Beam pen lithography

• US 9,021,611 B2
• Filed: 02/18/2010
• Issued: 04/28/2015
• Est. Priority Date: 02/18/2009
• Status: Active Grant

• Current Assignee: Northwestern University
• Original Assignee: Northwestern University
• Inventors: Mirkin, Chad A., Zheng, Gengfeng, Huo, Fengwei
• Primary Examiner(s): Johnston, Phillip A
• Assistant Examiner(s): LUCK, SEAN M
• Application Number:
  US13/202,142
• Publication Number:
  US 20110305996A1
• Time in Patent Office: 1,895 Days
• Field of Search: 850/55, 850/57, 850/58
• US Class Current: 850/55
• CPC Class Codes: G03F 7/2051 Exposure without an original mask, e.g. using a programmed deflection of a point source, by scanning, by drawing with a light beam, using an addressed light or corpuscular source G03F7/70 takes precedence
• CPC Class Codes: G03F 7/70291 Addressable masks, e.g. spatial light modulators [SLMs], digital micro-mirror devices [DMDs] or liquid crystal display [LCD] patterning devices
• CPC Class Codes: G03F 7/70383 Direct write, i.e. pattern is written directly without the use of a mask by one or multiple beams maskless lithography using a programmable mask G03F7/70291
• CPC Class Codes: G03F 7/70466 Multiple exposures, e.g. combination of fine and coarse exposures, double patterning or multiple exposures for printing a single feature stitching G03F7/70475
• CPC Class Codes: G03F 7/70525 Controlling normal operating mode, e.g. matching different apparatus, remote control or prediction of failure
• CPC Class Codes: G03F 7/70958 Optical materials or coatings, e.g. with particular transmittance, reflectance or anti-reflection properties

Abstract

The disclosure relates to methods of beam pen lithography using a tip array having a plurality of transparent, elastomeric, reversibly-deformable tips coated with a blocking layer and apertures defined in the blocking layer to expose tip ends of the tips in the array. The tip array can be used to perform a photolithography process in which the tips are illuminated with a radiation that is channeled through the tips and out the apertures to expose a photosensitive substrate. Also disclosed are tip arrays formed of polymers and gels, apparatus including the tip arrays and radiation sources, and related apparatus for selectively masking tips in the tip array from radiation emitted from the radiation source.

Claims

1. A tip array comprising:

a tip substrate layer comprising a first surface and an oppositely disposed second surface;

a plurality of tips fixed to the first surface, the tips each comprising a tip end disposed opposite the first surface, the tip substrate layer and the plurality of tips being formed from an at least translucent and deformable material, the tip substrate layer and the plurality of tips being formed from the same material, the tips having a radius of curvature of less than 1 μ

m, wherein the tips are arranged in a pre-determined pattern extending in at least two dimensions;

a blocking layer coated on the plurality of tips and the first surface; and

a plurality of apertures defined in the blocking layer exposing the tip ends of the plurality of tips,

wherein the tip array is configured to generate a near field optical effect when brought in proximity with a substrate, and deformation of the tips when in contact with the substrate provides a change in the size of the near-field optical effect.

2. The tip array of claim 1, wherein the tips are arranged in a regular periodic pattern.

3. The tip array of claim 1, wherein the tips are identically-shaped.

4. The tip array of claim 1, wherein the tips are pyramidal.

5. The tip array of claim 1, wherein the thickness of the tip substrate layer is 50 μ

m to 100 μ

m.

6. The tip array of claim 1, further comprising an at least translucent rigid support adhered to the second surface of the substrate layer.

7. The tip array of claim 1, wherein the tip substrate layer and tips have a combined thickness of less than 200 μ

m.

8. The tip array of claim 1, wherein the blocking layer is a metal.

9. The tip array of claim 1, wherein the at least translucent material comprises a polymer.

10. The tip array of claim 1, wherein the at least translucent material comprises a crosslinked polymer or a polymer gel.

11. The tip array of claim 1, wherein the at least translucent material is elastomeric.

12. The tip array of claim 1, wherein the at least translucent material is reversibly deformable.

13. The tip array of claim 1, wherein the at least translucent material is substantially transparent.

14. The tip array of claim 1, wherein the at least translucent material comprises polydimethylsiloxane (PDMS).

15. The tip array of claim 1, wherein the PDMS comprises a trimethylsiloxy terminated vinylmethylsiloxane-dimethysiloxane copolymer, a methylhydrosiloxane-dimethylsiloxane copolymer, or a mixture thereof.

16. The tip array of claim 1, wherein the aperture has a diameter in a range of 30 nm to 5000 nm.

17. The tip array of claim 1, wherein the plurality of tips are disposed with a tip-to-tip spacing in a range of 1 μ

to 10 mm.

18. The tip array of claim 1, wherein each tip has a radius of curvature of less than 0.2 μ

m.

19. The tip array of claim 1, wherein the tip substrate layer and tips comprise a polymer having a compression modulus of 10 MPa to 300 MPa.

20. The tip array of claim 1, further comprising at least one spatial light modulator disposed on the tip substrate layer.

21. The tip array of claim 20, wherein the spatial light modulator is dynamically controllable.

22. The tip array of claim 1, further comprising an array of spatial light modulators disposed on the tip substrate layer.

23. A method for sub-micron scale patterning, comprising:

contacting a photosensitive substrate with a tip array of claim 1;

irradiating at least one tip of the tip array with a radiation source, to transmit radiation through the tip and out the tip end; and

exposing a portion of the photosensitive substrate with the transmitted radiation.

24. The method of claim 23, wherein the exposed area of the photosensitive substrate has a dot size (or line width) of less than 1μ

m.

25. The method of claim 23, comprising irradiating all of the tips in the tip array.

26. The method of claim 23, comprising selectively masking the tip substrate layer to selectively illuminating at least one tip.

27. The method of claim 23, further comprising moving the tip array, the substrate surface, or both after said contacting step and then repeating the contacting step.

28. The method of claim 24, wherein the dot size (or line width) is less than 100 nm.

29. The method of claim 23, comprising irradiating with radiation having a wavelength in a range of 10 nm to 500 nm.

30. The method of claim 23, wherein the photosensitive substrate comprises a photosensitive layer disposed on a substrate layer.

31. The method of claim 23, wherein the photosensitive substrate comprises a resist material.

32. The method of claim 23, further comprising developing the exposed photosensitive substrate to remove either the exposed portion of the photosensitive substrate or the non-exposed portion of the photosensitive substrate, applying a patterning material to the portion of the substrate in which the photosensitive substrate was removed;

and removing the remaining portion of the photosensitive substrate to thereby leave an indicium.

33. The method of claim 32, wherein said indicium has a dot size (or line width) of less than 1 μ

m.

34. The method of claim 32, wherein the patterning material is a metal.

35. The method of claim 34, comprising applying the patterning material by metal evaporation.

36. A method of making a beam pen lithography tip array of claim 1, comprising:

providing tip array comprising a tip substrate layer comprising a first surface, an oppositely disposed second surface, a plurality of tips fixed to the first surface, the tips each comprising a tip end disposed opposite the first surface;

coating a blocking layer on the plurality of tips and the first surface; and

forming an aperture in the blocking layer at the tip ends of the tips by removing a portion of the blocking layer.

37. The method of claim 36, comprising forming the tip array by

providing a master comprising an array of recesses in a substrate separated by lands;

filling the recesses and covering the lands with a prepolymer mixture comprising a prepolymer and, optionally, a crosslinker;

curing the prepolymer mixture to form a transparent polymer structure;

separating the cured polymer structure from the master.

38. The method of claim 36, comprising removing the portion of the blocking layer by contacting the coated portion of polymer structure to a surface coated with an adhesive, and then moving the coated polymer structure away from the adhesive to separate an adhered portion of the blocking layer from the cured polymer structure.

39. The method of claim 36, comprising removing the portion of the blocking layer by coating the blocking layer with an adhesive;

removing at least a portion of the adhesive by contacting the coated polymer structure to a surface, wherein upon removal of the polymer structure from the surface, the contacted portion of the adhesive remains on the surface to define an opening in the adhesive, exposing a portion of the blocking layer; and

etching the exposed portion of the blocking layer and thereby exposing a portion of the polymer structure.

40. The method of claim 37, further comprising forming the recesses as pyramidal recesses by forming wells in the substrate and anisotropically wet-etching the substrate.

41. The method of claim 37, further comprising covering the filled and coated substrate with a planar glass layer prior to curing.

42. The method of claim 38 comprising use of an adhesive, wherein the adhesive is selected from the group consisting of PMMA, PEG, poly(acrylonitrile), and combinations thereof.

43. The method of claim 38 comprising use of an adhesive, comprising controlling the diameter of the aperture by controlling the contact pressure between the polymer structure and the surface.

44. A system for beam pen lithography, comprising:

a radiation source for emitting a radiation in a path;

a tip array of claim 1 disposed in the radiation path such that the radiation, when active, is incident upon the tip substrate layer; and

a substrate stage disposed for selective contacting of a substrate to the tip array.

45. The system of claim 44, wherein the substrate stage comprises a piezo stage.

46. The system of claim 44, further comprising at least one spatial light modulator disposed in the radiation path between the radiation source and the tip array.

47. The system of claim 46, further comprising an array of spatial light modulators disposed in the radiation path between the radiation source and the tip array.

48. The system of claim 47, wherein each spatial light modulator is individually controllable to selectively pass or reflect incident radiation from the radiation source.

49. The system of claim 46 comprising a plurality of spatial light modulators, wherein the spatial light modulators are dynamically controllable.

50. A tip array comprising:

a tip substrate layer comprising a first surface and an oppositely disposed second surface, the tip substrate layer being formed from an at least translucent substrate layer material that extends between the first surface and the second surface;

a plurality of tips fixed to the first surface, the tips each comprising a tip end disposed opposite the first surface, the plurality of tips being formed from an at least translucent and deformable tip material that extends from the first surface to the tip end, the tips having a radius of curvature of less than 1 μ

m, wherein the tips are arranged in a pre-determined pattern extending in at least two dimensions;

a blocking layer coated on the plurality of tips and the first surface; and

a plurality of apertures defined in the blocking layer exposing the tip ends of the plurality of tips,

wherein the tip array is configured to generate a near field optical effect when brought in proximity with a substrate, and deformation of the tips when in contact with the substrate provides a change in the size of the near-field optical effect.