Method of depositing low k films using an oxidizing plasma

• US 6,593,247 B1
• Filed: 04/19/2000
• Issued: 07/15/2003
• Est. Priority Date: 02/11/1998
• Status: Expired due to Term

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Lu, Yung-Cheng, Xia, Li-Qun, Yieh, Ellie, Yau, Wai-Fan, Lee, Ju-Hyung, Liu, Kuowei, Huang, Tzu-Fang, Moghadam, Farhad K., Willecke, Ralf B., Ma, Yeming Jim, Cheung, David W.
• Primary Examiner(s): Niebling, John F.
• Assistant Examiner(s): Luk, Olivia T
• Application Number:
  US09/553,461
• Time in Patent Office: 1,182 Days
• Field of Search: 438/758, 438/759, 438/760, 438/623, 438/638, 438/789, 438/780, 257/642, 257/635
• US Class Current: 438/758
• CPC Class Codes: C23C 16/045 Coating cavities or hollow spaces, e.g. interior of tubes; Infiltration of porous substrates
• 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 21/02274 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 21/31633 Deposition of carbon doped silicon oxide, e.g. SiOC
• 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 21/76829 characterised by the formation of thin functional dielectric layers, e.g. dielectric etch-stop, barrier, capping or liner layers
• CPC Class Codes: H01L 21/76835 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 silicon oxide layer is produced by plasma enhanced oxidation of an organosilicon compound to deposit films having a carbon content of at least 1% by atomic weight. Films having low moisture content and resistance to cracking are deposited by introducing oxygen into the processing chamber at a flow rate of less than or equal to the flow rate of the organosilicon compounds, and generating a plasma at a power density ranging between 0.9 W/cm² and about 3.2 W/cm². An optional carrier gas may be introduced to facilitate the deposition process at a flow rate less than or equal to the flow rate of the organosilicon compounds. The organosilicon compound preferably has 2 or 3 carbon atoms bonded to each silicon atom, such as trimethylsilane, (CH₃)₃SiH. An oxygen rich surface may be formed adjacent the silicon oxide layer by temporarily increasing oxidation of the organosilicon compound.

Claims

1. A process for depositing a low dielectric constant film, comprising oxidizing one or more oxygen-free organosilicon compounds at a RF power density of at least about 0.03 W/cm² to deposit a film having a carbon content of at least 1% by atomic weight, wherein oxidizing gases have a flow rate of less than or equal to the flow rate of the one or more oxygen-free organosilicon compounds.

2. The process of claim 1, wherein the low dielectric constant film has an atomic ratio of carbon to silicon (C:

Si) of less than about 1;

1.

3. The process of claim 1, wherein the low dielectric constant film has an atomic ratio of carbon to silicon (C:

Si) between about 1;

4 and about 3;

4.

4. The process of claim 1, wherein the one or more oxygen-free organosilicon compounds have a flow rate of between about 5 sccm and about 1000 sccm.

5. The process of claim 1, wherein the one or more oxygen-free organosilicon compounds are reacted with oxygen in the absence of a carrier gas.

6. The process of claim 1, wherein each silicon atom in the one or more oxygen-free organosilicon compounds is bonded to at least two carbon atoms, and wherein two or more silicon atoms in the same molecule are separated by no more than two carbon atoms.

7. The process of claim 1, wherein the one or more oxygen-free organosilicon compounds are selected from a group consisting of dimethylsilane, trimethylsilane, tetramethylsilane, diphenylsilane, methylphenylsilane, bis(methyl-silano)methane, 1,2-bis(methylsilano)ethane, 1,3,5-trisilano-2,4,6-trimethylene, fluorinated carbon derivatives thereof, and combinations thereof.

8. The process of claim 1, wherein the one or more oxygen-free organosilicon compounds has two or more methyl groups bonded to each silicon atom.

9. The process of claim 1, wherein the one or more oxygen-free organosilicon compounds are selected from the group consisting of dimethylsilane, trimethylsilane, 1,2-bis(methylsilano)ethane, fluorinated carbon derivatives thereof, and combinations thereof.

10. The process of claim 1, wherein the low dielectric constant film is deposited at a temperature of between about 10°

C. and about 500°

C.

11. The process of claim 1, wherein the one or more oxygen-free organosilicon compounds have a carbon to silicon atomic ratio of at least about 2:

1.

12. The process of claim 11, wherein the one or more oxygen-free organosilicon compounds are selected from the group consisting of dimethylsilane, trimethylsilane, and combinations thereof.

13. The process of claim 1, wherein the one or more oxygen-free organosilicon compounds have a carbon to silicon atomic ratio of 3:

1.

14. The process of claim 13, wherein the oxygen-free organosilicon compound is trimethylsilane.

15. The process of claim 4, further comprising a carrier gas having a flow rate less than or equal to the flow rate of the one or more oxygen-free organosilicon compounds.

16. The process of claim 1, wherein oxygen has a flow rate of less than or equal to about 200 sccm.

17. The process of claim 1, wherein the RF power density is between about 0.9 W/cm² and about 3.2 W/cm².

18. The process of claim 1, wherein the film is deposited at a chamber pressure of between about 0.2 Torr and about 20 Torr.

19. The process of claim 10, wherein the film is deposited at a temperature of between about 300°

C. and about 450°

C.

20. The process of claim 1, further comprising forming an oxide rich surface adjacent the low dielectric constant film.

21. The process of claim 20, wherein forming the oxide rich surface comprises introducing oxygen into a processing chamber and generating a plasma.

22. The process of claim 21, wherein the oxygen has a flow rate of less than 2000 sccm and the plasma is generated at a power density of between about 1.43 W/cm² and about 3.2 W/cm².

23. The process of claim 20, wherein the low dielectric constant film is exposed to the plasma between about 5 seconds and about 60 seconds.

24. A process for depositing a low dielectric constant film, comprising oxidizing one or more oxygen-free organosilicon compounds containing carbon with an oxidizing gas disassociated at a power density of greater than about 0.03 W/cm², wherein the oxidizing gas has a flow rate of less than or equal to the flow rate of the oxygen-free organosilicon compounds and a carrier gas has a flow rate less than or equal to the flow rate of the oxygen-free organosilicon compounds at conditions sufficient to deposit a silicon oxide film having an atomic ratio of carbon to silicon (C:

Si) of greater than or equal to about 1;

9.

25. The process of claim 24, wherein the atomic ratio of carbon to silicon (C:

Si) is less than about 1;

1 in the film.

26. The process of claim 24, wherein the atomic ratio of carbon to silicon (C:

Si) is between about 1;

4 and about 3;

4 in the film.

27. The process of claim 24, wherein the oxidizing gas is selected from a group consisting of oxygen, nitrous oxide, carbon dioxide, carbon monoxide, and water vapor, and combinations thereof.

28. The process of claim 27, wherein the oxidizing gas is oxygen.

29. The process of claim 24, wherein each silicon atom in the one or more oxygen-free organosilicon compounds is bonded to at least one carbon atom, and wherein two or more silicon atoms in the same molecule are separated by no more than two carbon atoms or by no more than one oxygen atom.

30. The process of claim 29, wherein the one or more oxygen-free organosilicon compounds are selected from a group consisting of dimethylsilane, trimethylsilane, bis(methylsilano)methane, 1,2-bis(methylsilano)ethane, 1,3,5-trisilano-2,4,6-trimethylene, fluorinated carbon derivatives thereof, and combinations thereof.

31. The process of claim 24, wherein the one or more oxygen-free organosilicon compounds have one or more methyl groups.

32. The process of claim 24, wherein the one or more oxygen-free organosilicon compounds are selected from the group consisting of methylsilane, dimethylsilane, trimethylsilane, and combinations thereof.

33. The process of claim 24, wherein the one or more oxygen-free organosilicon compounds have a carbon to silicon atomic ratio of at least about 2:

1.

34. The process of claim 29, wherein the one or more oxygen-free organosilicon compounds are selected from the group consisting of dimethylsilane, trimethylsilane, 1,2-bis(methylsilano)ethane, fluorinated carbon derivatives thereof, and combinations thereof.

35. The process of claim 25, wherein the one or more organosilicon compounds have a carbon to silicon atomic ratio of at least about 3:

1.

36. The process of claim 35 wherein the oxygen-free organosilicon compound is trimethylsilane.

37. The process of claim 24, wherein the low dielectric constant film is deposited at a temperature of between about 300°

C. and about 450°

C.

38. The process of claim 24, wherein the low dielectric constant film is deposited at a processing chamber pressure of between about 0.2 Torr and about 20 Torr.

39. The process of claim 24, wherein the power is provided at a power density ranging between about 0.9 W/cm² and about 3.2 W/cm².

40. The process of claim 24, wherein the one or more oxygen-free organosilicon compounds have a flow rate of between about 5 sccm and about 1000 sccm.

41. The process of claim 24, wherein oxygen has a flow rate of less than or equal to about 200 sccm.

42. The process of claim 24, further comprising forming an oxide rich surface adjacent the low dielectric constant film.

43. The process of claim 42, wherein forming the oxide rich surface comprises introducing oxygen into a processing chamber and generating a plasma.

44. The process of claim 43, wherein the oxygen has a flow rate of less than 2000 sccm and the plasma is generated at a power density ranging between about 1.4 W/cm² and about 3.2 W/cm².

45. The process of claim 44, wherein the low dielectric constant film is exposed to the plasma between about 5 seconds and about 60 seconds.

46. A process for depositing a low dielectric constant film, comprising reacting one or more oxygen-free organosilicon compounds that contain a carbon to silicon atomic ratio of at least about 2:

1 with an oxidizing gas disassociated at a power density ranging between about 0.9 W/cm² and about 3.2 W/cm², wherein the oxidizing gas has a flow rate of less than or equal to the flow rate of the oxygen-free organosilicon compounds at conditions sufficient to deposit a film having an atomic ratio of carbon to silicon (C;

Si) of between about 1;

9 and less than about 1;

1.

47. The process of claim 46, wherein the atomic ratio of carbon to silicon (C:

Si) is between about 1;

4 and about 3;

4 in the film.

48. The process of claim 46, wherein the one or more oxygen-free organosilicon compounds are selected from a group consisting of dimethylsilane, trimethylsilane, 1,2-bis(methylsilano)ethane, fluorinated carbon derivatives thereof, and combinations thereof.

49. The process of claim 48, wherein the oxygen-free organosilicon compound is dimethylsilane.

50. The process of claim 46, wherein the one or more oxygen-free organosilicon compounds have a carbon to silicon atomic ratio of at least about 3:

1.

51. The process of claim 50, wherein the oxygen-free organosilicon compound is trimethylsilane.

52. The process of claim 46, wherein the oxidizing gas is selected from a group consisting of oxygen, nitrous oxide, carbon dioxide, carbon monoxide, and water vapor, and combinations thereof.

53. The process of claim 46, wherein the oxidizing gas is oxygen.

54. The process of claim 46, wherein the low dielectric constant film is deposited at a temperature of between about 300°

C. and about 450°

C.

55. The process of claim 46, wherein the low dielectric constant film is deposited at a processing chamber pressure of between about 0.2 Torr and about 20 Torr.

56. The process of claim 46, wherein the RF power density is provided at between about 0.9 W/cm² and about 3.2 W/cm².

57. The process of claim 46, wherein the one or more oxygen-free organosilicon compounds have a flow rate of between about 5 sccm and about 1000 sccm.

58. The process of claim 46, wherein oxygen has a flow rate of less than or equal to about 200 sccm.

59. The process of claim 46, further comprising a carrier gas having a flow rate less than or equal to the flow rate of the one or more oxygen-free organosilicon compounds.

60. The process of claim 46, further comprising forming an oxide rich surface adjacent the low dielectric constant film.

61. The process of claim 60, wherein forming the oxide rich surface comprises introducing oxygen into a processing chamber and generating a plasma.

62. The process of claim 61, wherein the oxygen has a flow rate of less than 2000 sccm and the plasma is generated at a power density of between preferably between about 1.43 W/cm² and about 3.2 W/cm².

63. The process of claim 62, wherein the low dielectric constant film is exposed to the plasma between about 5 seconds and about 60 seconds.