to said second characteristics, defining a second response differing from said first response, with said distance being established, based upon a viscosity associated with said material, to attenuate resistance to movement between said patterned template and said substrate due to properties of said material, with said properties including stiction.

22. The method as recited in claim 21 further including recording multiple patterns in separately dispensed regions of said material, with a subset of said multiple patterns being positioned in differing portions of said material and obtaining a desired alignment between said patterned template and each of said differing portions by repeating adjusting said distance and varying said overlay placement of said patterned template with respect to said substrate at each of said differing portions such that said template alignment marks and said substrate alignment marks are substantially aligned.

23. The method of claim 21 further including providing an analysis tool in optical communication with said substrate alignment marks and said template alignment marks wherein said varying said overlay placement further includes associating said first flux of light with said first characteristic being a first wavelength, with said first response including said substrate alignment marks being in-focus and said template alignment marks to be out-of-focus with respect to said analysis tool;

and associating said second flux of light with said second characteristic being a second wavelength of light, with said second response including said template alignment marks being in-focus and said substrate alignment marks to being out-of-focus with respect to said analysis tool.

24. The method of claim 21 further including providing an analysis tool in optical communication with said substrate alignment marks and said template alignment marks wherein varying said overlay placement further associating with said first wavelength of light said first characteristics being a first polarization with said first response including said substrate alignment marks being sensed by said analysis tool and said analysis tool being precluded from sensing said template alignment marks;

and associating with said second flux of light said second characteristic being a second polarization, with said second response including said template alignment marks being sensed by said analysis tool and said analysis tool being precluded from sensing said substrate alignment marks.

25. The method of claim 21 wherein varying said overlay placement further includes determining said alignment marks between said patterned template and said substrate by applying said first and second flux of light to said patterned template, wherein said patterned template is composed of a first material and wherein said alignment marks are formed by depositing a second material, different from said first material, upon said patterned template, wherein said first and second materials are substantially transparent to a wavelength of a third flux of light used to cure said liquid material, and wherein said second material produces an analyzable mark with substantial contrast when said first and second flux of light is applied to said patterned template.

26. A method of aligning a substrate with a patterned template spaced-apart from said substrate with a liquid material disposed therebetween, said substrate having substrate alignment marks disposed thereon and said patterned template having template alignment marks formed thereon, said method comprising:

adjusting a distance between said patterned template and said substrate such that said material contacts both said patterned template and said substrate, defining a contact region; and

varying an overlay placement of said patterned template with respect to said substrate such that said template alignment marks and said substrate alignment marks are substantially aligned.