INTERCONNECT STRUCTURES WITH A METAL NITRIDE DIFFUSION BARRIER CONTAINING RUTHENIUM AND METHOD OF FORMING

• US 20080206982A1
• Filed: 02/26/2007
• Published: 08/28/2008
• Est. Priority Date: 02/26/2007
• Status: Active Grant

• Current Assignee: Tokyo Electron Limited
• Original Assignee: Tokyo Electron Limited
• Inventors: Suzuki, Kenji
• Granted Patent: US 7,786,006 B2
• Time in Patent Office: Days
• US Class Current: 438/627
• CPC Class Codes: C23C 16/34 Nitrides C23C16/303 takes precedence
• CPC Class Codes: C23C 16/45529 specially adapted for making a layer stack of alternating different compositions or gradient compositions
• CPC Class Codes: C23C 16/45531 specially adapted for making ternary or higher compositions
• CPC Class Codes: H01L 21/28562 Selective deposition
• CPC Class Codes: H01L 21/76843 formed in openings in a dielectric
• CPC Class Codes: H01L 21/76844 Bottomless liners
• CPC Class Codes: H01L 21/76846 Layer combinations
• CPC Class Codes: H01L 21/76873 for electroplating
• CPC Class Codes: H01L 2221/1089 Stacks of seed layers

Abstract

A method for forming an interconnect structure for copper metallization and an interconnect structure containing a metal nitride diffusion barrier are described. The method includes providing a substrate having a micro-feature opening formed within a dielectric material and forming a metal nitride diffusion barrier containing ruthenium, nitrogen, and a nitride-forming metal over the surfaces of the micro-feature. The nitride-forming metal is selected from Groups IVB, VB, VIB, and VIIB of the Periodic Table, and the metal nitride diffusion barrier is formed by exposing the substrate to a precursor of the nitride-forming metal, a nitrogen precursor, and a ruthenium precursor.

Claims

1. A method for forming an interconnect structure, the method comprising:

providing a substrate having a micro-feature opening formed within a dielectric material, the micro-feature opening having a sidewall surface and a bottom surface; and

exposing the substrate to a precursor of a nitride-forming metal, a nitrogen precursor, and a ruthenium precursor to form a metal nitride diffusion barrier comprising ruthenium, nitrogen, and the nitride-forming metal over the sidewall and bottom surfaces of the micro-feature.

2. The method of claim 1, wherein the nitride-forming metal is selected from Groups IVB, VB, VIB, and VIIB of the Periodic Table.

3. The method of claim 1, wherein the exposing comprises a deposition process selected from atomic layer deposition, plasma enhanced atomic layer deposition, chemical vapor deposition, pulsed chemical vapor deposition, plasma enhanced chemical vapor deposition, or a combination thereof.

4. The method of claim 1, wherein the exposing further comprises varying a ratio of the precursor of the nitride-forming metal and the ruthenium precursor during the exposing.

5. The method of claim 4, wherein the ratio is varied between a first ratio corresponding to substantially pure precursor of the nitride-forming metal and a second ratio corresponding to substantially pure ruthenium precursor.

6. The method of claim 1, wherein the exposing comprises:

sequentially, in any order, exposing the substrate to the precursor of the nitride-forming metal, the nitrogen precursor, and the ruthenium precursor.

7. The method of claim 1, wherein the ruthenium precursor comprises a ruthenium carbonyl precursor or a ruthenium organometallic precursor.

8. The method of claim 1, wherein the precursor of the nitride-forming metal and the ruthenium precursors comprise carbonyl precursors.

9. The method of claim 1, wherein the nitrogen precursor comprises ammonia, hydrazine, or C1-C10 hydrazine.

10. The method of claim 1, wherein the metal nitride diffusion barrier has a variable Ru content across a thickness thereof.

11. The method of claim 1, wherein a thickness of the metal nitride diffusion barrier is less than about 3 nm.

12. The method of claim 1, wherein the exposing comprises:

a) exposing the substrate to a gas pulse comprising the precursor of the nitride-forming metal;

b) exposing the substrate to a gas pulse comprising the nitrogen precursor;

c) exposing the substrate to a gas pulse comprising the ruthenium precursor;

d) exposing the substrate to a gas pulse comprising the nitrogen precursor; and

e) repeating steps a)-d) a predetermined number of times.

13. The method of claim 12, wherein performing steps a)-d) comprises sequentially performing steps a) and b) a first number of times prior to performing steps c) and d), and sequentially performing steps c) and d) a second number of times prior to repeating in step e).

14. The method of claim 13, wherein the first number of times, the second number of times, or both the first and second number of times is varied during the deposition of the metal nitride diffusion barrier.

15. The method of claim 12, wherein steps a) and b) have at least partial temporal overlap, steps c) and d) have at least partial temporal overlap, or steps a) and b) have at least partial temporal overlap and steps c) and d) have at least partial temporal overlap.

16. The method of claim 1, wherein the micro-feature comprises a via, a trench, or a combination thereof.

17. The method of claim 1, further comprising, after the exposing:

filling the micro-feature with Cu.

18. The method of claim 17, further comprising:

depositing a seed layer over the metal nitride diffusion barrier prior to the filling, the seed layer comprising Cu or Ru.

19. The method of claim 18, further comprising:

removing the metal nitride diffusion barrier, the seed layer, or both the metal nitride diffusion barrier and the seed layer from the bottom surface of the micro-feature prior to the filling.

20. The method of claim 1, wherein the exposing comprises:

exposing the substrate to the precursor of the nitride-forming metal, the ruthenium precursor, and a carrier gas containing the nitrogen precursor and CO gas.

21. A method for forming an interconnect structure, the method comprising:

providing a substrate having a micro-feature opening formed within a dielectric material, the micro-feature opening having a sidewall surface and a bottom surface;

exposing the substrate to a carbonyl precursor of a nitride-forming metal, a nitrogen precursor, Ru₃(CO)₁₂, and CO carrier gas to form a metal nitride diffusion barrier comprising ruthenium, nitrogen, and the nitride-forming metal over the sidewall and bottom surfaces of the micro-feature, wherein the nitride-forming metal is selected from Groups IVB, VB, VIB, and VIIB of the Periodic Table;

removing the metal nitride diffusion barrier from the bottom surface of the micro-feature;

then, depositing a seed layer comprising Cu or Ru over the sidewall and bottom surfaces of the micro-feature; and

then, filling the micro-feature with Cu.

22. A method for forming an interconnect structure, the method comprising:

providing a substrate having a micro-feature opening formed within a dielectric material, the micro-feature opening having a sidewall surface and a bottom surface;

exposing the substrate to a carbonyl precursor of a nitride-forming metal, a nitrogen precursor, Ru₃(CO)₁₂, and CO carrier gas to form a metal nitride diffusion barrier comprising ruthenium, nitrogen, and the nitride-forming metal over the sidewall and bottom surfaces of the micro-feature, wherein the nitride-forming metal is selected from Groups IVB, VB, VIB, and VIIB of the Periodic Table;

depositing a Ru seed layer over the metal nitride diffusion barrier;

removing the metal nitride diffusion barrier and the Ru seed layer from the bottom surface of the micro-feature; and

then, filling the micro-feature with Cu.

23. The method of claim 22, further comprising:

depositing a Cu seed layer over the sidewall and bottom surfaces of the micro-feature prior to the filling.

24. An interconnect structure, comprising:

a micro-feature opening formed within a dielectric material, the micro-feature having a sidewall surface and a bottom surface;

a metal nitride diffusion barrier on the sidewall surface of the micro-feature and comprising ruthenium, nitrogen and a nitride-forming metal selected from Groups IVB, VB, VIB, and VIIB of the Periodic Table; and

Cu filling the micro-feature.

25. The interconnect structure of claim 24, further comprising a Ru or Cu seed layer on the metal nitride diffusion barrier in the micro-feature.

26. The interconnect structure of claim 24, further comprising the metal nitride diffusion barrier on the bottom surface of the micro-feature.

27. The interconnect structure of claim 24, wherein the metal nitride diffusion barrier has a variable Ru content across a thickness thereof.

28. The interconnect structure of claim 24, wherein a thickness of the metal nitride diffusion barrier is less than about 3 nm.

29. The interconnect structure of claim 24, wherein the micro-feature comprises a via, a trench, or a combination thereof.

30. The interconnect structure of claim 24, wherein the bottom surface of the micro-feature comprises a conductive interconnect structure.

31. The interconnect structure of claim 24, wherein a ratio of the nitride-forming metal and ruthenium varies across a thickness of the metal nitride diffusion barrier.

32. The interconnect structure of claim 31, wherein the ratio varies between a first ratio corresponding to substantially pure nitride-forming metal and a second ratio corresponding to substantially pure ruthenium.