CVD plasma assisted low dielectric constant films

• US 6,287,990 B1
• Filed: 09/29/1998
• Issued: 09/11/2001
• Est. Priority Date: 02/11/1998
• Status: Expired due to Term

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Cheung, David, Yau, Wai-Fan, Mandal, Robert R.
• Primary Examiner(s): MEEKS, TIMOTHY HOWARD
• Application Number:
  US09/162,915
• Time in Patent Office: 1,078 Days
• Field of Search: 427/489, 427/492, 427/497, 427/503, 427/509, 427/515, 427/577, 427/578, 427/579, 427/249.15, 427/255.37, 427/235.6, 438/780, 438/781, 438/789
• US Class Current: 438/780
• CPC Class Codes: C23C 16/401 containing silicon
• 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 21/02208 the precursor containing a compound comprising Si
• CPC Class Codes: H01L 21/02211 the compound being a silane, e.g. disilane, methylsilane or chlorosilane
• 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 21/02274 in the presence of a plasma [PECVD]
• CPC Class Codes: H01L 21/0228 deposition by cyclic CVD, e.g. ALD, ALE, pulsed CVD
• CPC Class Codes: H01L 21/02304 formation of intermediate layers, e.g. buffer layers, layers to improve adhesion, lattice match or diffusion barriers
• CPC Class Codes: H01L 21/02362 formation of intermediate layers, e.g. capping layers or diffusion barriers
• CPC Class Codes: H01L 21/31612 on a silicon body
• CPC Class Codes: H01L 21/76801 characterised by the formation and the after-treatment of the dielectrics, e.g. smoothing
• CPC Class Codes: H01L 21/76808 involving intermediate temporary filling with material
• CPC Class Codes: H01L 21/7681 involving one or more buried masks
• CPC Class Codes: H01L 21/76829 characterised by the formation of thin functional dielectric layers, e.g. dielectric etch-stop, barrier, capping or liner layers
• CPC Class Codes: H01L 21/76832 Multiple layers
• CPC Class Codes: H01L 21/76834 formation of thin insulating films on the sidewalls or on top of conductors H01L21/76831 takes precedence
• CPC Class Codes: H01L 21/76835 Combinations of two or more different dielectric layers having a low dielectric constant H01L21/76832 takes precedence
• CPC Class Codes: H01L 2221/1031 Dual damascene by forming vias in the via-level dielectric prior to deposition of the trench-level dielectric

Abstract

A method and apparatus for depositing a low dielectric constant film by reaction of an organosilane or organosiloxane compound and an oxidizing gas at a low RF power level from 10-250 W. The oxidized organosilane or organosiloxane film has good barrier properties for use as a liner or cap layer adjacent other dielectric layers. The oxidized organosilane or organosiloxane film may also be used as an etch stop or an intermetal dielectric layer for fabricating dual damascene structures. The oxidized organosilane or organosiloxane films also provide excellent adhesion between different dielectric layers. A preferred oxidized organosilane film is produced by reaction of methylsilane, CH₃SiH₃, or dimethylsilane, (CH₃)₂SiH₂, and nitrous oxide, N₂O, at an RF power level from about 10 to 200 W or a pulsed RF power level from about 20 to 250 W during 10-30% of the duty cycle.

Claims

1. A method for depositing a low dielectric constant film on a semiconductor substrate, comprising reacting a compound with an oxidizing gas while applying RF power to deposit the low dielectric constant film on the semiconductor substrate, wherein the compound comprises one or more silicon atoms, at least one alkyl group bonded to each silicon atom, and at least one hydrogen atom bonded to each silicon atom, and wherein the low dielectric constant film has a dielectric constant of about 3 or less, is located between conductive materials on said semiconductor substrate, and retains sufficient silicon-carbon bonds to have a carbon content from about 1% to about 50% by atomic weight.

2. The method of claim 1, wherein the low dielectric constant film is located between interconnect lines.

3. The method of claim 1, wherein the oxidizing gas comprises O₂.

4. The method of claim 1, wherein the oxidizing gas comprises N₂O.

5. The method of claim 1, wherein the oxidizing gas and the compound are reacted at a substrate temperature from about −

20°

C. to about 400°

C.

6. The method of claim 1, wherein the compound has from one to two alkyl groups bonded to each silicon atom.

7. The method of claim 1, wherein the compound comprises methylsilane.

8. The method of claim 1, wherein the low dielectric constant film is annealed.

9. The method of claim 1, wherein the RF power provides a power density of about 0.3 W/cm².

10. The method of claim 1, wherein the RF power is provided by a mixed frequency power source.

11. The method of claim 10, wherein the mixed frequency power source provides high frequency RF power at about 13.56 MHz and low frequency RF power at about 360 KHz to about 1 MHz.

12. The method of claim 1, wherein a dielectric material is deposited on the low dielectric constant film.

13. A method for depositing a low dielectric constant film on a semiconductor substrate, comprising:

reacting a compound and an oxidizing gas at RF plasma conditions sufficient to deposit a low dielectric constant film on the semiconductor substrate, wherein the compound comprises at least one silicon-hydrogen bond and at least one alkyl group bonded to silicon, and wherein the low dielectric constant film retains sufficient silicon-carbon bonds to have a dielectric constant of about 3 or less and a carbon content from about 1% to about 50% by atomic weight;

etching the low dielectric constant film to form openings; and

depositing a conductive material within the openings.

14. The method of claim 13, wherein the oxidizing gas comprises O₂.

15. The method of claim 13, wherein the oxidizing gas comprises N₂O.

16. The method of claim 13, wherein the openings are openings for interconnect lines.

17. The method of claim 13, wherein the RF plasma conditions comprise a power density of about 0.3 W/cm².

18. The method of claim 17, wherein the power density is provided by a mixed frequency power source.

19. The method of claim 18, wherein the mixed frequency power source provides high frequency RF power at about 13.56 MHz and low frequency RF power at about 360 KHz to about 1 MHz.

20. The method of claim 13, wherein the compound has from one to two methyl groups bonded to each silicon.

21. The method of claim 13, wherein the RF plasma conditions comprise a substrate temperature from about −

20°

C. to about 400°

C.

22. The method of claim 13, wherein the compound is methylsilane.

23. The method of claim 13, wherein the low dielectric constant film is annealed.

24. The method of claim 13, wherein a dielectric material is deposited on the low dielectric constant film.

25. The method of claim 13, wherein the conductive material comprises copper.

26. The method of claim 13, wherein the compound has more than one silicon and at least one alkyl group bonded to each silicon.

27. A process for depositing a low dielectric constant film, comprising:

depositing a conformal lining layer on a patterned metal layer on a substrate from process gases comprising a compound and an oxidizing gas while applying RF power, wherein the compound comprises one or more silicon atoms, at least one alkyl group bonded to each silicon atom, and at least one hydrogen atom bonded to each silicon atom, and wherein the conformal lining layer retains sufficient silicon-carbon bonds to have a carbon content from about 1% to about 50% by atomic weight and a dielectric constant of about 3 or less; and

depositing a gap filling layer on the conformal lining layer.

28. The process of claim 27, wherein each silicon atom in the compound is bonded to only one or two alkyl groups.

29. The process of claim 27, wherein the oxidizing gas comprises O₂.

30. The process of claim 27, wherein the oxidizing gas comprises N₂O.

31. The process of claim 27, wherein the gap filling layer is deposited by reaction of methylsilane and hydrogen peroxide.

32. The process of claim 31, further comprising depositing a capping layer on the gap filling layer from process gases comprising the compound and the oxidizing gas.

33. The process of claim 27, wherein the conformal lining layer is deposited at a substrate temperature from about −

20°

C. to about 400°

C.

34. The process of claim 27, wherein the conformal lining layer is deposited on metal lines.

35. The process of claim 27, wherein the conformal lining layer is annealed.

36. A method for depositing a low dielectric constant film on a semiconductor substrate, comprising reacting an organosilane compound comprising at least one hydrogen and at least one alkyl group bonded to silicon with an oxidizing gas at plasma conditions sufficient to deposit a low dielectric constant film on the semiconductor substrate, wherein the low dielectric constant film has a carbon content from 1% to 50% by atomic weight and a dielectric constant of about 3 or less.

37. The method of claim 36, wherein the oxidizing gas comprises O₂.

38. The method of claim 36, wherein the oxidizing gas comprises N₂O.

39. The method of claim 36, wherein the organosilane compound is methylsilane.

40. The method of claim 36, wherein the film is annealed.

41. The method of claim 36, wherein the plasma conditions comprise a power density of about 0.3 W/cm².

42. The method of claim 41, wherein the power density is provided by a mixed frequency power source.

43. The method of claim 42, wherein the mixed frequency power source provides high frequency RF power at about 13.56 MHz and low frequency RF power at about 360 KHz to about 1 MHz.

44. The method of claim 36, wherein the organosilane compound has more than one silicon and at least one alkyl group bonded to each silicon.

45. The method of claim 36, wherein the plasma conditions comprise a substrate temperature from about −

20°

C. to about 400°

C.

46. The method of claim 36, wherein a dielectric material is deposited on the low dielectric constant film.

47. A method for depositing a low dielectric constant film on a semiconductor substrate, comprising reacting an organosilane compound consisting essentially of both CH₃—

Si bonds and Si—

H bonds, with an oxidizing gas at plasma conditions sufficient to deposit a low dielectric constant film on the semiconductor substrate, wherein the low dielectric constant film has a carbon content from 1% to 50% by atomic weight and a dielectric constant of about 3 or less.

48. The method of claim 47, wherein the film is located between conductive lines.

49. The method of claim 47, wherein the plasma conditions comprise a substrate temperature from about −

20°

C. to about 400°

C.

50. The method of claim 47, wherein the plasma conditions comprise a power density of about 0.3 W/cm².

51. The method of claim 50, wherein the power density is provided by a mixed frequency power source.

52. The method of claim 51, wherein the mixed frequency power source provides RF power at a high frequency of about 13.56 MHz and a low frequency of about 360 KHz to about 1 MHz.

53. The method of claim 47, wherein the oxidizing gas comprises O₂.

54. The method of claim 47, wherein the organosilane compound has at least one methyl group bonded to each silicon.

55. The method of claim 47, wherein the oxidizing gas comprises N₂O.

56. The method of claim 47, wherein the organosilane compound has one methyl group.

57. The method of claim 47, wherein the low dielectric constant film is annealed.

58. The method of claim 47, wherein a dielectric material is deposited on the low dielectric constant film.

59. A method for depositing a low dielectric constant film on a semiconductor substrate, comprising reacting an organosilane compound consisting of carbon, silicon, and hydrogen with an oxidizing gas at plasma conditions sufficient to deposit a low dielectric constant film on a semiconductor substrate, wherein the organosilane compound has at least one silicon-hydrogen bond and at least one alkyl group bonded to silicon, and wherein the low dielectric constant film has a carbon content from 1% to 50% by atomic weight and a dielectric constant of about 3 or less.

60. The method of claim 59, wherein the low dielectric constant film is located between conductive lines.

61. The method of claim 59, wherein the plasma conditions comprise a substrate temperature from about −

20°

C. to about 400°

C.

62. The method of claim 59, wherein the plasma conditions comprise a power density of about 0.3 W/cm².

63. The method of claim 62, wherein the power density is provided by a mixed frequency power source.

64. The method of claim 63, wherein the mixed frequency power source provides RF power at a high frequency of about 13.56 MHz and a low frequency of about 360 KHz to about 1 MHz.

65. The method of claim 59, wherein the oxidizing gas comprises oxygen.

66. The method of claim 59, wherein the oxidizing gas comprising N₂O.

67. The method of claim 59, wherein the organosilane compound has one methyl group bonded to each silicon.

68. The method of claim 59, wherein the low dielectric constant film is annealed.

69. The method of claim 59, wherein the organosilane compound has more than one silicon and at least one alkyl group bonded to each silicon.

70. The method of claim 59, wherein a dielectric material is deposited on the low dielectric constant film.