NON-CONTACT TRANSFER PRINTING

• US 20130036928A1
• Filed: 07/13/2012
• Published: 02/14/2013
• Est. Priority Date: 07/14/2011
• Status: Active Grant

• Current Assignee: Board of Trustees of The University of Illinois
• Original Assignee: John A. Rogers, Placid M. Ferreira
• Inventors: ROGERS, John A., FERREIRA, Placid M., SAEIDPOURAZAR, Reza
• Granted Patent: US 9,555,644 B2
• Time in Patent Office: Days
• US Class Current: 101/483
• CPC Class Codes: B41F 16/00 Transfer printing apparatus
• CPC Class Codes: B41J 2/475 for heating selectively by radiation or ultrasonic waves
• CPC Class Codes: B41M 2205/08 Ablative thermal transfer, i.e. the exposed transfer medium is propelled from the donor to a receptor by generation of a gas
• CPC Class Codes: B41M 5/382 Contact thermal transfer or sublimation processes sublistatic printing using a pre-formed image B41M5/035; ink-, dye- or pigment-receptive coatings B41M5/52

Abstract

A transfer printing process that exploits the mismatch in mechanical or thermo-mechanical response at the interface of a printable micro- or nano-device and a transfer stamp to drive the release of the device from the stamp and its non-contact transfer to a receiving substrate are provided. The resulting facile, pick-and-place process is demonstrated with the assembling of 3-D microdevices and the printing of GAN light-emitting diodes onto silicon and glass substrates. High speed photography is used to provide experimental evidence of thermo-mechanically driven release.

Claims

1. A method of transferring ink from a donor substrate to a receiving substrate, said method comprising:

providing a transfer device having a transfer surface;

providing said donor substrate having a donor surface, said donor surface having ink thereon;

contacting at least a portion of said transfer surface with at least a portion of said ink;

separating said transfer surface from said donor surface, wherein at least a portion of said ink is transferred from said donor surface to said transfer surface;

positioning said transfer surface having said ink disposed thereon into alignment with a receiving surface of said receiving substrate, wherein a gap remains between said ink disposed on said transfer surface and said receiving surface; and

actuating said transfer device, said ink, or both of said transfer device and said ink by generating a force that releases at least a portion of said ink from said transfer surface while maintaining at least a portion of said gap, thereby transferring at least a portion of said ink to said receiving surface.

2. The method of claim 1, wherein said step of actuating comprises mechanically actuating, optically actuating, electrically actuating, magnetically actuating, thermally actuating, or a combination thereof.

3. The method of claim 1, wherein said step of actuating said transfer device uses a laser, a piezoelectric actuator, a gas source, a vacuum source, an electromagnetic source, an electrostatic source, an electronic source, a heat source, or a combination thereof.

4. The method of claim 3, wherein said gas source directs a flow or burst of gas onto said transfer device or said ink disposed on said transfer surface of said transfer device, thereby mechanically actuating said transfer device, said ink or both.

5. The method of claim 4, wherein said gas source directs said flow or burst of gas through one or more channels or reservoirs in said transfer device onto said ink, thereby generating said force that releases at least a portion of said ink from said transfer surface.

6. The method of claim 5, wherein said gas source produces gas having a pressure selected from the range of 5 psi to 100 psi.

7. The method of claim 5, wherein said gas is produced for a period selected from the range of 1 millisecond to 10 milliseconds.

8. The method of claim 3, wherein said vacuum source is provided in fluid communication with said transfer device, said ink or both such that said vacuum source produces a pressure on said transfer device, said ink or both, thereby generating said force that releases at least a portion of said ink from said transfer surface.

9. The method of claim 8, wherein said pressure is selected from the range of 10⁻

3 torr to 10<sup>−

5</sup> torr.

10. The method of claim 3, wherein said electromagnetic source is provided in optical communication with said transfer device, said ink or both and provides electromagnetic radiation onto said transfer device, said ink disposed on said transfer device or both.

11. The method of claim 10, wherein said electromagnetic radiation has a wavelength selected from the range of 300 μ

m to 5 μ

m.

12. The method of claim 10, wherein said electromagnetic radiation has a power selected from the range of 10 W to 100 W.

13. The method claim 10, wherein said electromagnetic radiation is characterized by a pulse width selected over the range of 100 μ

s and 10 milliseconds.

14. The method of claim 10, wherein said electromagnetic radiation is characterized by a focused beam spot having an area selected from the range of 150 μ

m² to 1 mm².

15. The method of claim 10, wherein said electromagnetic radiation delivers less than 0.5 mJ of energy to said ink.

16. The method of claim 10, wherein said electromagnetic radiation is spatially translated on said transfer surface of said transfer device at a rate of at least 50 mm/sec.

17. The method of claim 3, wherein said electrostatic source generates an applied electric field on said transfer surface, said ink disposed on said transfer surface, or both.

18. The method of claim 3, wherein said heat source heats said transfer device, said ink, or both of said transfer device and said ink, thereby thermally actuating said transfer device, said ink, or both of said transfer device and said ink.

19. The method of claim 18, wherein said heat source produces a temperature of said transfer surface selected from the range of 275°

C. to 325°

C.

20. The method of claim 18, wherein said heat source produces a temperature gradient in said transfer device selected from the range of 10⁴°

C. cm<sup>−

1</sup> to 10⁵°

C. cm<sup>−

1</sup>.

21. The method of claim 3, wherein said piezoelectric actuator physically contacts said transfer surface of said transfer device, thereby electrically actuating said ink.

22. The method of claim 1, wherein the magnitude and spatial distribution of said force is selected so as to generate a separation energy between said ink and said transfer surface equal to or greater than 1 J/meter².

23. The method of claim 1, wherein said force is a non-ablative force.

24. The method of claim 1, wherein said force does not substantially degrade said transfer device.

25. The method of claim 1, wherein said step of actuating comprises mechanically stressing an interface between said transfer surface and said ink so as to cause delamination, thereby resulting in release of said ink.

26. The method of claim 1, wherein said step of actuating induces a thermomechanical force at an interface between said ink and said transfer surface resulting in delamination of said ink from said transfer surface, thereby resulting in release of said ink from said transfer surface.

27. The method of claim 26, wherein said delamination begins at a corner of said ink and propagates toward a center of said ink, thereby resulting in release of said ink from said transfer surface.

28. The method of claim 1, wherein said ink has a coefficient of thermal expansion selected from the range of 1 ppm °

C.<sup>−

1</sup> to 10 ppm °

C.<sup>−

1</sup>.

29. The method of claim 1, wherein said ink has a Young'"'"'s modulus selected from the range of 10 GPa to 500 GPa.

30. The method of claim 1, wherein said transfer device and said ink have a ratio of coefficients of thermal expansion selected from the range of 500 to 2.

31. The method of claim 1, wherein said transfer device and said ink have a ratio of Young'"'"'s moduli selected from the range of 10 to 100.

32. The method of claim 1, wherein said gap is characterized by a distance between said ink disposed on said transfer surface and said receiving surface equal to or great than 1 micrometer.

33. The method of claim 1, wherein said gap is characterized by a distance between said ink disposed on said transfer surface and said receiving surface equal to or less than 50 micrometers.

34. The method of claim 1, wherein said gap is characterized by a distance between said ink disposed on said transfer surface and said receiving surface selected from the range of 1 micrometer to 50 micrometers.

35. The method of claim 1, wherein said ink is transferred to said receiving surface with a placement accuracy greater than or equal to 25 microns over a receiving surface area equal to 5 cm².

36. The method of claim 1, wherein said ink is a material selected from the group consisting of a semiconductor, a metal, a dielectric, a ceramic, a polymer, a glass, a biological material or any combination of these.

37. The method of claim 1, wherein said ink is a micro-sized or nano-sized prefabricated device or component thereof.

38. The method of claim 37, wherein said prefabricated device is a printable semiconductor element.

39. The method of claim 37, wherein said prefabricated device is a single crystalline semiconductor structure.

40. The method of claim 37, wherein said prefabricated device has a shape selected from the group consisting of a ribbon, a disc, a platelet, a block, a column, a cylinder, and any combination thereof.

41. The method of claim 37, wherein said prefabricated device is a single crystalline semiconductor device.

42. The method of claim 37, wherein said prefabricated device comprises an electronic, optical or electro-optic device or a component of an electronic, optical or electro-optic device selected from the group consisting of:

a P-N junction, a thin film transistor, a single junction solar cell, a multi-junction solar cell, a photodiode, a light emitting diode, a laser, a CMOS device, a MOSFET device, a MESFET device, a HEMT device, a photovoltaic device, a sensor, a memory device, a microelectromechanical device, a nanoelectromechanical device, a complementary logic circuit, and a wire.

43. The method of claim 1, wherein said ink has a length selected over the range of 100 nanometers to 1000 microns, a width selected over the range of 100 nanometers to 1000 microns and a thickness selected over the range of 1 nanometer to 1000 microns.

44. The method of claim 1, wherein a contact surface of said ink is provided in physical contact with said transfer device, wherein the contact surface has a surface area selected over the range of 10⁶ nm² to 1 mm².

45. The method of claim 37, further comprising a step of providing a plurality of prefabricated devices.

46. The method of claim 45, wherein substantially all of said prefabricated devices are transferred from said donor surface to said transfer surface simultaneously.

47. The method of claim 45, wherein substantially all of said prefabricated devices in contact with said transfer surface are transferred to said receiving surface simultaneously.

48. The method of claim 45, wherein substantially all of said prefabricated devices in contact with said transfer surface are transferred to said receiving surface one at a time.

49. The method of claim 1, further comprising repeating at least a portion of said steps so as to generate multi-layered ink structures on said receiving surface.

50. The method of claim 49, wherein said multi-layered ink structure is three-dimensional and at least some of said ink is deposited onto previously deposited ink.

51. The method of claim 1, wherein said transfer device comprises at least one elastomer layer having a Young'"'"'s modulus selected over the range of 1 MPa to 10 GPa.

52. The method of claim 1, wherein said transfer device comprises at least one elastomer layer having a thickness selected over the range of 1 micron to 1000 microns.

53. The method of claim 1, wherein said transfer device has a coefficient of thermal expansion selected from the range of 100 ppm °

C.<sup>−

1</sup> to 500 ppm °

C.<sup>−

1</sup>.

54. The method of claim 1, wherein said transfer device comprises at least one elastomer layer operably connected to one or more polymer, glass or metal layers.

55. The method of claim 1, wherein said transfer device comprises an elastomeric stamp, elastomeric mold, or elastomeric mask.

56. The method of claim 1, wherein said transfer device comprises a material selected from the group consisting of glass and silica.

57. The method of claim 1, wherein said transfer device is an elastomeric transfer device.

58. The method of claim 1, wherein said transfer device comprises polydimethylsiloxane.

59. The method of claim 1, wherein said transfer device is at least partially transparent to electromagnetic radiation having wavelengths in ultraviolet, visible or infrared regions of the electromagnetic spectrum.

60. The method of claim 1, wherein said transfer device is substantially planar.

61. The method of claim 1, wherein said transfer surface of said transfer device is microstructured or nanostructured.

62. The method of claim 1, wherein said transfer device comprises at least one relief feature having a surface for contacting said ink.

63. The method of claim 62, wherein said relief feature extends at least 5 micrometers from said transfer surface.

64. The method of claim 62, wherein said relief feature has a cross-sectional area perpendicular to a longitudinal axis of the relief feature, said cross-sectional area having a major dimension that is less than or equal to 1000 micrometers.

65. The method of claim 62, further comprising a layer of absorbing material encapsulated within said relief feature, said layer positioned between 1 micrometer and 100 micrometers from a distal end of said relief feature and substantially equidistant from said surface of said relief feature.

66. The method of claim 65, wherein said absorbing material is selected from the group consisting of silicon, graphite, carbon black and a metal.

67. The method of claim 1, wherein said transfer device comprises a plurality of relief features forming an array and having surfaces for contacting said ink.

68. The method of claim 67, wherein each relief feature in said array is separated from any other relief feature in said array by a distance of 3 micrometers to 100 millimeters.

69. The method of claim 1, wherein said receiving substrate is a material selected from the group consisting of:

a polymer, a semiconductor wafer, a ceramic material, a glass, a metal, paper, a dielectric material, a liquid, a biological cell, a hydrogel and any combination of these.

70. The method of claim 1, wherein said receiving surface is planar, rough, charged, neutral, non-planar, or contoured.

71. The method of claim 1, wherein placement accuracy of said transfer method is independent of the shape, composition and surface contour of said receiving substrate.

72. The method of claim 1, wherein said ink adheres directly to said transfer surface.

73. The method of claim 1, further comprising a step of providing an absorbing material between said ink and said transfer surface.

74. The method of claim 73, wherein said absorbing material is applied to said ink prior to said step of contacting at least a portion of said transfer surface with at least a portion of said ink, and wherein said absorbing material is removed after said step of applying a force to said transfer surface.

75. The method of claim 73, wherein said absorbing material is a thermal adhesive or a photoactivated adhesive.

76. The method of claim 73, where said absorbing material has a coefficient of thermal expansion selected from the range of 300 ppm °

C.<sup>−

1</sup> to 1 ppm °

C.<sup>−

1</sup>.

77. The method of claim 73, where said absorbing material has a Young'"'"'s modulus selected from the range of 100 MPa to 500 GPa.

78. The method of claim 73, wherein said absorbing material has a thickness selected from the range of 2 microns to 10 microns.

79. The method of claim 73, wherein said absorbing material is selected from the group consisting of silicon, graphite, carbon black, metals with nanostructured surfaces, and combinations thereof.

80. The method of claim 1, wherein said steps are repeated using a single transfer device between 20-25 times before substantial degradation of said transfer device is detectable.

81. The method of claim 1, wherein said steps of:

contacting at least a portion of said transfer surface with at least a portion of said ink, separating said transfer surface from said donor surface, positioning said transfer surface, or any combination of these steps is carried out via an actuator operationally connected to said transfer device.

82. The method of claim 1, wherein said step of positioning said transfer surface having said ink disposed thereon into alignment with said receiving surface provides said transfer surface in proximity to selected regions of said receiving surface.

83. The method of claim 1, wherein said step of positioning said transfer surface having said ink disposed thereon into alignment with said receiving surface provides registration between said ink and selected regions of said receiving surface.

84. The method of claim 82, wherein said selected regions of said receiving surface correspond to devices or device components prepositioned on said receiving surface of said receiving substrate.

85. The method of claim 82, wherein said proximity is to within 5 μ

m or less.