Methods of making electromechanical three-trace junction devices

• US 6,784,028 B2
• Filed: 12/28/2001
• Issued: 08/31/2004
• Est. Priority Date: 12/28/2001
• Status: Expired due to Term

• Current Assignee: Nantero Incorporated
• Original Assignee: Nantero Incorporated
• Inventors: Brock, Darren K., Segal, Brent M., Rueckes, Thomas
• Primary Examiner(s): Ho, Hoai
• Assistant Examiner(s): HOANG, QUOC DINH
• Application Number:
  US10/033,032
• Publication Number:
  US 20030124837A1
• Time in Patent Office: 977 Days
• Field of Search: 438/105, 438/6, 438/128
• US Class Current: 438/128
• CPC Class Codes: B81C 1/00142 Bridges deformable micromirrors G02B26/0841
• CPC Class Codes: B81C 2201/019 Bonding or gluing multiple substrate layers
• CPC Class Codes: B82Y 10/00 Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
• CPC Class Codes: G11C 13/025 using fullerenes, e.g. C60, or nanotubes, e.g. carbon or silicon nanotubes
• CPC Class Codes: G11C 2213/16 Memory cell being a nanotube, e.g. suspended nanotube
• CPC Class Codes: G11C 2213/81 Array wherein the array conductors, e.g. word lines, bit lines, are made of nanowires
• CPC Class Codes: G11C 23/00 Digital stores characterised by movement of mechanical parts to effect storage, e.g. using balls; Storage elements therefor
• CPC Class Codes: H01H 1/0094 Switches making use of nanoelectromechanical systems [NEMS]
• CPC Class Codes: H01L 21/76838 characterised by the formation and the after-treatment of the conductors etching for patterning the conductors H01L21/3213
• CPC Class Codes: Y10S 977/734 Fullerenes, i.e. graphene-based structures, such as nanohorns, nanococoons, nanoscrolls or fullerene-like structures, e.g. WS2 or MoS2 chalcogenide nanotubes, planar C3N4, etc.

Abstract

Methods of producing an electromechanical circuit element are described. A lower structure having lower support structures and a lower electrically conductive element is provided. A nanotube ribbon (or other electromechanically responsive element) is formed on an upper surface of the lower structure so as to contact the lower support structures. An upper structure is provided over the nanotube ribbon. The upper structure includes upper support structures and an upper electrically conductive element. In some arrangements, the upper and lower electrically conductive elements are in vertical alignment, but in some arrangements they are not.

Claims

1. A method of producing an electromechanical circuit element, comprising:

providing a lower structure having lower support structures and a lower electrically conductive element;

forming a nanotube ribbon on an upper surface of the lower structure so as to contact the lower support structures;

forming an upper structure over the nanotube ribbon, the upper structure including upper support structures and an upper electrically conductive element.

2. The method of claim 1 wherein the lower electrically conductive element has a longitudinal axis and wherein the nanotube ribbon is formed to have an orientation that crosses the longitudinal axis of the lower electrically conductive element.

3. The method of claim 2, wherein the upper electrically conductive element has a longitudinal axis that is formed to be parallel to the longitudinal axis of the lower electrically conductive element.

4. The method of claim 2 wherein the nanotube ribbon is formed to cross the longitudinal axis of the lower electrically conductive element at about 90 degrees.

5. The method of claim 1, wherein the lower electrically conductive element is made of doped silicon.

6. The method of claim 1, wherein the upper electrically conductive element is made of doped silicon.

7. The method of claim 1, wherein the nanotube ribbon is made from selectively removing material from a non-woven fabric of nanotubes.

8. The method of claim 7, wherein the nanotube ribbon is substantially a monolayer of nanotubes.

9. The method of claim 7 wherein material is selectively removed from the non-woven fabric to create a ribbon having a predefined pattern.

10. The method of claim 9 wherein material is selectively removed using a lithographic process.

11. The method of claim 7 wherein the nanotube ribbon has at least one nanotube.

12. The method of claim 1 wherein the upper electrically conductive element is formed to be in vertical alignment with the lower electrically conductive element.

13. The method of claim 1 wherein the upper electrically conductive element is formed to be horizontally offset relative to the lower electrically conductive element.

14. The method of claim 1 wherein the lower electrically conductive element is formed to be disposed between lower support structures and wherein the upper electrically conductive elements is formed so that a portion thereof is over the upper support structure and another portion thereof is over the lower electrically conductive element.

15. A method of producing an electromechanical circuit element, comprising:

providing a lower structure having lower support structures and a lower electrically conductive element;

forming a nanotube ribbon on an upper surface of the lower structure so as to contact the lower support structures;

forming an upper structure over the nanotube ribbon, the upper structure including upper support structures and an upper electrically conductive element;

wherein lower structure is provided with a sacrificial layer of material, and

wherein the nanotube ribbon is formed over the sacrificial layer, and wherein the upper structure is provided with a sacrificial layer of material and wherein the method further includes removing the sacrificial layers of the upper and lower structures to suspend the nanotube ribbon between the upper and lower support structures.

16. The method of claim 15, wherein the sacrificial layer of the lower structure and the sacrificial layer of the upper structure are about the same thickness.

17. The method of claim 15, wherein sacrificial layers are removed by using wet chemical etchants.

18. The method of claim 17, wherein etching is achieved using etchants that diffuse through the nanotube layer.

19. The method of claim 15, wherein sacrificial layers are removed by using dry chemical etchants.

20. A method of producing an electromechanical circuit element, comprising:

providing a lower structure having lower support structures and a lower electrically conductive element;

forming a nanotube ribbon on an upper surface of the lower structure so as to contact the lower support structures;

forming an upper structure over the nanotube ribbon, the upper structure including upper support structures and an upper electrically conductive element;

wherein the nanotube ribbon is made from selectively removing material from a non-woven fabric of nanotubes;

wherein the non-woven fabric of nanotubes is patterned and then etched to selectively remove material from the non-woven fabric and to define nanotube ribbons.

21. A method of producing an electromechanical circuit element, comprising:

providing a lower structure having lower support structures and a lower electrically conductive element;

forming a nanotube ribbon on an upper surface of the lower structure so as to contact the lower support structures;

forming an upper structure over the nanotube ribbon, the upper structure including upper support structures and an upper electrically conductive element;

wherein a non-woven fabric is grown on the upper surface of the lower structure and portions are removed therefrom to form the nanotube ribbon.

22. The method of claim 21, wherein the upper surface of the lower structure is treated with a catalyst to facilitate growth of the non-woven fabric.

23. A method of producing an electromechanical circuit element, comprising:

providing a lower structure having lower support structures and a lower electrically conductive element;

forming a nanotube ribbon on an upper surface of the lower structure so as to contact the lower support structures;

forming an upper structure over the nanotube ribbon, the upper structure including upper support structures and an upper electrically conductive element;

wherein the upper structure is formed by

adding a sacrificial layer over the nanotube ribbon;

adding doped silicon over the sacrificial layer;

etching the doped silicon and sacrificial layer to form the upper electrically conductive elements with a sacrificial layer adjacent thereto;

providing insulating material over and around the etched, doped silicon and sacrificial layer;

backetching the insulating material to form the upper support structures;

providing a gate dielectric layer over the upper support structures; and

providing an electrical ground layer over the gate dielectric layer.

24. The method of claim 23 wherein doped silicon is etched to form upper electrically conductive element in vertical alignment with the lower electrically conductive elements.

25. The method of claim 23 wherein the insulating material is backetched to be about the same height as the upper electrically conductive element and the sacrificial layer thereunder.

26. A method of producing an electromechanical circuit element, comprising:

providing a lower structure having lower support structures and a lower electrically conductive element;

forming a nanotube ribbon on an upper surface of the lower structure so as to contact the lower support structures;

forming an upper structure over the nanotube ribbon, the upper structure including upper support structures and an upper electrically conductive element;

wherein the upper structure is formed by

selectively adding a sacrificial layer over the nanotube ribbon;

adding insulating material over and around the selectively added sacrificial layer;

processing the insulating material to define the upper support structures;

adding doped silicon between adjacent upper support structures to form the upper electrically conductive element;

providing a gate dielectric layer over the upper support structures; and

providing an electrical ground layer over the gate dielectric layer.

27. The method of claim 26 wherein the sacrificial layer is selectively added in alignment with the lower electrically conductive element.

28. A method of producing an electromechanical circuit element, comprising:

providing a lower structure having lower support structures and a lower electrically conductive element;

forming a nanotube ribbon on an upper surface of the lower structure so as to contact the lower support structures;

forming an upper structure over the nanotube ribbon, the upper structure including upper support structures and an upper electrically conductive element;

wherein the upper support structure is formed by

selectively adding a sacrificial layer over the nanotube ribbon;

adding doped silicon over and around the selectively added sacrificial layer;

processing the doped silicon to define the upper electrically conductive element and to define cavities adjacent thereto;

providing insulating material to the cavities to form the upper support structures;

providing a gate dielectric layer over the upper support structures; and

providing an electrical ground layer over the gate dielectric layer.

29. The method of claim 28 wherein the sacrificial layer is selectively added to be in alignment with the lower electrically conductive element.

30. A method of producing an electromechanical circuit element, comprising:

providing a lower structure having lower support structures and a lower electrically conductive element;

forming a nanotube ribbon on an upper surface of the lower structure so as to contact the lower support structures;

forming an upper structure over the nanotube ribbon, the upper structure including upper support structures and an upper electrically conductive element;

wherein the upper structure is formed by

providing upper support structures in alignment with the lower support structures;

providing sacrificial material in alignment with the lower electrically conductive element;

providing the upper electrically conductive element over a portion of an upper support structure and over a portion of the sacrificial material.

31. The method of claim 30 wherein the upper electrically conductive element is provided so that it is horizontally shifted relative to the lower electrically conductive element by about one half the width of the lower electrically conductive element.

32. The method of claim 30 wherein the upper support structures are provided by

forming a layer of support material over the nanotube ribbons;

patterning and selectively removing support material from the layer to define the upper support structures and to define cavities therebetween.

33. The method of claim 32 wherein the sacrificial material is provided by defining the cavities to be in alignment with the lower electrically conductive element and by filling the cavities with sacrificial material.

35. The method of claim 30 wherein sacrificial material is provided by

forming a layer of sacrificial material over the nanotube ribbons;

selectively removing sacrificial material so that the remaining material is in alignment with the lower electrically conductive element and to define cavities on either side of the remaining sacrificial material.

36. The method of claim 35 wherein the upper support structures are provided by filling the cavities with insulating material.

37. The method of claim 36 wherein the upper electrically conductive element is provided by

depositing doped silicon over the sacrificial material and over the upper support structures;

selectively removing portions of the doped silicon to define the upper electrically conductive element.

38. The method of claim 30 wherein the upper support structure is formed by

selectively growing insulating material in vertical alignment with the lower support structures to define upper support structures and to define cavities therebetween.

39. The method of claim 38 wherein insulating material is selectively grown using a selective CVD process.

40. The method of claim 30 wherein sacrificial material is provided by selectively depositing sacrificial material in vertical alignment with the lower electrically conductive element.

34. The method of 33 wherein the upper electrically conductive element is provided by

depositing doped silicon over the sacrificial material and over the upper support structures;

selectively removing portions of the doped silicon to define the upper electrically conductive element.

41. A method of producing an electromechanical circuit element, comprising:

providing a lower structure having lower support structures and a lower electrically conductive element;

forming a nanotube ribbon on an upper surface of the lower structure so as to contact the lower support structures;

forming an upper structure over the nanotube ribbon, the upper structure including upper support structures and an upper electrically conductive element;

wherein the upper structure is formed by

depositing a layer of sacrificial material over the nanotube ribbon and lower structure;

depositing a layer of doped silicon over the layer of sacrificial material;

patterning and selectively removing portions of the doped silicon to form the upper electrically conductive element;

removing a portion of the sacrificial material that is in vertical alignment with the lower electrically conductive element.

42. The method of claim 41 wherein the portion of sacrificial material is removed by first using a RIE process to remove sacrificial material not covered by the upper electrically conductive element and then by subjecting remaining sacrificial material to a subsequent etching process.

43. A method of producing an electromechanical circuit element, comprising:

providing a lower structure having lower support structures and a lower electrically conductive element;

forming a nanotube ribbon on an upper surface of the lower structure so as to contact the lower support structures;

forming an upper structure over the nanotube ribbon, the upper structure including upper support structures and an upper electrically conductive element;

wherein the lower structure includes a first type of sacrificial material and

wherein the upper support structure is formed by

providing a layer of a second type of sacrificial material over the nanotube ribbon and the lower support structure;

providing a layer of doped silicon over the layer of the second type of sacrificial material;

selectively removing a portion of the doped silicon to define the upper electrically conductive element and to expose a portion of the layer of the second type of sacrificial material;

removing the exposed portion of the layer of the second type of sacrificial material;

removing the first type of sacrificial material in the lower structure;

removing a remaining portion of the layer of the second type of sacrificial material that is in vertical alignment with the lower electrically conductive element.

44. The method of claim 43 wherein the first type and the second type of sacrificial material have different etching characteristics.

45. A method of producing an electromechanical circuit element, comprising:

providing a lower structure having lower support structures and a lower electrically conductive element;

forming a nanotube ribbon on an upper surface of the lower structure so as to contact the lower support structures;

forming an upper structure over the nanotube ribbon, the upper structure including upper support structures and an upper electrically conductive element.

46. A method of producing an electromechanical circuit element, comprising:

providing a lower structure;

forming a nanotube ribbon on an upper surface of the lower structure;

forming an upper structure over the nanotube ribbon;

wherein at least one of the lower and upper structures includes a region having sacrificial material in contact with the nanotube ribbon and wherein the method includes the removal of such sacrificial material.

47. The method of claim 46 wherein the lower and upper structures are formed to have recesses in at least one of their surfaces and wherein the nanotube ribbon is made to suspend between the recesses of the lower and upper structures.

48. The method of claim 47 wherein the lower and upper structures are formed to each have conductive traces in cross relation relative to the suspended nanotube ribbon.

49. The method of claim 46 wherein the nanotube ribbon is anchored to at least one of the upper and lower structures.

50. The method of claim 46 wherein the upper structure pins the nanotube ribbon to the lower structure.