POLYMER PEN LITHOGRAPHY

• US 20110132220A1
• Filed: 04/25/2009
• Published: 06/09/2011
• Est. Priority Date: 04/25/2008
• Status: Active Grant

• Current Assignee: Northwestern University
• Original Assignee: Northwestern University
• Inventors: Zheng, Zijian, Huo, Fengwei, Zheng, Gengfeng, Mirkin, Chad A.
• Granted Patent: US 9,372,397 B2
• Time in Patent Office: Days
• US Class Current: 101/483
• 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 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• 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: Y10S 977/856 including etching/cutting
• CPC Class Codes: Y10S 977/874 Probe tip array
• CPC Class Codes: Y10S 977/878 Shape/taper
• CPC Class Codes: Y10S 977/887 Nanoimprint lithography, i.e. nanostamp
• CPC Class Codes: Y10S 977/888 Shaping or removal of materials, e.g. etching
• CPC Class Codes: Y10S 977/902 Specified use of nanostructure

Abstract

The disclosure relates to methods of printing indicia on a substrate using a tip array comprised of elastomeric, compressible polymers. The tip array can be prepared using conventional photolithographic methods and can be tailored to have any desired number and/or arrangement of tips. Numerous copies (e.g., greater than 15,000, or greater than 11 million) of a pattern can be made in a parallel fashion in as little as 40 minutes.

Claims

1. A method for sub-micron scale printing of indicia on a substrate surface, comprising:

coating a tip array with a patterning composition, the tip array comprising a compressible elastomeric polymer comprising a plurality of non-cantilevered tips each having a radius of curvature of less than about 1 μ

m;

contacting the substrate surface for a first contacting period of time and at a first contacting pressure with all or substantially all of the coated tips of the array to deposit the patterning composition onto the substrate surface and form substantially uniform indicia with all or substantially all of said coated tips, the indicia having a dot size (or line width) of less than 1 μ

m.

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

3. The method of claim 1, wherein each tip has a radius of curvature of less than about 0.2 μ

m.

4. The method of claim 1, wherein the polymer has a compression modulus of about 10 MPa to about 300 MPa.

5. The method of claim 1, wherein the polymer is crosslinked.

6. The method of claim 1, wherein the polymer comprises polydimethylsiloxane (PDMS).

7. The method of claim 6, wherein the PDMS comprises a trimethylsiloxy terminated vinylmethylsiloxane-dimethysiloxane copolymer, a methylhydrosiloxane-dimethylsiloxane copolymer, or a mixture thereof.

8. The method of claim 1, wherein each tip of the tip array is identically-shaped.

9. The method of claim 8, wherein the tip shape is pyramidal.

10. The method of claim 1, wherein the coating comprises adsorbing or absorbing the patterning composition onto the tip array.

11. The method of claim 1, further comprising moving the tip array, the substrate surface, or both and repeating the contacting step for a second contacting period of time and at a second contacting pressure.

12. The method of claim 11, wherein the first contacting period of time and the second contacting period of time are equal.

13. The method of claim 11, wherein the first contacting period of time and the second contacting period of time are different.

14. The method of claim 11, wherein the first contacting pressure and the second contacting pressure are the same.

15. The method of claim 11, wherein the first contacting pressure and the second contacting pressure are different.

16. The method of claim 1, further comprising controlling a z-piezo of a piezo scanner upon which the substrate or the tip array is mounted to control the contacting pressure.

17. The method of claim 11, comprising moving the tip array and holding the substrate surface stationary.

18. The method of claim 11, comprising holding the tip array stationary and moving the substrate surface.

19. The method of claim 11, comprising moving both the tip array and the substrate surface.

20. The method of claim 1, comprising limiting lateral movement between the tip array and the substrate to form indicia comprising dots.

21. The method of claim 20, comprising controlling the contacting period of time, the contacting pressure, or both to form the dots with a diameter in a range of about 10 nm to about 500 μ

m.

22. The method of claim 1, comprising controlling lateral movement between the tip array and the substrate surface during contacting and/or between one or more sets of contacting and depositing steps to form indicia comprising one or more of lines and a preselected pattern.

23. The method of claim 1, comprising selecting for the tip array a compressible polymer which is Hookean under pressures of 10 MPa to 300 MPa.

24. The method of any claim 1, comprising contacting each tip of the tip array with the substrate surface.

25. The method of claim 1, wherein the indicia have a dot size (or line width) of less than 900 nm.

26. The method of claim 1, wherein the indicia have a dot size (or line width) of less than 100 nm.

27. The method of claim 1, further comprising leveling the tips of the tip array with respect to the substrate surface by

backlighting the tip array with incident light to cause internal reflection of the incident light from the internal surfaces of the tips;

bringing the tips of the tip array and the substrate surface together along a z-axis up to a point of contact between a subset of the tips with the substrate surface, contact indicated by increased intensity of reflected light from the subset of tips in contact with the substrate surface, whereas no change in the intensity of reflected light from other tips indicates non-contacting tips; and

tilting one or both of the tip array and the substrate surface with respect to the other in response to differences in intensity of the reflected light from the internal surfaces of the tips, to achieve contact between the substrate surface and non-contacting tips,

wherein said tilting is performed one or more times along x-, y-, and/or z-axes.

28. The method of claim 1, further comprising leveling the tips of the tip array with respect to the substrate surface by

backlighting the tip array with incident light to cause internal reflection of the incident light from the internal surfaces of the tips;

bringing the tips of the tip array and the substrate surface together along a z-axis to cause contact between the tips of the tip array and the substrate surface;

further moving one or both of the tip array and the substrate towards the other along the z-axis to compress a subset of the tips, whereby the intensity of the reflected light from the tips increases as a function of the degree of compression of the tips against the substrate surface; and

tilting one or both of the tip array and the substrate surface with respect to the other in response to differences in intensity of the reflected light from internal surfaces of the tips, to achieve substantially uniform contact between the substrate surface and tips, wherein said tilting is performed one or more times along x-, y- and/or z-axes.

29. A tip array comprising a plurality of tips fixed to a common substrate layer, the tips and common substrate layer formed from an elastomeric polymer, the elastomeric polymer of the tips having a compression modulus of about 10 MPa to about 300 MPa, and each tip having a radius of curvature of less than about 1 μ

m.

30. The tip array of claim 29, wherein each tip has a radius of curvature of less than about 0.5 μ

m.

31. The tip array of claim 30, wherein each tip has a radius of curvature of less than about 100 nm.

32. The tip array of claim 29, wherein the tips are arranged in a regular periodic pattern.

33. The tip array of claim 29, wherein the tips are identically-shaped.

34. The tip array of claim 29, wherein the tips are pyramidal.

35. The tip array of claim 29, wherein the thickness of the common substrate layer is about 50 μ

m to about 100 μ

m.

36. The tip array of claim 29, further comprising a rigid support to which the common substrate is adhered.

37. The tip array of claim 29, wherein the tip array, common substrate layer, and rigid support are at least translucent.

38. The tip array of claim 29, wherein the common substrate layer and tips have a combined thickness of less than about 200 μ

m.

39. The tip array of claim 38, wherein the combined thickness is less than about 150 μ

m.

40. The tip array of claim 39, wherein the combined thickness is about 100 μ

m.

41. A tip array comprising a plurality of tips fixed to a common substrate layer, the tips and common substrate layer formed from an elastomeric polymer, each tip having a radius of curvature of less than about 1 μ

m and the common substrate layer and tips having a combined thickness of less than about 200 μ

m.

42. A tip array comprising an at least translucent stacked structure comprising a plurality of tips fixed to a common elastomeric polymer substrate, the substrate fixed to a glass slide.

43. A method of making a tip array, comprising:

forming 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 an prepolymer and, optionally, a crosslinker;

curing the prepolymer mixture to form a polymer structure; and

separating the polymer structure from the master.

44. The method of claim 43, further comprising forming the recesses as pyramidal recesses by forming wells in the substrate and anisotropicaly wet-etching the substrate.

45. The method of claim 43, further comprising covering the filled and coated substrate with a planar glass layer prior to curing.