Method of using scatterometry for analysis of electromigration, and structures for performing same

• US 6,881,594 B1
• Filed: 10/28/2002
• Issued: 04/19/2005
• Est. Priority Date: 10/28/2002
• Status: Expired due to Fees

• Current Assignee: GlobalFoundries, Inc.
• Original Assignee: Advanced Micro Devices, Inc.
• Inventors: Nariman, Homi E., Stirton, James Broc, Lensing, Kevin R., Reeves, Steven P.
• Primary Examiner(s): PERT, EVAN T
• Application Number:
  US10/281,666
• Time in Patent Office: 904 Days
• Field of Search: 438/14, 438 16- 18, 438/466, 438/468, 702/155, 702/167, 702/172
• US Class Current: 438/14
• CPC Class Codes: G01N 2021/1721 Electromodulation
• CPC Class Codes: G01N 21/1717 with a modulation of one or more physical properties of the sample during the optical investigation, e.g. electro-reflectance
• CPC Class Codes: G01N 21/47 Scattering, i.e. diffuse reflection G01N21/25, G01N21/41 take precedence G01N21/55 takes precedence

Abstract

The present invention is generally directed to various methods of using scatterometry for analysis of electromigration. In one illustrative embodiment, the method comprises forming a grating structure above a semiconducting substrate, the grating structure being comprised of a plurality of conductive structures, forcing an electrical current through at least one of the conductive structures and performing scatterometric measurements of at least one conductive structure to detect a change in shape of at least a portion of the conductive structure. In further embodiments, the method comprises determining a susceptibility of at least one conductive structure to electromigration based upon the detected change in shape of the conductive structure.

Claims

1. A method of performing electromigration analysis, comprising:

forming a grating structure above a semiconducting substrate, said grating structure being comprised of a plurality of conductive structures;

forcing an electrical current through at least one of said conductive structures; and

performing scatterometric measurements of said at least one conductive structure to detect a change in shape of at least a portion of said at least one conductive structure.

2. The method of claim 1, wherein said conductive structures are conductive metal lines.

3. The method of claim 1, wherein each of said conductive structures is comprised of a conductive metal line and at least one cap layer positioned above and below said conductive metal line.

4. The method of claim 1, wherein each of said conductive structures is comprised of a first metal line and a second metal line that are spaced apart from one another by a conductive contact that is conductively coupled to each of said first and second metal lines.

5. The method of claim 1, wherein each of said conductive structures is comprised of at least one of aluminum, copper, tungsten and titanium.

6. The method of claim 1, wherein said grating structure occupies approximately 10,000 μ

m² of surface area.

7. The method of claim 1, wherein said grating structure is comprised of approximately 100-700 conductive structures.

8. The method of claim 1, wherein performing scatterometric measurements comprises illuminating said at least one conductive structure and measuring light reflected therefrom.

9. The method of claim 1, wherein said scatterometric measurements are performed on at least a corner region of said at least one conductive structure.

10. The method of claim 1, further comprising determining a susceptibility of said at least one conductive structure to electromigration based upon said detected change in shape of said at least one conductive structure.

11. The method of claim 1, wherein said scatterometric measurements are performed while said electrical current is being forced through said at least one conductive structure.

12. The method of claim 1, wherein said scatterometric measurements are performed after stopping said electrical current.

13. The method of claim 1, further comprising determining a rate of change of said shape of said at least one conductive structure and using said determined rate of change of said shape of said at least one conductive structure to predict the susceptibility of said at least one conductive structure to electromigration.

14. A method of performing electromigration analysis, comprising:

forming a grating structure above a semiconducting substrate, said grating structure being comprised of a plurality of conductive structures;

forcing an electrical current through at least one of said conductive structures;

performing scatterometric measurements of said at least one conductive structure while said electrical current is being forced through said at least one conductive structure to detect a change in shape of at least a portion of said at least one conductive structure; and

determining a susceptibility of said at least one conductive structure to electromigration based upon said detected change in shape of said at least one conductive structure.

15. The method of claim 14, wherein said conductive structures are conductive metal lines.

16. The method of claim 14, wherein each of said conductive structures is comprised of a conductive metal line and at least one cap layer positioned above and below said conductive metal line.

17. The method of claim 14, wherein each of said conductive structures is comprised of a first metal line and a second metal line that are spaced apart from one another by a conductive contact that is conductively coupled to each of said first and second metal lines.

18. The method of claim 14, wherein each of said conductive structures is comprised of at least one of aluminum, copper, tungsten and titanium.

19. The method of claim 14, wherein said grating structure occupies approximately 10,000 μ

m² of surface area.

20. The method of claim 14, wherein said grating structure is comprised of approximately 100-700 conductive structures.

21. The method of claim 14, wherein performing scatterometric measurements comprises illuminating said at least one conductive structure and measuring light reflected therefrom.

22. The method of claim 14, wherein said scatterometric measurements are performed on at least a corner region of said conductive structure.

23. The method of claim 14, further comprising determining a rate of change of said shape of said at least one conductive structure and using said determined rate of change of said shape of said at least one conductive structure to predict the susceptibility of said at least one conductive structure to electromigration.

24. A method of performing electromigration analysis, comprising:

forming a grating structure above a semiconducting substrate, said grating structure being comprised of a plurality of conductive structures;

forcing an electrical current through at least one of said conductive structures;

after stopping said electrical current, performing scatterometric measurements of said at least one conductive structure to detect a change in shape of at least a portion of said at least one conductive structure; and

determining a susceptibility of said at least one conductive structure to electromigration based upon said detected change in shape of said at least one conductive structure.

25. The method of claim 24, wherein said conductive structures are conductive metal lines.

26. The method of claim 24, wherein each of said conductive structures is comprised of a conductive metal line and at least one cap layer positioned above and below said conductive metal line.

27. The method of claim 24, wherein each of said conductive structures is comprised of a first metal line and a second metal line that are spaced apart from one another by a conductive contact that is conductively coupled to each of said first and second metal lines.

28. The method of claim 24, wherein each of said conductive structures is comprised of at least one of aluminum, copper, tungsten and titanium.

29. The method of claim 24, wherein said grating structure occupies approximately 10,000 μ

m² of surface area.

30. The method of claim 24, wherein said grating structure is comprised of approximately 100-700 conductive structures.

31. The method of claim 24, wherein performing scatterometric measurements comprises illuminating said at least one conductive structure and measuring light reflected therefrom.

32. The method of claim 24, wherein said scatterometric measurements are performed on at least a corner region of said conductive structure.

33. The method of claim 24, further comprising determining a rate of change of said shape of said at least one conductive structure and using said determined rate of change of said shape of said at least one conductive structure to predict the susceptibility of said at least one conductive structure to electromigration.

34. A method of performing electromigration analysis, comprising:

forming a grating structure above a semiconducting substrate, said grating structure being comprised of a plurality of conductive structures;

forcing an electrical current through at least one of said conductive structures;

performing scatterometric measurements of said at least one conductive structure to detect a change in shape of at least a portion of said at least one conductive structure; and

determining a rate of change of said shape of said at least one conductive structure and using said determined rate of change of said shape of said at least one conductive structure to predict the susceptibility of said at least one conductive structure to electromigration.

35. The method of claim 34, wherein said conductive structures are conductive metal lines.

36. The method of claim 34, wherein each of said conductive structures is comprised of a conductive metal line and at least one cap layer positioned above and below said conductive metal line.

37. The method of claim 34, wherein each of said conductive structures is comprised of a first metal line and a second metal line that are spaced apart from one another by a conductive contact that is conductively coupled to each of said first and second metal lines.

38. The method of claim 34, wherein each of said conductive structures is comprised of at least one of aluminum, copper, tungsten and titanium.

39. The method of claim 34, wherein said grating structure occupies approximately 10,000 μ

m² of surface area.

40. The method of claim 34, wherein said grating structure is comprised of approximately 100-700 conductive structures.

41. The method of claim 34, wherein performing scatterometric measurements comprises illuminating said at least one conductive structure and measuring light reflected therefrom.

42. The method of claim 34, wherein said scatterometric measurements are performed on at least a corner region of said conductive structure.

43. The method of claim 34, wherein said scatterometric measurements are performed while said electrical current is being forced through said at least one conductive structure.

44. The method of claim 34, wherein said scatterometric measurements are performed after stopping said electrical current.

45. A method of performing electromigration analysis, comprising:

forming a grating structure above a semiconducting substrate, said grating structure being comprised of a plurality of aluminum conductive structures;

forcing an electrical current through at least one of said conductive structures;

performing scatterometric measurements of said at least one conductive structure to detect a change in shape of at least a portion of said at least one conductive structure; and

determining a susceptibility of said at least one conductive structure to electromigration based upon said detected change in shape of said at least one conductive structure.

46. The method of claim 45, wherein each of said conductive structures is comprised of a conductive metal line and at least one cap layer positioned above and below said conductive metal line.

47. The method of claim 45, wherein each of said conductive structures is comprised of a first metal line and a second metal line that are spaced apart from one another by a conductive contact that is conductively coupled to each of said first and second metal lines.

48. The method of claim 45, wherein said grating structure occupies approximately 10,000 μ

m² of surface area.

49. The method of claim 45, wherein said grating structure is comprised of approximately 100-700 conductive structures.

50. The method of claim 45, wherein performing scatterometric measurements comprises illuminating said at least one conductive structure and measuring light reflected therefrom.

51. The method of claim 45, wherein said scatterometric measurements are performed on at least a corner region of said conductive structure.

52. The method of claim 45, wherein said scatterometric measurements are performed while said electrical current is being forced through said at least one conductive structure.

53. The method of claim 45, wherein said scatterometric measurements are performed after stopping said electrical current.

54. The method of claim 45, further comprising determining a rate of change of said shape of said at least one conductive structure and using said determined rate of change of said shape of said at least one conductive structure to predict the susceptibility of said at least one conductive structure to electromigration.