PATTERNING METHODS FOR STRETCHABLE STRUCTURES

• US 20100143848A1
• Filed: 12/09/2008
• Published: 06/10/2010
• Est. Priority Date: 12/09/2008
• Status: Active Grant

• Current Assignee: Board of Trustees of The University of Illinois
• Original Assignee: Board of Trustees of The University of Illinois
• Inventors: Lin, Kevin, Jain, Kanti
• Granted Patent: US 8,187,795 B2
• Time in Patent Office: Days
• US Class Current: 430/315
• CPC Class Codes: B23K 2103/172 wherein at least one of the layers is non-metallic
• CPC Class Codes: B23K 26/40 taking account of the properties of the material involved
• CPC Class Codes: B81B 2201/0292 Sensors not provided for in B81B2201/0207 - B81B2201/0285
• CPC Class Codes: B81B 2203/0109 Bridges
• CPC Class Codes: B81B 2207/07 Interconnects
• CPC Class Codes: B81C 1/0019 Flexible or deformable structures not provided for in groups B81C1/00142 - B81C1/00182
• CPC Class Codes: H05K 1/0283 Stretchable printed circuits
• CPC Class Codes: H05K 2201/09109 Locally detached layers, e.g. in multilayer
• CPC Class Codes: H05K 2203/0554 Metal used as mask for etching vias, e.g. by laser ablation
• CPC Class Codes: H05K 2203/308 Sacrificial means, e.g. for temporarily filling a space for making a via or a cavity or for making rigid-flexible PCBs
• CPC Class Codes: H05K 3/0032 of organic insulating material
• CPC Class Codes: H05K 3/007 Manufacture or processing of a substrate for a printed circuit board supported by a temporary or sacrificial carrier H05K1/187, H05K3/20 and H05K3/4682 take precedence

Abstract

Described herein are processing techniques for fabrication of stretchable and/or flexible electronic devices using laser ablation patterning methods. The laser ablation patterning methods utilized herein allow for efficient manufacture of large area (e.g., up to 1 mm² or greater or 1 m² or greater) stretchable and/or flexible electronic devices, for example manufacturing methods permitting a reduced number of steps. The techniques described herein further provide for improved heterogeneous integration of components within an electronic device, for example components having improved alignment and/or relative positioning within an electronic device. Also described herein are flexible and/or stretchable electronic devices, such as interconnects, sensors and actuators.

Claims

1. A method of making an electronic device, the method comprising the steps of:

providing a flexible substrate;

depositing a first metal layer on the flexible substrate;

patterning the first metal layer, thereby generating a first patterned metal layer that exposes one or more regions of exposed flexible substrate; and

exposing the first patterned metal layer and the exposed flexible substrate to ablation radiation to ablate at least a portion of the flexible substrate, wherein the first patterned metal layer functions as an in situ ablation mask and provides a structural component of the electronic device.

2. The method of claim 1, wherein the ablation radiation does not significantly ablate the first patterned metal layer during the exposing step.

3. The method of claim 1, wherein the ablation radiation does not significantly damage the first patterned metal layer during the exposing step.

4. The method of claim 1, wherein the exposing step ablates substantially all of the regions of exposed flexible substrate.

5. The method of claim 1, wherein the first patterned metal layer is a self-aligned ablation mask for ablation patterning at least a portion of the flexible substrate.

6. The method of claim 1, further comprising the steps of:

providing a dielectric layer on at least a portion of the first patterned metal layer and at least a portion of the exposed flexible substrate;

depositing a second metal layer on the dielectric layer; and

patterning the second metal layer, thereby generating a second patterned metal layer that exposes regions of exposed dielectric;

wherein the exposing step includes exposing the exposed dielectric to ablation radiation to ablate at least a portion of the dielectric layer, wherein the first and second patterned metal layers function as an in situ ablation mask and provide structural components of the electronic device.

7. The method of claim 6, further comprising repeating one or more times the steps of:

providing an additional dielectric layer on at least a portion of the topmost patterned metal layer and at least a portion of the exposed dielectric layer;

depositing an additional metal layer on the additional dielectric layer; and

patterning the additional metal layer, thereby generating an additional patterned metal layer that exposes regions of exposed dielectric;

wherein the exposing step includes exposing the exposed dielectric to ablation radiation to ablate at least a portion of the dielectric layer, and wherein the patterned metal layers function as in situ ablation masks and provide structural components of the electronic device.

8. The method of claim 6, wherein the ablation radiation does not significantly ablate the first and second patterned metal layers during the exposing step.

9. The method of claim 6, wherein the ablation radiation does not significantly damage the first and second patterned metal layers during the exposing step.

10. The method of claim 6, wherein the first and second second patterned metal layers are self-aligned ablation masks for ablation patterning at least a portion of the dielectric layer.

11. The method of claim 6, wherein the first and second patterned metal layers are self-aligned ablation masks for ablation patterning at least a portion of the flexible substrate.

12. The method of claim 6, wherein the exposing step ablates substantially all of the regions of exposed dielectric layer.

13. The method of claim 6, wherein the exposing step ablates substantially all of the regions of exposed flexible substrate.

14. The method of claim 1, wherein the flexible substrate is a polymer substrate.

15. The method of claim 14, wherein the flexible substrate is an elastomer substrate.

16. The method of claim 14, wherein the polymer substrate comprises a material selected from the group consisting of polymethylmethacrylate (PMMA), polyimide, polyethylene terephathalate (PET), polystyrene, polycarbonate, polyvinyl alcohol (PVA), polybenzimidazole, tetrafluoroethylene, SU-8, parylene, polyester, poly-dimethyl-siloxane (PDMS) and any combination of these.

17. The method of claim 14, wherein the polymer substrate has a thickness selected over the range of 5 μ

m to 1000 μ

m.

18. The method of claim 1, wherein regions of the exposed flexible substrate have areas selected over the range of 1 mm² to 1 m².

19. The method of claim 1, wherein the first metal layer comprises a metal selected from the group consisting of aluminum, copper, chromium, nickel, titanium, tungsten, gold, tin, zinc, molybdenum, silver, lead, indium, iron, platinum, and any metal alloy.

20. The method of claim 1, wherein the first metal layer has a thickness selected over the range of 100 nm to 5 μ

m.

21. The method of claim 1, wherein at least one metal layer is replaced by a layer comprising an inorganic dielectric.

22. The method of claim 21, wherein the inorganic dielectric is selected from the group consisting of silicon dioxide, silicon nitride and aluminum oxide.

23. The method of claim 1, wherein at least one metal layer is replaced by a layer comprising a semiconductor.

24. The method of claim 23, wherein the semiconductor is selected from the group consisting of Silicon, Germanium, Gallium Arsenide and Indium Phosphide.

25. The method of claim 6, wherein the dielectric layer comprises a material selected from the group consisting of spin-on polymers, polyimide, SU-8 and any combination of these.

26. The method of claim 1, wherein the dielectric layer has a thickness selected over the range of 100 nm to 10 μ

m.

27. The method of claim 1, wherein the exposing step is carried out using a fluence of the ablation radiation selected over the range of 30 mJ/cm² to 500 mJ/cm².

28. The method of claim 1, wherein the exposing step is carried out using the ablation radiation having wavelengths selected over the range of 100 nm to 400 nm.

29. The method of claim 1, wherein the ablation radiation is excimer laser radiation, ion laser radiation, or frequency-multiplied solid state laser radiation.

30. A method of making a capacitive sensor, the method comprising the steps of:

providing a polymer substrate;

depositing a first metal layer one the polymer substrate;

patterning the first metal layer, thereby generating a first patterned metal layer that exposes one or more regions of exposed polymer substrate; and

providing a sacrificial layer on at least a portion of the first patterned metal layer and at least a portion of the exposed polymer substrate;

patterning the sacrificial layer;

providing a dielectric layer on at least a portion of the sacrificial layer, the first patterned metal layer and the exposed polymer substrate;

depositing a second metal layer on the dielectric layer;

patterning the second metal layer, thereby generating a second patterned metal layer that exposes one or more regions of exposed dielectric layer;

exposing the second patterned metal layer, the regions of exposed dielectric layer, the sacrificial layer, the first patterned metal layer and the exposed polymer substrate to ablation radiation to ablate at least a portion of the dielectric layer and at least a portion of the polymer substrate; and

wherein the first patterned metal layer and the second patterned metal layer function as in situ ablation masks and provide structural components of the capacitive sensor; and

removing the sacrificial layer.

31. The method of claim 30, wherein the ablation radiation does not significantly ablate the first patterned metal layer or the second patterned metal layer during the exposing step.

32. The method of claim 30, wherein the ablation radiation does not significantly damage the first patterned metal layer or the second patterned metal layer during the exposing step.

33. The method of claim 30, wherein the exposing step ablates substantially all of the regions of exposed polymer substrate and substantially all the regions of exposed dielectric layer.

34. The method of claim 30, wherein the first patterned metal layer and the second patterned metal layer are self-aligned ablation masks.

35. The method of claim 30, wherein the sacrificial layer has a thickness selected over the range of 100 nm to 50 μ

m.

36. The method of claim 30, wherein the sacrificial layer comprises a material selected from the group consisting of photoresist, polymer, metal oxide and dielectric.

37. The method of claim 30, wherein the sacrificial layer comprises a material which can be removed without damaging the polymer substrate, the patterned metal layers, or the dielectric layers.

38. The method of claim 30, wherein the sacrificial layer is removed by dissolution.

39. The method of claim 30, wherein the sacrificial layer is removed by exposure to a fluid selected from the group consisting of:

a solvent, an acid solution and an alkaline solution.

40. The method of claim 30, wherein the first metal layer has a thickness selected over the range of 100 nm to 5 μ

m, the second metal layer has a thickness selected over the range of 100 nm to 5 μ

m and the dielectric layer has a thickness selected over the range of 100 nm to 50 μ

m.

41. The method of claim 30, wherein the polymer substrate comprises a material selected from the group consisting of polymethylmethacrylate (PMMA), polyimide, polyethylene terephathalate (PET), polystyrene, polycarbonate, polyvinyl alcohol (PVA), polybenzimidazole, tetrafluoroethylene, SU-8, parylene, polyester, poly-dimethyl-siloxane (PDMS) and any combination of these.

42. The method of claim 30, wherein the polymer substrate has a thickness selected over the range of 10 μ

m to 1000 μ

m.

43. The method of claim 30, further comprising repeating one or more times the steps of:

providing an additional dielectric layer on at least a portion of the topmost layer;

depositing an additional metal layer on the additional dielectric layer; and

patterning the additional metal layer, thereby generating an additional patterned metal exposing regions of the additional dielectric layer;

wherein the exposing step includes exposing the exposed dielectric to ablation radiation to ablate at least a portion of the dielectric layer, and wherein the patterned metal layers function as in situ ablation masks and provide structural components of the electronic device.

44. The method of claim 30, wherein at least one metal layer is replaced by a layer comprising an inorganic dielectric.

45. The method of claim 44, wherein the inorganic dielectric is selected from the group consisting of silicon dioxide, silicon nitride and aluminum oxide.

46. The method of claim 30, wherein at least one metal layer is replaced by a layer comprising a semiconductor.

47. The method of claim 46, wherein the semiconductor is selected from the group consisting of Silicon, Germanium, Gallium Arsenide and Indium Phosphide.

48. A method of making a sensor, the method comprising the steps of:

providing a polymer substrate;

providing a sacrificial layer on the polymer substrate;

providing a dielectric layer on the sacrificial layer;

depositing a metal layer on the dielectric layer;

patterning the metal layer, thereby generating a patterned metal layer that exposes one or more regions of the dielectric layer;

exposing the patterned metal layer and the regions of exposed dielectric layer to ablation radiation to ablate at least a portion of the dielectric layer, wherein the patterned metal layer functions as an in situ ablation mask and provides a structural component of the sensor; and

removing the sacrificial layer.

49. The method of claim 48, wherein the ablation radiation does not significantly ablate the patterned metal layer during the exposing step.

50. The method of claim 48, wherein the ablation radiation does not significantly damage the patterned metal layer during the exposing step.

51. The method of claim 48, wherein the exposing step ablates substantially all of the regions of exposed dielectric layer.

52. The method of claim 48, wherein the patterned metal layer is a self-aligned ablation mask for ablation patterning at least a portion of the dielectric layer.

53. The method of claim 48, further comprising the step of depositing a second metal layer over the patterned metal layer and the ablated dielectric layer.

54. The method of claim 48, further comprising the step of patterning the sacrificial layer before providing the dielectric layer over the sacrificial layer.

55. The method of claim 48, further comprising the step of providing the sensor over a second sensor to form a capacitive comb sensor.

56. The method of claim 48, wherein, during the exposing step, the patterned metal layer act as an ablation mask for at least a portion of the dielectric layer, at least a portion of the sacrificial layer and at least a portion of the polymer substrate.

57. The method of claim 48, wherein the polymer substrate comprises a material selected from the group consisting of polymethylmethacrylate (PMMA), polyimide, polyethylene terephathalate (PET), polystyrene, polycarbonate, polyvinyl alcohol (PVA), polybenzimidazole, tetrafluoroethylene, SU-8, parylene, polyester, poly-dimethyl-siloxane (PDMS) and any combination of these.

58. The method of claim 48, wherein the polymer substrate has a thickness selected over the range of 10 μ

m to 1000 μ

m.

59. The method of claim 48, further comprising repeating one or more times the steps of:

providing an additional dielectric layer on at least a portion of the topmost layer;

depositing an additional metal layer on the additional dielectric layer; and

patterning the additional metal layer, thereby generating an additional patterned metal exposing regions of the additional dielectric layer;

wherein the exposing step includes exposing the exposed dielectric to ablation radiation to ablate at least a portion of the dielectric layer, and wherein the patterned metal layers function as in situ ablation masks and provide structural components of the electronic device.

60. The method of claim 48, wherein at least one metal layer is replaced by a layer comprising an inorganic dielectric.

61. The method of claim 60, wherein the inorganic dielectric is selected from the group consisting of silicon dioxide, silicon nitride and aluminum oxide.

62. The method of claim 48, wherein at least one metal layer is replaced by a layer comprising a semiconductor.

63. The method of claim 62, wherein the semiconductor is selected from the group consisting of Silicon, Germanium, Gallium Arsenide and Indium Phosphide.

64. A method of making a capacitive actuator, the method comprising the steps of:

providing a polymer substrate;

depositing a first metal layer on the polymer substrate;

patterning the first metal layer, thereby generating a first patterned metal layer that exposes one or more regions of exposed polymer substrate; and

providing a sacrificial layer on at least a portion of the first patterned metal layer;

providing a dielectric layer on at least a portion of the sacrificial layer, the first patterned metal layer and the polymer substrate;

depositing a second metal layer on the dielectric layer;

patterning the second metal layer, thereby generating a second patterned metal layer that exposes one or more regions of exposed dielectric layer;

exposing the second patterned metal layer and the regions of exposed dielectric layer to ablation radiation to ablate at least a portion of the dielectric layer, wherein the first patterned metal layer and the second patterned metal layer function as in situ ablation masks and provide structural components of the capacitive sensor; and

dissolving the sacrificial layer.

65. The method of claim 64, wherein the ablation radiation does not significantly ablate the first patterned metal layer or the second patterned metal layer during the exposing step.

66. The method of claim 64, wherein the ablation radiation does not significantly damage the first patterned metal layer or the second patterned metal layer during the exposing step.

67. The method of claim 64, wherein the exposing step ablates substantially all of the regions of exposed polymer substrate and substantially all the exposed regions of the dielectric layer.

68. The method of claim 64, wherein the first patterned metal layer and the second patterned metal layer are self-aligned ablation masks.

69. The method of claim 64, wherein the sacrificial layer has a thickness selected over the range of 100 nm to 50 μ

m.

70. The method of claim 64, wherein the sacrificial layer comprises a material selected from the group consisting of photoresist, polymer, metal oxide and dielectric.

71. The method of claim 64, wherein the sacrificial layer comprises a material which can be removed without damaging the polymer substrate, the patterned metal layers, or the dielectric layers.

72. The method of claim 64, wherein the sacrificial layer is removed by dissolution.

73. The method of claim 64, wherein the sacrificial layer is removed by exposure to a fluid selected from the group consisting of:

a solvent, an acid solution and an alkaline solution.

74. The method of claim 64, wherein the first metal layer has a thickness selected over the range of 100 nm to 5 μ

m, the second metal layer has a thickness selected over the range of 100 nm to 5 μ

m; and

the dielectric layer has a thickness selected over the range of 100 nm to 50 μ

m.

75. The method of claim 64, wherein the polymer substrate comprises a material selected from the group consisting of polymethylmethacrylate (PMMA), polyimide, polyethylene terephathalate (PET), polystyrene, polycarbonate, polyvinyl alcohol (PVA), polybenzimidazole, tetrafluoroethylene, SU-8, parylene, polyester, poly-dimethyl-siloxane (PDMS) and any combination of these.

76. The method of claim 64, wherein the polymer substrate has a thickness selected over the range of 10 μ

m to 1000 μ

m.

77. The method of claim 64, further comprising repeating one or more times the steps of:

providing an additional dielectric layer on at least a portion of the topmost layer;

depositing an additional metal layer on the additional dielectric layer; and

patterning the additional metal layer, thereby generating an additional patterned metal exposing regions of the additional dielectric layer;

wherein the exposing step includes exposing the exposed dielectric to ablation radiation to ablate at least a portion of the dielectric layer, and wherein the patterned metal layers function as in situ ablation masks and provide structural components of the electronic device.

78. The method of claim 64, wherein at least one metal layer is replaced by a layer comprising an inorganic dielectric.

79. The method of claim 78, wherein the inorganic dielectric is selected from the group consisting of silicon dioxide, silicon nitride and aluminum oxide.

80. The method of claim 64, wherein at least one metal layer is replaced by a layer comprising a semiconductor.

81. The method of claim 80, wherein the semiconductor is selected from the group consisting of Silicon, Germanium, Gallium Arsenide and Indium Phosphide.