Scatterometry alignment for imprint lithography

• US 20040021866A1
• Filed: 08/01/2002
• Published: 02/05/2004
• Est. Priority Date: 08/01/2002
• Status: Active Grant

• Current Assignee: Mii Newco, Inc.
• Original Assignee: Molecular Imprints, Inc. (Canon Inc.)
• Inventors: McMackin, Ian, Watts, Michael
• Granted Patent: US 7,027,156 B2
• Time in Patent Office: Days
• US Class Current: 356/401
• CPC Class Codes: B29C 2035/0827 using UV radiation
• CPC Class Codes: B29C 35/0888 using transparant moulds
• CPC Class Codes: B29C 59/022 characterised by the disposition or the configuration, e.g. dimensions, of the embossments or the shaping tools therefor
• CPC Class Codes: B29C 59/026 of layered or coated substantially flat surfaces
• 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

Abstract

Described are methods for patterning a substrate by imprint lithography. Imprint lithography is a process in which a liquid is dispensed onto a substrate. A template is brought into contact with the liquid and the liquid is cured. The cured liquid includes an imprint of any patterns formed in the template. Alignment of the template with a previously formed layer on a substrate, in one embodiment, is accomplished by using scatterometry.

Claims

1. A method of aligning a template with a portion of a substrate, comprising:

placing a patterned template at a spaced relation to a substrate, wherein the patterned template comprises a template alignment mark, and wherein the substrate comprises a substrate alignment mark, and wherein the template alignment mark and the substrate alignment mark are grating structures;

illuminating the template alignment mark and the substrate alignment mark with light at an angle that is substantially normal to a plane defined by the substrate;

measuring light at a first wavelength reflected from the template alignment mark and the substrate alignment mark at a non-zero order with a light detector;

determining a first alignment error of the template alignment mark with respect to the substrate alignment mark based on the light measurements collected at the first wavelength of light;

measuring light at a second wavelength reflected from the template alignment mark and the substrate alignment mark at a non-zero order;

determining a second alignment error of the template alignment mark with respect to the substrate alignment mark based on the light measurements collected at the second wavelength of light with the light detector;

determining an average alignment error, wherein the average alignment error is a function of the first and second alignment errors; and

altering the position of the template with respect to the substrate to compensate for the alignment error.

2. The method of claim 1, wherein the template alignment mark and the substrate alignment mark each comprise a grating having a spacing of between about 1 μ

m to about 3 μ

m.

3. The method of claim 1, wherein the template alignment mark and the substrate alignment mark each comprise a grating having a spacing of less than about 1 μ

m.

4. The method of claim 1, wherein the template alignment mark and the substrate alignment mark each comprise a grating having a spacing between about 100 and 1000 nm.

5. The method of claim 1, wherein the template alignment mark and the substrate alignment mark each comprise a first grating having a spacing of between about 1 μ

m to about 3 μ

m and a second grating having a spacing between about 100 and 1000 nm.

6. The method of claim 1, wherein the template alignment mark and the substrate alignment mark each comprise a first axis grating and a second axis grating, wherein the first axis grating is perpendicular to the second axis grating.

7. The method of claim 1, wherein measuring light at a first wavelength and measuring light at a second wavelength comprises using an array camera.

8. The method of claim 1, wherein measuring light at a first wavelength and measuring light at a second wavelength comprises using an array camera, wherein the array camera detector has a resolution capable of resolving different wavelengths of light reflected at the non-zero order.

9. The method of claim 1, wherein measuring light at a first wavelength and measuring light at a second wavelength comprises using an array camera, wherein the array camera detector has a resolution capable of resolving different wavelengths of light reflected at the non-zero order.

10. The method of claim 1, wherein measuring light at a first wavelength and measuring light at a second wavelength comprises using a spectrophotometer.

11. The method of claim 1, wherein measuring light at a first wavelength and measuring light at a second wavelength comprises measuring the +1 and −

1 order of the reflected light.

12. The method of claim 1, wherein measuring light at a first wavelength and measuring light at a second wavelength comprises using non achromatic lens coupled to an array camera.

13. The method of claim 1, wherein the first alignment error is calculated by comparing the positive n order light measurements at the first wavelength to the negative n order light measurements at the first wavelength, and wherein the second alignment error is calculated by comparing the positive n order light measurements at the second wavelength to the negative n order light measurements at the second wavelength.

14. A method of aligning a template with a portion of a substrate, comprising:

placing a patterned template at a spaced relation to a substrate, wherein the patterned template comprises a template alignment mark, and wherein the substrate comprises a substrate alignment mark, and wherein the template alignment mark and the substrate alignment mark are grating structures;

illuminating the template alignment mark and the substrate alignment mark with two incident light beams, wherein both of the incident light beams are directed at an angle that is substantially non-normal to a plane defined by the substrate;

measuring zero order light from both of the incident light beams at a first wavelength of light with a light detector;

determining a first alignment error of the template alignment mark with respect to the substrate alignment mark based on the light measurements collected from both beams of light at the first wavelength of light;

measuring zero order light from both of the incident light beams at a second wavelength of light with the light detector;

determining a second alignment error of the template alignment mark with respect to the substrate alignment mark based on the light measurements collected from both beams of light at the first wavelength of light;

determining an average alignment error, wherein the average alignment error is a function of the first and second alignment errors; and

altering the position of the template with respect to the substrate to compensate for the alignment error.

15. A method of aligning a template with a portion of a substrate, comprising:

placing a patterned template at a spaced relation to a substrate, wherein the patterned template comprises a template alignment mark, and wherein the substrate comprises a substrate alignment mark, and wherein the template alignment mark and the substrate alignment mark are grating structures;

illuminating the template alignment mark and the substrate alignment mark with two incident light beams, wherein both of the incident light beams are directed at an angle that is substantially non-normal to a plane defined by the substrate;

measuring non-zero order light from both of the incident light beams at a first wavelength of light with a light detector,

determining a first alignment error of the template alignment mark with respect to the substrate alignment mark based on the light measurements collected from both beams of light at the first wavelength of light;

measuring non-zero order light from both of the incident light beams at a second wavelength of light with the light detector;

determining a second alignment error of the template alignment mark with respect to the substrate alignment mark based on the light measurements collected from both beams of light at the first wavelength of light;

determining an average alignment error, wherein the average alignment error is a function of the first and second alignment errors; and

altering the position of the template with respect to the substrate to compensate for the alignment error.

16. A method of forming a pattern on a substrate comprising:

applying a predetermined volume of an activating light curable liquid to a first portion of the substrate in a predetermined pattern;

placing a patterned template at a spaced relation to a substrate, wherein the patterned template comprises a template alignment mark, and wherein the substrate comprises a substrate alignment mark, and wherein the template alignment mark and the substrate alignment mark are grating structures, and wherein a portion of the template contacts the activating light curable liquid disposed on the substrate;

illuminating the template alignment mark and the substrate alignment mark with light at an angle that is substantially normal to a plane defined by the substrate;

measuring light at a first wavelength reflected from the template alignment mark and the substrate alignment mark at a non-zero order with a light detector;

determining a first alignment error of the template alignment mark with respect to the substrate alignment mark based on the light measurements collected at the first wavelength of light;

measuring light at a second wavelength reflected from the template alignment mark and the substrate alignment mark at a non-zero order with the light detector;

determining a second alignment error of the template alignment mark with respect to the substrate alignment mark based on the light measurements collected at the second wavelength of light;

determining an average alignment error, wherein the average alignment error is a function of the first and second alignment errors;

altering the position of the template with respect to the substrate to compensate for the alignment error;

applying activating light to the activating light curable liquid, wherein the application of activating light substantially cures the activating light curable liquid, forming a first patterned area; and

separating the template from the cured liquid.

17. The method of claim 16, wherein the activating light curable liquid is substantially absent from the region between the substrate alignment mark and the template alignment mark.

18. The method of claim 16, wherein the patterned template comprises a first surface and a plurality of recesses formed in one or more patterning area of the template extending from the first surface toward a second surface of the template, where the recesses define a plurality of features in the first surface of the patterned template.

19. The method of claim 17, wherein the patterned template comprises a border formed about a perimeter of one or more of the patterning areas, wherein a depth of the border is greater than a depth of the recesses.

20. The method of claim 16, wherein the patterned template comprises two or more patterning areas, each of the patterning areas comprising a plurality of recesses, and wherein the two or more patterning areas are separated from each other by a channel, and wherein the depth of the channel is greater than a depth of the recesses in the patterning areas.

21. The method of claim 16, wherein separating the template from the cured liquid comprises moving the template and substrate into a substantially non-parallel orientation with respect to one another;

and moving the template and substrate apart from one another.

22. The method of claim 16, further comprising applying separating light before separating the template from the cured liquid, wherein separating light alters the chemical composition of a portion of cured liquid such that the adhesion of the template to the cured liquid is reduced.

23. The method of claim 16, further comprising applying separating light before separating the template from the cured liquid, wherein the separating light alters the chemical composition of a portion of the cured liquid such that a gas is released by the cured liquid near the interface of the template and the cured liquid.

24. The method of claim 16, further comprising providing an enclosure around at least the template and the substrate and inhibiting temperature variations greater than about 1.0°

C. within at least a portion of the enclosure.

25. The method of claim 16, further comprising applying a transfer layer to the substrate before applying the predetermined volume of the activating light curable liquid to the first portion of the substrate, wherein the transfer layer is etches at a different rate than an etch rate of the cured liquid under the same etching conditions.

26. The method of claim 16, wherein the activating light curable liquid has a viscosity of less than about 30 centipoise measured at 25°

C.

27. The method of claim 16, wherein at least a portion of the first surface of the patterned template comprises a surface treatment layer.

28. The method of claim 16, wherein applying the activating light curable liquid to a portion of the substrate comprises dispensing the liquid with a fluid dispenser.

29. The method of claim 16, wherein the activating light curable liquid comprises an ultraviolet light curable composition.

30. The method of claim 16, wherein positioning the patterned template and the substrate in a spaced relationship comprises positioning the patterned template at a distance of less than about 500 nm from the substrate.

31. A method of forming a pattern on a substrate comprising:

applying a predetermined volume of an activating light curable liquid to a first portion of the substrate in a predetermined pattern;

placing a patterned template at a spaced relation to a substrate, wherein the patterned template comprises a template alignment mark, and wherein the substrate comprises a substrate alignment mark, and wherein the template alignment mark and the substrate alignment mark are grating structures, and wherein a portion of the template contacts the activating light curable liquid disposed on the substrate;

illuminating the template alignment mark and the substrate alignment mark with two incident light beams, wherein both of the incident light beams are directed at an angle that is substantially non-normal to a plane defined by the substrate;

measuring zero order light from both of the incident light beams at a first wavelength of light with a light detector;

determining a first alignment error of the template alignment mark with respect to the substrate alignment mark based on the light measurements collected from both beams of light at the first wavelength of light;

measuring zero order light from both of the incident light beams at a second wavelength of light with the light detector;

determining a second alignment error of the template alignment mark with respect to the substrate alignment mark based on the light measurements collected from both beams of light at the first wavelength of light;

determining an average alignment error, wherein the average alignment error is a function of the first and second alignment errors;

altering the position of the template with respect to the substrate to compensate for the alignment error;

applying activating light to the activating light curable liquid, wherein the application of activating light substantially cures the activating light curable liquid, forming a first patterned area; and

separating the template from the cured liquid.

32. A method of forming a pattern on a substrate comprising:

applying a predetermined volume of an activating light curable liquid to a first portion of the substrate in a predetermined pattern;

placing a patterned template at a spaced relation to a substrate, wherein the patterned template comprises a template alignment mark, and wherein the substrate comprises a substrate alignment mark, and wherein the template alignment mark and the substrate alignment mark are grating structures, and wherein a portion of the template contacts the activating light curable liquid disposed on the substrate;

illuminating the template alignment mark and the substrate alignment mark with two incident light beams, wherein both of the incident light beams are directed at an angle that is substantially non-normal to a plane defined by the substrate;

measuring non-zero order light from both of the incident light beams at a first wavelength of light with a light detector;

determining a first alignment error of the template alignment mark with respect to the substrate alignment mark based on the light measurements collected from both beams of light at the first wavelength of light;

measuring non-zero order light from both of the incident light beams at a second wavelength of light with the light detector;

determining a second alignment error of the template alignment mark with respect to the substrate alignment mark based on the light measurements collected from both beams of light at the first wavelength of light;

determining an average alignment error, wherein the average alignment error is a function of the first and second alignment errors;

altering the position of the template with respect to the substrate to compensate for the alignment error;

applying activating light to the activating light curable liquid, wherein the application of activating light substantially cures the activating light curable liquid, forming a first patterned area; and

separating the template from the cured liquid.

33. An imprint lithography system, comprising:

a body;

a patterned template comprising a patterning area and a template alignment mark, wherein the patterning area comprises a plurality of recesses extending from a first surface of the template toward an opposing second surface of the template, and wherein a first alignment mark is defined by the recesses in the patterning area of the template, and wherein the template alignment mark is a grating structure;

a stage coupled to the body, wherein the stage is configured to support a substrate;

an imprint head coupled to the body, wherein the imprint head is configured to hold the patterned template proximate to the substrate during use;

a liquid dispenser coupled to the body, wherein the liquid dispenser is configured to dispense an activating light curable liquid onto at least a portion of the substrate during use;

an activating light source optically coupled to the body, wherein the activating light source is configured to direct activating light through the patterned template during use;

an analyzing light source optically coupled to a portion of the template

a detector optically coupled to the template, wherein the detector is configured to measure multiple individual wavelengths of light reflected from the substrate.

34. The system of claim 33, wherein the template alignment mark and the substrate alignment mark each comprise a grating having a spacing of between about 1 μ

m to about 3 μ

m.

35. The system of claim 33, wherein the template alignment mark and the substrate alignment mark each comprise a grating having a spacing of less than about 1 μ

m.

36. The system of claim 33, wherein the template alignment mark and the substrate alignment mark each comprise a grating having a spacing between about 100 and 1000 nm.

37. The system of claim 33, wherein the template alignment mark and the substrate alignment mark each comprise a first grating having a spacing of between about 1 μ

m to about 3 μ

m and a second grating having a spacing between about 100 and 1000 nm.

38. The system of claim 33, wherein the template alignment mark and the substrate alignment mark each comprise a first axis grating and a second axis grating, wherein the first axis grating is perpendicular to the second axis grating.

39. The system of claim 33, wherein the detector comprises an array camera.

40. The system of claim 33, wherein the detector comprises an array camera detector having a resolution capable of resolving different wavelengths of light reflected from the substrate at a non-zero order.

41. The system of claim 33, wherein the detector comprises a spectrophotometer.

42. The system of claim 33, wherein the detector comprises a non achromatic lens coupled to an array camera.

43. The system of claim 33, wherein the detector comprises a spectrophotometer, and wherein the spectrophotometer is optically coupled to light produced by the analyzing light source and reflected off of the substrate by a fiber optic cable.

44. The system of claim 33, wherein the analyzing light source is configured to apply a beam of light to the template substantially normal to a plane defined by the substrate.

45. The system of claim 33, wherein the analyzing light source is configured to apply a beam of light to the template at an angle that is substantially non-normal to a plane defined by the template.

46. The system of claim 33, further comprising a force detector coupled to the imprint head, wherein the force detector is configured to determine a resistive force applied to the template by the applied liquid when the template contacts the applied liquid.

47. The system of claim 33, further comprising a support structure coupled to the imprint head and to the stage, wherein the support structure comprises a material having a linear thermal expansion coefficient of less than about 20 ppm/°

C. at about 25°

C.

48. The system of claim 33, further comprising an enclosure around at least the imprint head and the stage, and a temperature control system, wherein the temperature control system is configure to inhibit temperature variations of greater than about 1°

C. within the enclosure during use.

49. The system of claim 33, wherein at least a portion of the first surface of the patterned template comprises a surface treatment layer.