Low k dielectric

• US 20090017272A1
• Filed: 06/13/2008
• Published: 01/15/2009
• Est. Priority Date: 06/15/2007
• Status: Active Grant

• Current Assignee: SBA Materials, Inc.
• Original Assignee: SBA Materials, Inc.
• Inventors: Phillips, Mark L. F., Thoms, Travis P.S.
• Granted Patent: US 8,932,702 B2
• Time in Patent Office: Days
• US Class Current: 428/195.100
• CPC Class Codes: H01L 21/02123 the material containing silicon
• CPC Class Codes: H01L 21/02203 the layer being porous
• CPC Class Codes: H01L 21/02282 liquid deposition, e.g. spin-coating, sol-gel techniques, spray coating
• CPC Class Codes: H01L 21/02348 treatment by exposure to UV light
• CPC Class Codes: H01L 21/3121 Layers comprising organo-silicon compounds
• CPC Class Codes: Y10T 428/24802 Discontinuous or differential coating, impregnation or bond [e.g., artwork, printing, retouched photograph, etc.]
• CPC Class Codes: Y10T 428/249953 Composite having voids in a component [e.g., porous, cellular, etc.]

Abstract

A spin-on dielectric of novel composition formed as a sol comprising an a source of silicon such as an orthosilicate ester, alone or in combination with an alkylated orthosilicate ester, a polar solvent, water, an acid catalyst, which may be a strong acid catalyst, and an amphiphilic block copolymer surfactant, optionally including an organic acid, a co-solvent and/or a reactive solvent. Also provided is a method of formulating the sol, a film made from the spin-on dielectric that has desirable electrical and mechanical properties, methods for treating the film described to optimize the film'"'"'s electrical and mechanical performance, and methods for depositing the film onto silicon, steel or other surfaces.

Claims

1. A fluid colloidal solution comprising:

a silica source;

a polar solvent;

water;

an acid catalyst; and

an amphiphilic block copolymer surfactant.

2. The fluid colloidal solution of claim 1 including an organic acid.

3. The fluid colloidal solution of claim 2 in which the organic acid is citric acid.

4. The fluid colloidal solution of claim 2 in which the organic acid is squaric acid.

5. The fluid colloidal solution of claim 1 including a reactive solvent.

6. The fluid colloidal solution of claim 5 in which the reactive solvent is propylene oxide.

7. The fluid colloidal solution of claim 1 in which the polar solvent is ethanol.

8. The fluid colloidal solution of claim 1 in which the polar solvent is acetonitrile.

9. The fluid colloidal solution of claim 1 in which the amphiphilic block copolymer is Pluronic P104.

10. The fluid colloidal solution of claim 1 in which the silica source is an orthosilicate ester alone or in combination with an alkylated orthosilicate ester.

11. The fluid colloidal solution of claim 10 in which the orthosilicate ester is TEOS.

12. The fluid colloidal solution of claim 10 in which the alkylated orthosilicate ester is selected from MTES or VTES.

13. The fluid colloidal solution of claim 1 in which the silicon source is a silicone.

14. The fluid colloidal solution of claim 13 in which the silicone is an ethoxy-terminated poly(dimethylsiloxane).

15. The fluid colloidal solution of claim 1 including an effective co-solvent.

16. The fluid colloidal solution of claim 15 in which the cosolvent is ethyl lactate.

17. The fluid colloidal solution of claim 15 in which the cosolvent is 2,2-ethoxy(ethoxyethanol).

18. The fluid colloidal solution of claim 15 in which the cosolvent is 2,2-ethoxy (ethoxyethanol) acetate.

19. The fluid colloidal solution of claim 15 in which the cosolvent is dipropylene glycol monomethyl ether.

20. The fluid colloidal solution of claim 1 in which the acid catalyst is a strong acid catalyst.

21. The fluid colloidal solution of claim 1 containing an adhesion promoter that improves adhesion of the cured film to a substrate.

22. The fluid colloidal solution of claim 21 in which the adhesion promoter is a silane coupling agent.

23. The fluid colloidal solution of claim 21 in which the substrate is copper, silicon, silicon nitride, or silicon carbide.

24. The fluid colloidal solution of claim 15 which has a shelf life at ambient storage temperature of at least 6 months.

25. A film formed from the colloidal solution of claim 15 by spin coating, dip coating, draw coating, spray coating, or inkjet printing onto a substrate.

26. The film of claim 25 where the substrate is a silicon wafer.

27. A film of claim 25 that has been soft baked at 130-150°

C.

28. A film of claim 27 that has been soft baked at 140°

C.

29. A film of claim 28 that can be stored for a period between 4 hours and indefinitely before annealing without degrading the final properties of the annealed film.

30. The film of claim 25 where the film is compatible with plasma processing.

31. The film of claim 25 where the film is insensitive to atmospheric moisture.

32. The film of claim 25 where the films is resistant to damage caused by ash.

33. A method of formulating a dielectric film, comprising

combining a silica source, polar solvent, water, acid catalyst, polymer surfactant, and cosolvent to form a single component colloidal solution.

34. The method of formulating a dielectric film of claim 33, wherein the solution has a shelf life of at least 6 months.

35. A method of formulating a dielectric film, comprising:

combining a silica source with a polar solvent to form a part A;

separately combining water, an acid catalyst, and a polymer surfactant with a polar solvent to form a part B; and

mixing part A and part B to form a fluid colloidal solution.

36. The method of claim 35 in which part A and part B are kept separate prior to mixing.

37. The method of claim 35, in which part A and part B have shelf lives of at least 6 months prior to mixing.

38. The method of claim 35 in which the silica source is thoroughly hydrolyzed prior to formulation with the other components.

39. The method of claim 35 in which residual water and solvent are removed by distillation and replaced with fresh solvent.

40. The method of claim 39 in which the fresh solvent is a different solvent.

41. The method of claim 39 in which the fresh solvent is a cosolvent.

42. A method for preparing a low dielectric film, comprising:

combining a silica source, polar solvent, water, acid catalyst, polymer surfactant, and cosolvent to form a single component colloidal solution, and

depositing the fluid colloidal solution onto a surface under conditions whereby to form a low dielectric film.

43. The method of claim 42 further comprising adding a cosolvent.

44. The method of claim 42, wherein the step of adding a cosolvent is completed at the time of manufacturing the film, or done later in part.

45. A dielectric film obtained by the method of claim 42.

46. A method for preparing a low dielectric film, comprising:

combining a silica source with a polar solvent to form a part A;

separately combining water, an acid catalyst, and a polymer surfactant with a polar solvent to form a part B;

mixing part A and part B to form a fluid colloidal solution; and

depositing the fluid colloidal solution onto a surface under conditions whereby to form a low dielectric film.

47. The method of claim 46 in which the fluid colloidal solution is heated to at least 40°

C. for at least one hour prior to depositing it onto the surface.

48. The method of claim 46 in which the fluid colloidal solution is deposited on the surface by spinning onto a silicon wafer.

49. The method of claim 48 where the film is annealed by an electron beam.

50. The method of claim 46 in which the film is soft baked at 130-150°

C.

51. The method of claim 50 in which the film is exposed to a reactive gas before or during bake.

52. The method of claim 51 in which the reactive gas is water vapor.

53. The method of claim 51 in which the reactive gas is ammonia vapor.

54. The method of claim 48 in which the film is exposed to UV illumination during soft bake.

55. The method of claim 48 in which the film is annealed at 200-450°

C.

56. The method of claim 55 in which the film is annealed at 250°

C. in the presence of a reducing atmosphere that contains hydrogen.

57. The method of claim 56 in which the film is exposed to UV illumination before being annealed.

58. The method of claim 56 in which the film is exposed to UV illumination during anneal.

59. The method of claim 58 in which the film is exposed to UV illumination at a wavelength or wavelengths between 170 nm and 365 nm during anneal.

60. The method of claim 55 in which the annealing is done in air.

61. The method of claim 55 in which the annealing is done in nitrogen or argon.

62. The method of claim 55 in which the annealing is done in helium.

63. The method of claim 55 in which the annealing is done in a reducing atmosphere that contains hydrogen.

64. The method of claim 55 in which the annealing is done in carbon dioxide.

65. The method of claim 55 in which the annealing is done in vacuum.

66. The method of claim 55 in which the annealing is done in nitrogen saturated with water vapor.

67. A dielectric film obtained by the method of claim 46.

68. The method of claim 66 in which adhesion of the film to the substrate is promoted by creating at least one monolayer of a native oxide on the substrate.

69. The method of claim 68 in which the method is O₂ plasma ashing, reactive ion etch with O₂, UV ozone treatment, applying a layer of SiO₂, or cleaning in an oxidizing chemical solution.

70. The method of claim 69 in which the oxidizing chemical solution is sulfuric acid or and/or hydrogen peroxide.

72. The nanoporous organic-containing oxide material of claim 47, wherein the metalloid is silicon.

73. The nanoporous organic-containing oxide of claim 47, wherein the material is spun into a film less than 2 μ

m thick upon anneal, and the material has a relationship between Young'"'"'s modulus (E) and dielectric constant (k) bounded by the points E=2.5 GPa, k=1.29 and E=8 GPa, k=2.6.

71. A nanoporous organic-containing oxide with a glassy wall structure and generally open pores, comprising:

a metal or metalloid oxide in which the metal or metalloid oxide is partially replaced with an alkyl or aryl group, and

a amphiphilic block copolymer template that can be removed by the action of heat.