Slurry for use with fixed-abrasive polishing pads in polishing semiconductor device conductive structures that include copper and tungsten and polishing methods

• US 6,602,117 B1
• Filed: 08/30/2000
• Issued: 08/05/2003
• Est. Priority Date: 08/30/2000
• Status: Expired due to Fees

• Current Assignee: Micron Technology, Inc.
• Original Assignee: Micron Technology, Inc.
• Inventors: Sinha, Nishant, Chopra, Dinesh
• Primary Examiner(s): Eley, Timothy V.
• Application Number:
  US09/651,808
• Time in Patent Office: 1,070 Days
• Field of Search: 513/07, 513/08, 513/09, 512/93, 216/88, 216/89, 438/692, 438/693, 451/36, 451/41, 451/54, 451/59, 451/60, 451/63, 451/64, 451/65, 451/285, 451/286, 451/287, 451/288, 451/289, 451/290, 451/446, 106/3, 252/79.1
• US Class Current: 451/65
• CPC Class Codes: B24B 37/0056 taking regard of the pH-value of lapping agents
• CPC Class Codes: B24B 37/04 designed for working plane surfaces
• CPC Class Codes: H01L 21/3212 by chemical mechanical polishing [CMP]

Abstract

A method for substantially simultaneously polishing a copper conductive structure of a semiconductor device structure and an adjacent barrier layer. The method includes use of a fixed-abrasive type polishing pad with a substantially abrasive-free slurry in which copper is removed at a rate that is substantially the same as or faster than a rate at which a material, such as tungsten, of the barrier layer is removed. The slurry is formulated so as to oxidize copper at substantially the same rate as or at a faster rate than a material of the barrier layer is oxidized. Thus, copper and the barrier layer material have substantially the same oxidation energies in the slurry or the oxidation energy of the barrier layer material in the slurry may be greater than that of copper. Systems for substantially polishing copper conductive structures and adjacent barrier structures on semiconductor device structures are also disclosed.

Claims

1. A system for polishing a conductive structure of a semiconductor device, the conductive structure including a conductive region comprising copper and an adjacent barrier layer, said system comprising:

a fixed-abrasive polishing pad; and

a slurry to be used with said fixed-abrasive polishing pad, said slurry being substantially free of abrasives and formulated to substantially concurrently polish the conductive region and the barrier layer so as to remove a material of said barrier layer at substantially the same rate as or at a slower rate than copper is removed.

2. The system of claim 1, wherein said fixed-abrasive polishing pad includes abrasive particles comprising at least one of aluminum oxide, titanium dioxide, silicon dioxide, and cerium dioxide.

3. The system of claim 1, wherein said slurry is formulated to oxidize the copper of the conductive region of the conductive structure at substantially the same rate as or at a faster rate than said material of the barrier layer of the conductive structure is oxidized.

4. The system of claim 1, wherein said slurry is formulated to oxidize copper at substantially the same rate as or at a faster rate than tungsten is oxidized.

5. The system of claim 1, wherein, in said slurry, said material of the barrier layer of the conductive structure and copper have substantially the same oxidation energies.

6. The system of claim 5, wherein, in said slurry, said material of the barrier layer of the conductive structure has an oxidation energy of about 0.25 V more to about 0.20 V less than an oxidation energy of copper in said slurry.

7. The system of claim 1, wherein, in said slurry, tungsten has an oxidation energy of about 0.25 V more to about 0.20 V less than an oxidation energy of copper in said slurry.

8. The system of claim 1, wherein, in said slurry, a rate of removal of said material of the barrier layer is up to about ten times slower than a rate of removal of copper.

9. The system of claim 1, wherein, in said slurry, a rate of removal of said material of the barrier layer is about two to about four times slower than a rate of removal of copper.

10. The system of claim 1, wherein said slurry is formulated to remove copper and tungsten without substantially dissolving tungsten that underlies remaining portions of the copper.

11. The system of claim 1, wherein said slurry is formulated to remove copper and said material of the barrier layer without substantially dissolving said material in portions of the barrier layer that underlie remaining portions of the copper.

12. The system of claim 1, wherein said slurry comprises at least one oxidizer, at least pH control agent, and at least one inhibitor.

13. The system of claim 12, wherein said at least one oxidizer comprises at least one of an ammonium compound, a nitrate compound, and an amine compound.

14. The system of claim 12, wherein said at least one oxidizer comprises at least one of hydrogen peroxide, potassium iodate, potassium permanganate, ammonium persulfate, ammonium molybdate, ferric nitrate, nitric acid, potassium nitrate, and ammonia.

15. The system of claim 12, wherein said at least one oxidizer comprises about 0.1% to about 20% of the weight of said slurry.

16. The system of claim 12, wherein said at least one oxidizer comprises about 0.1% to about 5% of the weight of said slurry.

17. The system of claim 12, wherein said at least one pH control agent comprises at least one of potassium hydrogen phthalate, ammonium acetate, ammonium oxalate, ammonium carbamate, ammonium phosphate, ammonium hydrogen phosphate, ammonium dihydrogen phosphate, dibasic ammonium citrate, tribasic ammonium citrate, acetic acid, phosphoric acid, and sulfiric acid.

18. The system of claim 12, wherein said at least one inhibitor comprises at least one of an azole, an amine, and a ring compound.

19. The system of claim 12, wherein said at least one inhibitor comprises at least one of benzenetriazole (BTA), mercaptobenzothiazole, tolytriazole, methylamine, diethylamine, pyridine, quinoline, dicyclohexamine nitrate, potassium silicate, ammonium borate, ammonium phosphate, and potassium dichromate.

20. The system of claim 12, wherein said at least one inhibitor comprises about 0.05% to about 2% of the weight of said slurry.

21. The system of claim 12, wherein said at least one inhibitor comprises about 0.05 to about 0.2% of the weight of said slurry.

22. The system of claim 12, wherein said slurry further comprises at least one complexing agent comprising at least one of glycine, ammonium citrate, ammonium phosphate, and ammonium acetate.

23. The system of claim 22, wherein said at least one complexing agent comprises about 2% to about 15% of the weight of said slurry.

24. The system of claim 22, wherein said at least one complexing agent comprises about 3% to about 5% of the weight of said slurry.

25. The system of claim 12, wherein said slurry includes:

about 0.1% to 20% of said at least one oxidizer, by weight of said slurry; and

about 0.05% to about 2% of said at least one inhibitor, by weight of said slurry.

26. The system of claim 12, wherein said slurry includes:

about 0.1% to about 5% of said at least one oxidizer, by weight of said slurry; and

about 0.05% to about 0.2% of said at least one inhibitor, by weight of said slurry.

27. The system of claim 1, wherein said slurry has a pH of about 2 to about 6.

28. The system of claim 1, wherein said slurry has a pH of about 3 to about 5.

29. The system of claim 1, wherein said fixed-abrasive polishing pad comprises one of a round polishing pad, a belt format polishing pad, and a web format polishing pad.

30. The system of claim 1, wherein said fixed-abrasive polishing pad is configured to be moved incrementally following use thereof to polish a semiconductor device structure.

31. The system of claim 30, wherein said fixed-abrasive polishing pad is configured to be laterally moved in increments that are equal to about 1% or less of a distance across a semiconductor device structure to be polished therewith.

32. The system of claim 1, wherein said slurry removes copper at a temperature of about 27°

C. or cooler.

33. A slurry for use in chemical-mechanical polishing processes, comprising at least one oxidizer, at least one pH control agent, and at least one inhibitor, said slurry being formulated with relative amounts of said at least one oxidizer, said at least one pH control agent, and said at least one inhibitor balanced so as to facilitate substantially concurrent polishing of a first structure comprising copper and a second structure comprising tungsten with said tungsten being removed at substantially the same rate as or at a slower rate than said copper is removed.

34. The slurry of claim 33, being substantially free of abrasives.

35. The slurry of claim 33, wherein said relative amounts are balanced so that said tungsten is oxidized at substantially the same rate as or at a slower rate than said copper is oxidized.

36. The slurry of claim 33, wherein said relative amounts are balanced so that an oxidation energy of tungsten in said slurry is substantially the same as an oxidation energy of copper in said slurry.

37. The slurry of claim 36, wherein said relative amounts are balanced so that an oxidization energy of tungsten in said slurry is about 0.25 V more to about 0.20 V less than an oxidization energy of copper in said slurry.

38. The slurry of claim 36, wherein said relative amounts are balanced so that a rate of removal of tungsten by said slurry is up to about ten times slower than a rate of removal of copper by said slurry.

39. The slurry of claim 36, wherein said relative amounts are balanced so that a rate of removal of tungsten by said slurry is about two to about four times less than a rate of removal of copper by said slurry.

40. The slurry of claim 33, wherein said relative amounts are balanced so that said second structure is not dissolved at a substantially greater rate than said first structure is dissolved.

41. The slurry of claim 33, wherein said at least one pH control agent comprises at least one of potassium hydrogen phthalate, ammonium acetate, ammonium oxalate, ammonium carbamate, ammonium phosphate, ammonium hydrogen phosphate, ammonium dihydrogen phosphate, dibasic ammonium citrate, tribasic ammonium citrate, acetic acid, phosphoric acid, and sulfuric acid.

42. The slurry of claim 33, having a pH of about 2 to about 6.

43. The slurry of claim 33, having a pH of about 3 to about 5.

44. The slurry of claim 33, wherein said at least one oxidizer comprises at least one of an ammonium compound, a nitrate compound, and an amine compound.

45. The slurry of claim 33, wherein said at least one oxidizer comprises at least one of hydrogen peroxide, potassium iodate, potassium permanganate, ammonium persulfate, ammonium molybdate, ferric nitrate, nitric acid, potassium nitrate, ammonia, and other amine compounds.

46. The slurry of claim 33, wherein said at least one inhibitor comprises at least one of an azole, an amine, and a ring compound.

47. The slurry of claim 33, wherein said at least one inhibitor comprises at least one of benzenetriazole (BTA), mercaptobenzothiazole, tolytriazole, methylamine, diethylamine, pyridine, quinoline, dicyclohexamine nitrate, potassium silicate, ammonium borate, ammonium phosphate, and potassium dichromate.

48. The slurry of claim 33, comprising about 0.1% to about 20% of said at least one oxidizer, by weight of said slurry.

49. The slurry of claim 48, comprising about 0.1% to about 5% of said at least one oxidizer, by weight of said slurry.

50. The slurry of claim 33, comprising about 0.05% to about 2% of said at least one inhibitor, by weight of said slurry.

51. The slurry of claim 50, comprising about 0.05% to about 2% of said at least one inhibitor, by weight of said slurry.

52. The slurry of claim 33, further comprising at least one complexing agent.

53. The slurry of claim 52, wherein said at least one complexing agent comprises at least one of glycine, ammonium citrate, ammonium phosphate, and ammonium acetate.

54. The slurry of claim 52, comprising about 1% to about 15% of said at least one complexing agent, by weight of said slurry.

55. The slurry of claim 54, comprising about 3% to about 5% of said at least one complexing agent, by weight of said slurry.

56. The slurry of claim 33, further comprising at least one surfactant.

57. The slurry of claim 56, wherein said at least one surfactant comprises at least one of polyethylene glycol, polyoxyethylene ether, glycerol, polypropylene glycol, polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, and polyoxyethylene oleyl ether.

58. The slurry of claim 56, comprising about 1% to about 15% of said a least one surfactant, by weight of said slurry.

59. The slurry of claim 56, comprising about 1% to about 2% of said at least one surfactant, by weight of said slurry.

60. The slurry of claim 33, comprising a viscosity of about 10 to about 20 cps. at ambient temperature.

61. The slurry of claim 33, further comprising a thickener.

62. A method for formulating a slurry to be used with a fixed-abrasive polishing pad, comprising:

selecting at least one oxidizer, at least one pH control agent, and at least one inhibitor; and

determining concentrations of said at least one oxidizer, said at least one pH control agent, and said at least one inhibitor that form a slurry in which oxidation energies of copper and tungsten will be substantially the same.

63. The method of claim 62, wherein said determining said concentrations comprises determining concentrations of said at least one oxidizer, said at least one pH control agent, and said at least one inhibitor at which an oxidation energy of tungsten is about 0.25 V more to about 0.20 V less than an oxidation energy of copper.

64. The method of claim 62, wherein said determining said concentrations comprises determining concentrations of said at least one oxidizer, said at least one pH control agent, and said at least one inhibitor at which a rate of removal of tungsten is up to about ten times slower than a rate of removal of copper.

65. The method of claim 62, wherein said determining concentrations comprises determining concentrations of said at least one oxidizer, said at least one pH control agent, and said at least one inhibitor at which a rate of removal of tungsten is about two to about four times slower than a rate of removal of copper.

66. The method of claim 62, wherein said selecting said at least one oxider, said at least one pH control agent, and said at least one inhibitor is at least partially related to a type of abrasive of the fixed-abrasive polishing pad.

67. The method of claim 62, wherein said determining said concentrations comprises determining a concentration of said at least one oxidizer within a range of about 0.1% to about 20% of the weight of said slurry.

68. The method of claim 62, wherein said determining said concentrations comprises determining a concentration of said at least one oxidizer within a range of about 0.1% to about 5% of the weight of said slurry.

69. The method of claim 62, wherein said determining said concentrations comprises determining a concentration of said at least one inhibitor to be within a range of about 0.05% to about 2% of the weight of said slurry.

70. The method of claim 62, wherein said determining said concentrations comprises determining a concentration of said at least one inhibitor within a range of about 0.05%to about 0.2% of the weight of said slurry.

71. The method of claim 62, wherein said determining said concentrations comprises:

determining a concentration of said at least one oxidizer within a range of about 0.1% to about 20% of the weight of said slurry; and

determining a concentration of said at least one inhibitor within a range of about 0.05% to about 2% of the weight of said slurry.

72. The method of claim 71, wherein said determining said concentration of said at least one oxidizer comprises determining said concentration within a range of about 0.1% to about 5% of the weight of said slurry.

73. The method of claim 71, wherein said determining said concentration of said at least one inhibitor comprises determining said concentration of said at least one inhibitor within a range of about 0.05% to about 0.2% of the weight of said slurry.

74. The method of claim 62, wherein said determining said concentrations comprises determining at least one set of concentrations at which the slurry will oxidize copper at substantially the same rate as or at a faster rate than tungsten is oxidized.

75. A method for formulating a slurry to be used with a fixed-abrasive polishing pad, comprising:

selecting at least one oxidizer, at least one pH control agent, and at least one inhibitor; and

determining concentrations of said at least one oxidizer, said at least one pH control agent, and said at least one inhibitor that form a slurry which is substantially free of abrasives and in which copper will oxidize at substantially the same rate as or at a faster rate than tungsten is oxidized.

76. A method for formulating a slurry to be used with a fixed-abrasive polishing pad, comprising:

selecting at least one oxidizer, at least one pH control agent, and at least one inhibitor; and

determining concentrations of said at least one oxidizer, said at least one pH control agent, and said at least one inhibitor that form a slurry in which tungsten will be removed at substantially the same rate or a slower rate than copper will be removed.