Methods for fabricating refined graphite-based structures and devices made therefrom

• US 9,478,422 B2
• Filed: 02/25/2014
• Issued: 10/25/2016
• Est. Priority Date: 02/25/2013
• Status: Expired due to Fees

• Current Assignee: Solan, LLC
• Original Assignee: Solan, LLC
• Inventors: Davis, Mark Alan
• Primary Examiner(s): DUCLAIR, STEPHANIE P.
• Application Number:
  US14/396,039
• Publication Number:
  US 20150371854A1
• Time in Patent Office: 973 Days
• Field of Search: None
• US Class Current: 1/1
• CPC Class Codes: B82B 1/00 Nanostructures formed by manipulation of individual atoms or molecules, or limited collections of atoms or molecules as discrete units
• CPC Class Codes: B82B 1/005 Constitution or structural means for improving the physical properties of a device
• 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 40/00 Manufacture or treatment of nanostructures
• CPC Class Codes: C01B 2204/04 Specific amount of layers or specific thickness
• CPC Class Codes: C01B 32/184 Preparation
• CPC Class Codes: C01B 32/205 Preparation
• CPC Class Codes: C23C 16/26 Deposition of carbon only
• CPC Class Codes: C23C 16/56 After-treatment
• CPC Class Codes: H01B 13/0026 Apparatus for manufacturing conducting or semi-conducting layers, e.g. deposition of metal
• CPC Class Codes: H01L 21/0226 formation by a deposition process per se C23C
• CPC Class Codes: H01L 21/02263 deposition from the gas or vapour phase
• CPC Class Codes: H01L 21/02373 Group 14 semiconducting materials
• CPC Class Codes: H01L 21/02422 Non-crystalline insulating materials, e.g. glass, polymers
• CPC Class Codes: H01L 21/02527 Carbon, e.g. diamond-like carbon
• CPC Class Codes: H01L 21/0262 Reduction or decomposition of gaseous compounds, e.g. CVD
• CPC Class Codes: H01L 21/02639 Preparation of substrate for selective deposition
• CPC Class Codes: H01L 21/02645 Seed materials
• CPC Class Codes: H01L 21/042 Changing their shape, e.g. forming recesses etching of the semiconductor body H01L21/302
• CPC Class Codes: H01L 21/30604 Chemical etching
• CPC Class Codes: H01L 29/0684 : characterised by the shape, relative sizes or dispositions of the semiconductor regions or junctions between the regions
• CPC Class Codes: H01L 29/1606 : Graphene
• CPC Class Codes: Y10T 428/24851 : Intermediate layer is discontinuous or differential

Abstract

Graphite-based devices with a reduced characteristic dimension and methods for forming such devices are provided. One or more thin films are deposited onto a substrate and undesired portions of the deposited thin film or thin films are removed to produce processed elements with reduced characteristic dimensions. Graphene layers are generated on selected processed elements or exposed portions of the substrate after removal of the processed elements. Multiple sets of graphene layers can be generated, each with a different physical characteristic, thereby producing a graphite-based device with multiple functionalities in the same device.

Claims

1. A method of forming a graphite-based structure on a patterned substrate, the patterned substrate comprising a plurality of initial elements and a plurality of initial trenches, wherein each respective initial element in the plurality of initial elements is separated from an adjacent initial element in the plurality of initial elements by a corresponding initial trench in the plurality of initial trenches, the method comprising:

(A) conformally depositing a first material on the patterned substrate, thereby producing a first thin film overlaying the patterned substrate, wherein the first thin film is characterized by a first thickness that does not exceed (a) a minimum initial element width of the plurality of initial elements, or (b) a minimum initial trench width of the plurality of initial trenches;

(B) anisotropically etching the substrate to remove other portions of the first thin film while retaining portions of the first thin film overlaid on side walls of the plurality of initial elements, thereby producing a plurality of processed elements, wherein

(i) each respective processed element in the plurality of processed elements is characterized by a retained portion of the first thin film on a side wall of a corresponding initial element in the plurality of initial elements, and

(ii) the plurality of processed elements has a reduced width that corresponds to the first thickness and does not exceed (a) the minimum initial element width or (b) the minimum initial trench width; and

(C) concurrently generating a first plurality of graphene layers, wherein each respective graphene layer in the first plurality of graphene layers is generated on a top surface of a corresponding processed element in the plurality of processed elements, thereby producing said refined graphite-based structure with isolated graphene layers having the reduced width.

2. The method of claim 1, further comprising:

(D) removing the plurality of initial elements by selectively etching the patterned substrate, thereby producing a refined pattern on the patterned substrate that comprises the plurality of processed elements and a plurality of processed trenches, wherein

(i) a trench in the plurality of processed trenches is a void space produced by (a) the removal of an initial element in the plurality of initial elements or (b) the anisotropically etching of the substrate to remove other portions of the first thin film, and

(ii) each respective processed element in the plurality of processed elements is separated from an adjacent processed element in the plurality of processed elements by a corresponding processed trench in the plurality of processed trenches; and

(E) repeating steps (A) and (B) on the patterned substrate having the refined pattern,

wherein both steps (D) and (E) are conducted prior to the concurrently generating the first plurality of graphene layers (C).

3. The method of claim 2, wherein the repeating steps (A) and (B) on the patterned substrate produces a plurality of pitches, wherein each pitch in the plurality of pitches does not exceed an initial pitch of the initial patterned substrate, wherein each pitch in the plurality of pitches is defined by a distance between the centers of neighboring processed elements in the plurality of processed elements.

4. The method of claim 3, wherein a first pitch and a second pitch in the plurality of pitches differ from each other.

5. The method of claim 3, wherein at least a first pitch, a second pitch, and a third pitch in the plurality of pitches differ from each other.

6. The method of claim 1, wherein the plurality of processed elements is defined by retained portions of the first thin film on first and second side walls of each initial element in the plurality of initial elements, wherein

(i) retained portions of the first thin film on the first and second side walls of a first initial element in the plurality of initial elements defines first and second processed elements in the plurality of processed elements, respectively, and

(ii) retained portions of the first thin film on the first and second side walls of a second initial element in the plurality of initial elements defines third and fourth processed elements in the plurality of processed elements.

7. The method of claim 1, wherein the first thin film comprises a foundation material.

8. The method of claim 7, wherein the foundation material comprises a catalytic metal or a non-metal material.

9. The method of claim 7, wherein the foundation material is Si, SiC, doped Si, or doped SiC.

10. The method of claim 1, wherein the concurrently generating the first plurality of graphene layers (C) comprises an epitaxial growth, a chemical vapor deposition (CVD) growth, or a combination thereof.

11. The method of claim 10, wherein the atomic layer deposition is repeated in order to collectively deposit the first material at the first thickness.

12. The method of claim 1, wherein the conformally depositing (A) is performed using atomic layer deposition.

13. The method of claim 1, wherein the reduced width is between 2 nm and 100 nm.

14. The method of claim 1, wherein a graphene layer in the first plurality of graphene layers consists of between 1 and 500 graphene sheets.

15. The method of claim 1, wherein a processed element in the plurality of processed elements has a substantially same height as a corresponding initial element in the plurality of initial elements.

16. The method of claim 1, wherein a processed element in the plurality of processed elements has a different height than a corresponding initial element in the plurality of initial elements.

17. The method of claim 1, wherein a processed element in the plurality of processed elements is taller than a corresponding initial element in the plurality of initial elements by between 2 nm and 300 nm.

18. The method of claim 1, wherein a processed element in the plurality of processed elements is taller than a corresponding initial element in the plurality of initial elements by between 2 nm and 100 nm.

19. The method of claim 1, wherein a processed element in the plurality of processed elements is taller than a corresponding initial element in the plurality of initial elements by between 100 nm and 300 nm.

20. The method of claim 1, wherein a processed element in the plurality of processed elements has a height that is between 25 nm and 1000 nm.

21. The method of claim 1, wherein a processed element in the plurality of processed elements has a height that is between 1 μ

m and 5 μ

m.

22. The method of claim 1, wherein a processed element in the plurality of processed elements has a height that is between 5 μ

m and 10 μ

m.

23. The method of claim 1, wherein the plurality of initial elements comprises a foundation material, the method further comprising:

generating a second plurality of graphene layers on the plurality of initial elements, concurrently or sequentially with the generating the first plurality of graphene layers on the plurality of processed elements, thereby producing said graphite-based structure with isolated graphene layers having initial element widths and the reduced width.

24. A method of forming a graphite-based structure on a patterned substrate, the patterned substrate comprising a plurality of initial elements and a plurality of initial trenches, wherein each respective initial element in the plurality of initial elements is separated from an adjacent initial element in the plurality of initial elements by a corresponding initial trench in the plurality of initial trenches, the method comprising:

(A) conformally depositing a first material on the patterned substrate, thereby producing a first thin film overlaying the patterned substrate, wherein the first thin film is characterized by a first thickness that does not exceed (a) a minimum initial element width or (b) a minimum initial trench width;

(B) anisotropically etching the substrate to remove other portions of the first thin film while retaining portions of the first thin film overlaid on side walls of the plurality of initial elements, thereby producing a plurality of processed elements and exposing a portion of each initial trench in the plurality of initial trenches to the substrate, wherein

(i) each respective processed element in the plurality of processed elements is defined by a retained portion of the first thin film on a side wall of a corresponding initial element in the plurality of initial elements, and

(ii) each processed element in the plurality of processed elements has a reduced width that corresponds to the first thickness and does not exceed (a) the minimum initial element width or (b) the minimum initial trench width;

(C) backfilling, subsequent to the anisotropically etching of the substrate (B), the exposed portion of each initial trench in the plurality of initial trenches;

(D) removing the plurality of processed elements by selectively etching the substrate, thereby exposing portions of the substrate that were underneath the plurality of processed elements, wherein each of the exposed portions of the substrate that was underneath a corresponding processed element in the plurality of processed elements is characterized by the reduced width; and

(F) concurrently generating a plurality of graphene layers, wherein each respective graphene layer in the plurality of graphene layers is generated on a corresponding exposed portion of the substrate that was underneath a processed element in the plurality of processed elements, thereby producing said graphite-based structure with isolated graphene layers having the reduced width.

25. The method of claim 24, further comprising conducting a planarization process subsequent to the backfilling that planarizes a backfill in the plurality of trenches, relative to the plurality of processed elements.

26. The method of claim 24, wherein the exposed portion of the substrate that was underneath a processed element comprises a foundation material.

27. The method of claim 24, the method further comprising depositing a foundation material on the exposed portions of the substrate after the anisotropically etching (B) and before the generating the plurality of graphene layers (F).

28. The method of claim 24, further comprising:

(G) removing the plurality of initial elements by selectively etching the substrate, thereby producing a refined pattern on the patterned substrate that comprises the plurality of processed elements and a plurality of processed trenches, wherein

(i) a trench in the plurality of processed trenches is a void space produced by step (G) or step (B), and

(ii) each respective processed element in the plurality of processed elements is separated from an adjacent processed element in the plurality of processed elements by a corresponding processed trench in the plurality of processed trenches; and

(H) repeating steps (A) and (B) on the patterned substrate having the refined pattern,

wherein both steps (G) and (H) are conducted prior to the backfilling.

29. A method of forming a graphite-based structure on a patterned substrate, the patterned substrate comprising a plurality of initial elements and a plurality of initial trenches, wherein each respective initial element in the plurality of initial elements is separated from an adjacent initial element in the plurality of initial elements by a corresponding initial trench in the plurality of initial trenches, the method comprising:

(A) conformally depositing a plurality of thin films on the patterned substrate, wherein the depositing is conducted sequentially thereby sequentially depositing respective thin films of the plurality of thin films, wherein

(i) each thin film in the plurality of thin films has a thickness that does not exceed a minimum initial element width of the plurality of initial elements,

(ii) a sum of the thicknesses of each thin film in the plurality of thin films does not exceed a minimum initial trench width of the plurality of initial trenches, and

(iii) each thin film in the plurality of thin films comprises a material that is different than an adjacent thin film in the plurality of thin films;

(B) anisotropically etching the substrate to remove portions of the plurality of thin films overlaid on the tops of initial elements in the plurality of initial elements while retaining portions of the plurality of thin films overlaid on side walls of the plurality of initial elements, thereby producing a plurality of processed element sets, wherein

(i) each respective set in the plurality of processed element sets comprises a plurality of processed elements that are defined by retaining portions of a corresponding thin film in the plurality of thin films, and

(ii) the plurality of processed elements in each respective processed element set has a respective reduced width that corresponds to the thickness of a corresponding thin film and does not exceed (a) the minimum initial element width or (b) the minimum initial trench width; and

(C) generating one or more pluralities of graphene layers on one or more selected processed element sets in the plurality of processed element sets, wherein each respective graphene layer in the one or more pluralities of graphene layers is generated on a top surface of a corresponding processed element in the one or more selected processed element sets, thereby producing said refined graphite-based structure with isolated graphene layers having one or more reduced widths.

30. The method of claim 29, wherein a processed element in one processed element set has a top surface at an elevation different than an elevation of a corresponding top surface of a processed element in another processed element set in the plurality of processed element sets.

31. The method of claim 29, wherein a processed element in one processed element set in the plurality of processed element sets has a top surface at a same elevation as a top surface of a processed element in another processed element set in the plurality of processed element sets.

32. The method of claim 29, wherein the conformally depositing comprises successively depositing a first thin film comprising a foundation material and a second thin film comprising a non-foundation material.

33. The method of claim 32, wherein the non-foundation material is glass, silicon dioxide, neoceram, or sapphire.

34. The method of claim 32, wherein the foundation material is Pt, Au, Fe, Rh, Ti, Ir, Ru, Ni, or Cu.

35. The method of claim 29, wherein the plurality of the initial elements comprises a non-foundation material, wherein

(a) the plurality of thin films comprises a first thin film, a second thin film and a third thin film, wherein

(i) the first thin film is overlaid on the patterned substrate, has a first thickness, and comprises a first foundation material,

(ii) the second thin film is overlaid on the first thin film, has a second thickness and comprises a non-foundation material, and

(iii) the third thin film is overlaid on the second thin film, has a third thickness and comprises a second foundation material;

(b) the plurality of processed element sets comprises a first processed element set, a second processed element set and a third processed element set, wherein

(i) the first processed element set comprises a plurality of processed elements that are defined by retaining portions of the first thin film in the plurality of thin films and have a first reduced width that corresponds to the first thickness,

(ii) the second processed element set comprises a plurality of processed elements that are defined by retaining portions of the second thin film in the plurality of thin films and have a second reduced width that corresponds to the second thickness,

(iii) the third processed element set comprises a plurality of processed elements that are defined by retaining portions of the third thin film in the plurality of thin films and have a third reduced width that corresponds to the third thickness, and

(iv) a respective processed element in the first processed element set is separated from an adjacent processed element in the third processed element set by a corresponding processed element in the second processed element set; and

(c) the generating (C) produces the one or more pluralities of graphene layers comprising first and second pluralities of graphene layers, thereby producing said refined graphite-based structure with isolated graphene layers having the first and third reduced width, wherein

(i) each respective graphene layer in the first plurality of graphene layers is generated on a top surface of a corresponding processed element in the first set, and

(ii) each respective graphene layer in the second plurality of graphene layers is generated on a top surface of a corresponding processed element in the third set.

36. The method of claim 35, wherein the first processed element set or the third processed element set has a substantially same height as the plurality of initial elements.

37. The method of claim 35, wherein the second processed element set or the fourth processed element set has a substantially same height as the plurality of initial elements.

38. The method of claim 35, wherein the first foundation material is the same as the second foundation material.

39. The method of claim 35, wherein the first foundation material is different than the second foundation material.

40. The method of claim 35, wherein the first foundation material comprises nickel (Ni), the non-foundation material comprises silicon dioxide (SiO₂) and the second foundation material comprises copper (Cu).

41. The method of claim 29, wherein the plurality of the initial elements comprises a foundation material, the method further comprising:

generating a plurality of graphene layers on the plurality of the initial elements, concurrently or sequentially with the generating the one or more pluralities of graphene layers on one or more selected sets in the plurality of processed element sets, thereby producing said refined graphite-based structure with at least one isolated graphene layer having an initial element width and one or more isolated graphene layers having reduced widths.

42. The method of claim 29, wherein

(a) the plurality of thin films comprises a first thin film, a second thin film, a third thin film and a fourth thin film, wherein

(i) the first thin film is overlaid on the patterned substrate, has a first thickness, and comprises a first non-foundation material,

(ii) the second thin film is overlaid on the first thin film, has a second thickness, and comprises a first foundation material,

(iii) the third thin film is overlaid on the second thin film, has a third thickness, and comprises a second non-foundation material, and

(iv) the fourth thin film is overlaid on the third thin film, has a fourth thickness and comprises a second foundation material;

(b) the plurality of processed element sets comprises a first processed element set, a second processed element set, a third processed element set and a fourth processed element set, wherein

(i) the first processed element set comprises a plurality of processed elements that are defined by retaining portions of the first thin film in the plurality of thin films and have a first reduced width that corresponds to the first thickness,

(ii) the second processed element set comprises a plurality of processed elements that are defined by retaining portions of the second thin film in the plurality of thin films and have a second reduced width that corresponds to the second thickness,

(iii) the third processed element set comprises a plurality of processed elements that are defined by retaining portions of the third thin film in the plurality of thin films and have a third reduced width that corresponds to the third thickness,

(iv) the fourth processed element set comprises a plurality of processed elements that are defined by retaining portions of the fourth thin film in the plurality of thin films and have a fourth reduced width that corresponds to the fourth thickness,

(v) a respective processed element in the first processed element set is separated from an adjacent processed element in the third processed element set by a corresponding processed element in the second processed element set, and

(vi) a respective processed element in the second processed element set is separated from an adjacent processed element in the fourth processed element set by a corresponding processed element in the third processed element set; and

(c) the generating (C) produces one or more pluralities of graphene layers comprising first and second pluralities of graphene layers, thereby producing said refined graphite-based structure with isolated graphene layers having the second or the fourth reduced width, wherein

(i) each respective graphene layer in the first plurality of graphene layers is generated on a top surface of a corresponding processed element in the second set, and

(ii) each respective graphene layer in the second plurality of graphene layers is generated on a top surface of a corresponding processed element in the fourth set.

43. The method of claim 42, wherein the first processed element set or the third processed element set has a different height than the plurality of initial elements.

44. The method of claim 42, wherein the second processed element set or the fourth processed element set has a different height than the plurality of initial elements.

45. The method of claim 42, wherein the first foundation material is the same as the second foundation material.

46. The method of claim 42, wherein the first foundation material is different than the second foundation material.

47. The method of claim 42, wherein the first and second non-foundation materials comprise silicon dioxide (SiO₂), the first foundation material comprises nickel (Ni), and the second foundation material comprises copper (Cu).

48. The method of claim 29, wherein each processed element set in the plurality of processed element sets has a reduced width that is between 2 nm and 100 nm.

49. The method of claim 29, wherein each processed element set in the plurality of processed element sets has a substantially same height as the plurality of initial elements.

50. The method of claim 29, wherein at least one processed element set in the plurality of processed element sets has a different height than the plurality of initial elements.