Silica zeolite low-k dielectric thin films

• US 20020134995A1
• Filed: 03/28/2002
• Published: 09/26/2002
• Est. Priority Date: 07/13/2000
• Status: Active Grant

• Current Assignee: Regents of the University of California (University of California)
• Original Assignee: Regents of the University of California (University of California)
• Inventors: Yan, Yushan, Wang, Huanting, Wang, Zhengbao
• Granted Patent: US 6,630,696 B2
• Time in Patent Office: Days
• US Class Current: 257/200
• CPC Class Codes: C01B 37/02 Crystalline silica-polymorphs, e.g. silicalites dealuminated aluminosilicate zeolites
• CPC Class Codes: H01L 21/02126 the material containing Si, O, and at least one of H, N, C, F, or other non-metal elements, e.g. SiOC, SiOC:H or SiONC
• CPC Class Codes: H01L 21/02203 the layer being porous
• CPC Class Codes: H01L 21/02216 the compound being a molecule comprising at least one silicon-oxygen bond and the compound having hydrogen or an organic group attached to the silicon or oxygen, e.g. a siloxane
• CPC Class Codes: H01L 21/02282 liquid deposition, e.g. spin-coating, sol-gel techniques, spray coating
• CPC Class Codes: H01L 21/02337 treatment by exposure to a gas or vapour
• CPC Class Codes: H01L 21/02345 treatment by exposure to radiation, e.g. visible light
• CPC Class Codes: H01L 21/02356 treatment to change the morphology of the insulating layer, e.g. transformation of an amorphous layer into a crystalline layer
• CPC Class Codes: H01L 21/31604 Deposition from a gas or vapour H01L21/31691, H01L21/31695 take precedence
• CPC Class Codes: H01L 21/31695 Deposition of porous oxides or porous glassy oxides or oxide based porous glass
• CPC Class Codes: H01L 21/76801 characterised by the formation and the after-treatment of the dielectrics, e.g. smoothing
• CPC Class Codes: H01L 21/7682 the dielectric comprising air gaps

Abstract

Thin films for use as dielectric in semiconductor and other devices are prepared from silica zeolites, preferably pure silica zeolites such as pure-silica MFI. The films have low k values, generally below about 2.7, ranging downwards to k values below 2.2. The films have relatively uniform pore distribution, good mechanical strength and adhesion, are relatively little affected by moisture, and are thermally stable. The films may be produced from a starting zeolite synthesis or precursor composition containing a silica source and an organic zeolite structure-directing agent such as a quaternary ammonium hydroxide. In one process the films are produced from the synthesis composition by in-situ crystallization on a substrate. In another process, the films are produced by spin-coating, either through production of a suspension of zeolite crystals followed by redispersion or by using an excess of the alkanol produced in preparing the synthesis composition. Zeolite films having patterned surfaces may also be produced.

Claims

17. A process for the production of a silica zeolite film on a semiconductor substrate, comprising:

(a) combining a silica source selected from organic silica sources and inorganic silica sources with an organic hydroxide zeolite-structure-directing agent (SDA) and water to produce a zeolite synthesis composition containing the structure-directing agent, the silica source and water in a molar ratio of x₁ SDA;

1 silica source;

y₁ H₂O, wherein the value of x₁ is from about 0.2 to about 0.5 and the value of y, is from about 5 to about 30;

(b) heating the composition of step (a) to produce an aqueous colloidal suspension of silica zeolite crystals;

(c) separating the crystals from the product of step (b)

(d) dispersing the separated crystals from step (c) in a dispersing agent to form a suspension of the crystals in the dispersing agent,

(e) depositing the crystal suspension of step (d) on a semiconductor substrate; and

(f) rotating the substrate from step (e) under conditions so as to produce a silica zeolite film thereon by spin-coating.

32. A process for the production of a silica zeolite film on a semiconductor substrate, comprising:

(a) combining a silica source selected from organic silica sources and inorganic silica sources with an organic hydroxide zeolite-structure-directing agent (SDA), water, and an alkanol selected from ethanol and methanol, to produce a zeolite synthesis composition containing the structure-directing agent, silica source, water and alkanol in a molar ratio of x₂ SDA;

1 silica source;

y₂ H₂O;

z₂ alkanol, wherein the value of x₂ is from about 0.2 to about 0.5, the value of y₂ is from about 10 to about 20, and the value of z₂ is from about 1 to about 30;

(b) heating the composition of step (a) to produce an aqueous colloidal suspension of silica zeolite crystals;

(c) depositing the crystal suspension of step (b) on a semiconductor substrate;

and

(d) rotating the substrate from step (c) under conditions so as to produce a silica zeolite film thereon by spin coating.

1. A semiconductor device comprising a semiconductor substrate, one or more metal layers or structures located on said substrate, and one or more dielectric films, wherein at least one dielectric film comprises a silica zeolite.

2. A process for production of a silica zeolite film on a semiconductor substrate, comprising:

(a) combining a silica source selected from organic silica sources and inorganic silica sources with an organic hydroxide zeolite-structure-directing agent (SDA) and water to produce a zeolite synthesis composition containing the structure-directing agent, the silica source and water, in a molar ratio of x SDA;

1 silica source;

y H₂O, wherein the value of x is from about 0.2 to about 0.6 and the value of y is from about 100 to about 200.

(b) contacting the substrate to be coated with the synthesis composition; and

(c) heating the substrate and synthesis composition from step (b) to produce a silica zeolite film on the substrate.

3. A process according to claim 2 in which the value of x is from about 0.2 to about 0.45 and the value of y is from about 140 to about 180.

4. A process according to claim 2 in which the value of x is 0.32 and the value of y is 165.

5. A process according to claim 2 in which the silica source is a C₁-C₂ alkyl orthosilicate.

6. A process according to claim 2 in which the silica source is selected from filmed silica, silica gel and colloidal silica.

7. A process according to claim 2 in which the structure-directing agent is a quaternary ammonium hydroxide.

8. A process according to claim 2 in which the silica source is ethyl orthosilicate and the structure-directing agent is tetrapropylammonium hydroxide.

9. A process according to claim 2 further comprising (d) heating the substrate and film of step (c) to a temperature of from about 350 to about 550°

C.

10. A process according to claim 2 further comprising treating the silica film of step (d) to remove surface hydroxyl groups therefrom.

11. A process according to claim 2 in which the silica zeolite is a high-silica MFI zeolite.

12. A process according to claim 2 in which the silica zeolite is a pure-silica MFI zeolite.

13. A process according to claim 2 in which the semiconductor substrate is a silicon wafer or a gallium arsenide wafer.

14. A process according to claim 2 in which the substrate comprises a silicon wafer or a gallium arsenide wafer and one or more metal layers or structures located on said wafer.

15. A semiconductor substrate having at least one silica zeolite film thereon produced by a process according to claim 2.

16. A semiconductor substrate according to claim 16 in which the at least one silica zeolite film is a pure-silica zeolite film.

18. A process according to claim 17 in which the value of x₁ is from about 0.3 to about 0.4 and the value of y₁ is from about 10 to about 20.

19. A process according to claim 17 in which the value of x₁ is 0.36 and the value of y₁ is 14.29.

20. A process according to claim 17 in which the silica source is a C₁-C₂ alkyl orthosilicate.

21. A process according to claim 17 in which the silica source is selected from fumed silica, silica gel and colloidal silica.

22. A process according to claim 17 in which the structure-directing agent is a quaternary ammonium hydroxide.

23. A process according to claim 17 in which the silica source is ethyl orthosilicate and the structure-directing agent is tetrapropylammonium hydroxide.

24. A process according to claim 17 further comprising (g) heating the film of step (f) to a temperature of from about 350 to about 550°

C.

25. A process according to claim 24 further comprising treating the silica film of step (g) to remove surface hydroxyl groups therefrom.

26. A process according to claim 17 in which the silica zeolite is a high-silica MFI zeolite.

27. A process according to claim 17 in which the silica zeolite is a pure-silica MFI zeolite.

28. A process according to claim 17 in which the semiconductor substrate is a silicon wafer or a gallium arsenide wafer.

29. A process according to claim 17 in which the substrate comprises a silicon wafer or a gallium arsenide wafer and one or more metal layers or structures located on said wafer.

30. A semiconductor substrate having at least one silica zeolite film thereon produced by a process according to claim 17.

31. A semiconductor according to claim 30 wherein the at least one silica zeolite film is a pure-silica MFI zeolite film.

33. A process according to claim 32 in which the value of x₂ is from about 0.3 to about 0.4, and the value of y₂ is from about 12 to about 18.

34. A process according to claim 32 in which the value of x₂ is 0.36, the value of y₂ is 14.29, and the value of z₂ is 11.2.

35. A process according to claim 32 in which the silica source is a C₁-C₂ alkyl orthosilicate.

36. A process according to claim 32 in which the silica source is selected from filmed silica, silica gel and colloidal silica.

37. A process according to claim 32 in which the structure-directing agent is a quaternary ammonium hydroxide.

38. A process according to claim 32 in which the silica source is ethyl orthosilicate, the template is tetrapropylammonium hydroxide, and the alkanol is ethanol.

39. A process according to claim 32 further comprising (e) heating the film of step (d) to a temperature of from about 350 to about 550°

C.

40. A process according to claim 39 further comprising treating the silica film of step (e) to remove surface hydroxyl groups therefrom.

41. A process according to claim 32 in which the silica zeolite is a high-silica zeolite.

42. A process according to claim 32 in which the silica zeolite is a pure-silica MFI zeolite.

43. A process according to claim 32 in which the semiconductor substrate is a silicon wafer or a gallium arsenide wafer.

44. A process according to claim 32 in which the substrate comprises a silicon wafer or a gallium arsenide wafer and one or more metal layers or structures located on said wafer.

45. A semiconductor substrate having at least one silica zeolite film thereon produced by a process according to claim 32.

46. A semiconductor substrate according to claim 45 in which the at least one silica zeolite film is a pure-silica MFI zeolite film.

48. A process according to claim 47 in which the value of x₂ is 0.36, the value of y₂ is 14.29, and the value of z₂ is 11.2.

49. A process according to claim 47 in which the silica source is a C₁-C₂ alkyl orthosilicate.

50. A process according to claim 47 in which the structure-directing agent is a quaternary ammonium hydroxide.

51. A process according to claim 47 in which the silica source is ethyl orthosilicate, the template is tetrapropylammonium hydroxide, and the alkanol is ethanol.

52. A process according to claim 47 in which the silica zeolite is a high-silica zeolite.

53. A process according to claim 47 in which the substrate comprises a silicon wafer or a gallium arsenide wafer and one or more metal layers or structures located on said wafer.

54. A semiconductor substrate having at least one patterned silica zeolite film thereon produced by a process according to claim 47.

55. A semiconductor substrate according to claim 54 in which the at least one patterned silica zeolite film is a pure-silica MFI zeolite film.

56. A continuous bimodal silica zeolite film having a pore volume of from about 0.15 to about 0.21 cm 3/g of micropores having an average pore size of about 5.5 Angstroms and a pore volume of from about 0.1 to about 0.45 cm³/g of mesopores having an average pore size of between about 2 and about 20 nm.

57. A film according to claim 56 in which the mesopores have an average pore size of about 3 nm.

58. A film according to claim 56 in which the pore volume of the mesopores is from about 0.2 to about 0.3 cm³/g.

59. A film according to claim 56 in which the total porosity is about 50%.

60. A semiconductor substrate having at least one film according to claim 56 thereon.

47. A process for producing a patterned silica zeolite film on a semiconductor substrate, comprising:

(a) combining a silica source selected from organic silica sources and inorganic silica sources with an organic hydroxide zeolite-structure-directing agent (SDA), water, and an alkanol selected from ethanol and methanol, to produce a zeolite synthesis composition containing the structure-directing agent, silica source, water and alkanol in a molar ratio of X₃ SDA;

1 silica source;

y₃ H₂O;

z₃ alkanol, wherein the value of x₃ is from about 0.2 to about 0.5, the value of y₃ is from about 10 to about 20, and the value of z₃ is from about 1 to about 30;

(b) heating the composition of step (a) to produce an aqueous colloidal suspension of silica zeolite crystals;

(c) depositing the crystal suspension of step (b) on a semiconductor substrate;

and

(d) drying the crystal suspension at ambient temperature to produce a patterned silica zeolite film.

51-1. A process according to claim 47 in which the silica zeolite is a pure-silica MFI zeolite.

52-2. A process according to claim 47 in which the semiconductor substrate is a silicon wafer or a gallium arsenide wafer.

56-3. A film according to claim 56 in which the mesopores have an average pore size of from about 2 to about 10 nm.