Process for forming a low dielectric constant carbon-containing film

• US 6,632,478 B2
• Filed: 02/22/2001
• Issued: 10/14/2003
• Est. Priority Date: 02/22/2001
• Status: Expired due to Fees

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Xia, Li-Qun, Gaillard, Frederic, Yieh, Ellie, Shu, Jen, Lim, Tian-Hoe
• Primary Examiner(s): Chen, Bret
• Application Number:
  US09/791,989
• Publication Number:
  US 20020164429A1
• Time in Patent Office: 964 Days
• Field of Search: 427/255.37, 427/255.31, 427/376.2, 427/372.2, 427/533, 427/535, 427/249.1
• US Class Current: 427/255.37
• CPC Class Codes: B05D 1/60 Deposition of organic layers from vapour phase vapour phase deposition in general C23C14/00, C23C16/00
• CPC Class Codes: C23C 16/401 containing silicon
• CPC Class Codes: C23C 16/56 After-treatment
• 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 21/02211 the compound being a silane, e.g. disilane, methylsilane or chlorosilane
• CPC Class Codes: H01L 21/02274 in the presence of a plasma [PECVD]
• CPC Class Codes: H01L 21/02337 treatment by exposure to a gas or vapour
• CPC Class Codes: H01L 21/0234 treatment by exposure to a plasma
• CPC Class Codes: H01L 21/02362 formation of intermediate layers, e.g. capping layers or diffusion barriers
• CPC Class Codes: H01L 21/3146 Carbon layers, e.g. diamond-like layers
• CPC Class Codes: H01L 21/31633 Deposition of carbon doped silicon oxide, e.g. SiOC

Abstract

An embodiment of the present invention provides methods for forming a carbon-containing layer having a low dielectric constant and good gap-fill capabilities. A method includes depositing a carbon-containing layer on a substrate and transforming the carbon-containing layer to remove at least some of the carbon. The transforming step may include annealing the carbon-containing layer in a furnace containing a hydrogen atmosphere, for example. The carbon-containing layer may be a carbon-doped silicon oxide material, where the transforming step changes the carbon-doped silicon oxide. Additionally, the method may include subjecting the annealed layer to a hydrogen and/or low oxygen plasma treatment to further remove carbon from the layer. Additionally, a step of adding a capping layer to the annealed, plasma treated material is provided. Products made by the above methods are also included, such as a product including a low k carbon-containing layer where the low k carbon-containing layer has been transformed to remove some of the carbon from the layer. An additional product includes a transformed carbon-containing layer further subjected to a hydrogen plasma treatment to remove more carbon from the layer. Further, a capping layer deposited over the transformed and hydrogen plasma treated layer is provided.

Claims

1. A method of forming a low k dielectric film on a substrate, the method comprising:

depositing a carbon-containing dielectric film over the substrate by flowing a process gas comprising ozone and a gas comprising an organosilane having at least one silicon-carbon bond into a processing chamber in which the substrate is disposed;

thereafter, annealing the carbon-containing dielectric film by heating the substrate while exposing the substrate to a flow of a hydrogen source; and

thereafter, exposing the annealed carbon-containing dielectric film to dissociated species formed from a plasma formed from a hydrogen source;

wherein the carbon-containing dielectric film has a first dielectric constant after it is initially deposited, a second dielectric constant that is less than the first dielectric constant after it is annealed and a third dielectric constant that is less than the second dielectric constant after it is exposed to the dissociated hydrogen species.

2. The method of claim 1 wherein the said organosilane is selected from the group consisting of methysilanes, dimethylsilanes, trimethylsilanes, tetramethylsilanes and phenylmethylsilanes.

3. The method of claim 1 wherein said carbon containing layer is a carbon-doped silicon oxide layer.

4. The method of claim 1 wherein the carbon containing dielectric layer is deposited at a temperature less than about 350°

C. and at a pressure between about 1 to 760 torr.

5. The method of claim 4 wherein the carbon containing dielectric layer is deposited at a temperature less than about 250°

C. and at a pressure between about 10 to 500 torr.

6. The method of claim 4 wherein the carbon containing dielectric layer is deposited at a temperature less than about 150°

C.

7. The method of claim 1 wherein during the annealing step the carbon containing dielectric film is exposed to a flow of a hydrogen gas at a flow rate between about 500 to 3000 sccm while being heated to a temperature of between about 250°

C. to about 550°

C. in an atmosphere having a pressure of between 100 to 760 torr.

8. The method of claim 7 wherein the annealing step is performed at a temperature of between about 350°

C. to about 450°

C.

9. The method of claim 1 further comprising flowing an inert gas along with the hydrogen source during the annealing step.

10. The method of claim 1 further comprising flowing an inert gas along with the process gas during the depositing step.

11. The method of claim 1 further comprising flowing a nitrogen source along with the hydrogen source during the annealing step.

12. The method of claim 11 wherein the hydrogen source comprises one of H₂, NH₃ and TMS, and wherein the nitrogen source comprises one of N₂ and NH₃.

13. The method of claim 11 wherein the annealing step flows a gaseous mixture comprising about 1 to 10% H₂ and 90 to 99% N₂ by volume.

14. The method of claim 1 wherein the plasma is formed from a nitrogen source along with the hydrogen source.

15. The method of claim 14 wherein the nitrogen and hydrogen sources are a single source.

16. The method of claim 15 wherein the single source is NH₃.

17. The method of claim 15 wherein the carbon containing dielectric film is exposed to the dissociated species for between about 10 to 300 seconds during the exposing step.

18. The method of claim 17 wherein the carbon containing dielectric film is exposed to the dissociated species for between about 20 to 60 seconds during the exposing step.

19. The method of claim 1 wherein a flow rate of the hydrogen source into the plasma is between about 250 to 2000 sccm.

20. The method of claim 19 wherein the flow rate of the hydrogen source into the plasma is between about 500 to 1000 sccm.

21. The method of claim 1 wherein the plasma is formed in a chamber maintained at a temperature between about 300°

C. to about 500°

C. and at a pressure of between about 1 to 100 torr during the exposing step.

22. The method of claim 21 wherein the chamber is maintained at a temperature between about 400°

C. to about 500°

C. and at a pressure between about 50 to 100 torr during the step.

23. The method of claim 1 wherein the dissociated species are formed in a plasma chamber by applying RF energy at a power up to about 2000 Watts.

24. The method of claim 23 wherein the dissociated species are formed in a plasma chamber by applying said RF energy at a power of between about 200 to 300 Watts.

25. The method of claim 1 further comprising capping the carbon-containing dielectric film after the exposing step wit a capping layer.

26. The method of claim 25 wherein the capping layer is deposited from a capping gas comprising TMS.

27. The method of claim 26 wherein the capping gas further comprises NH₃.

28. The method of claim 25 wherein the capping layer is deposited from a capping gas comprising NH₃.

29. The method of claim 25 wherein the capping layer has at least one Si N bond.

30. The method of claim 25 wherein the capping layer has at least one Si C bond.

31. The method of claim 1, further comprising capping the layer after completion of said annealing, said capping comprising the steps of:

flowing helium and a capping gas into a processing chamber containing the substrate and layer; and

reacting the helium with the capping gas to form a capping layer on the carbon-containing layer on the substrate.

32. The method of claim 1 wherein the second dielectric constant is between about 2.5 and 3.0.

33. The method of claim 32 wherein the third dielectric constant is less than about 2.2.

34. The method of claim 33 wherein a difference between the first dielectric constant and the second dielectric constant is 14 or greater.

35. The method of claim 34 wherein the first dielectric constant is about 17.

36. The method of claim 1 wherein the annealing step takes place in a vacuum furnace.

37. A method of forming a low k dielectric film on a substrate, the method comprising:

depositing a carbon-doped silicon oxide film over the substrate in a thermal CVD process by flowing a process gas comprising ozone and a gas comprising an organosilane having at least one silicon-carbon bond into a processing chamber in which the substrate is disposed and heating the substrate to a temperature less than 250°

C. while maintaining the substrate processing chamber at a pressure of between about 10 and 500 Torr;

thereafter, annealing the carbon-doped silicon oxide film by heating the substrate to a temperature between about 250 to 550°

C. while exposing the substrate to a flow of a hydrogen source; and

thereafter, exposing the annealed carbon-doped silicon oxide film to dissociated species formed from a plasma formed from a hydrogen source;

wherein the carbon-doped silicon oxide film has a first density and a first dielectric constant after it is initially deposited, a second density and a second dielectric constant after it is annealed that are less than the first density and first dielectric constant, respectively, and a third density and a third dielectric constant after it is exposed to the dissociated hydrogen species that are the second dielectric constant respectively.

38. The method of claim 37 wherein the second dielectric constant is between about 2.5 and 3.0.

39. The method of claim 38 wherein the second density is between about 1.10 and 1.30 g/cm³.

40. The method of claim 38 wherein the third dielectric constant is less than about 2.2.

41. The method of claim 40 wherein a difference between the first dielectric constant and the second dielectric constant is 14 or greater.

42. The method of claim 41 wherein the first dielectric constant is about 17.

43. The method of claim 37 wherein the first density is between about 1.20 and 1.40 g/cm³.

44. A method of forming a low k dielectric film on a substrate, the method comprising:

depositing a carbon-doped silicon oxide film over the substrate in a thermal CVD process by flowing a process gas comprising ozone and a gas comprising an organosilane having at least one silicon-carbon bond into a processing chamber in which the substrate is disposed and heating the substrate to a temperature less than 250°

C. while maintaining the substrate processing chamber at a pressure of between about 10 and 500 Torr;

thereafter, annealing the carbon-doped silicon oxide film to reduce the film'"'"'s dielectric constant and increase its porosity by heating the substrate to a temperature between about 250 to 550°

C. while exposing the substrate to a flow of a hydrogen source;

thereafter, exposing the annealed carbon-doped silicon oxide film to dissociated species formed from a plasma formed from a hydrogen source to further reduce the film'"'"'s dielectric constant and further increase the film'"'"'s porosity;

wherein a carbon content of the carbon-doped silicon oxide film is decreased in the annealing further decreased in the exposing step.

45. The method of claim 44 wherein the hydrogen source used in the annealing step comprises H₂.

46. The method of claim 45 wherein the hydrogen source used in the exposing step comprises H₂.