Inductively coupled plasma reactor with an inductive coil antenna having independent loops

• US 6,016,131 A
• Filed: 05/03/1999
• Issued: 01/18/2000
• Est. Priority Date: 08/16/1995
• Status: Expired due to Term

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Sato, Arthur H., Qian, Xue-Yu
• Primary Examiner(s): Le, Hoanganh
• Assistant Examiner(s): NGUYEN, HOANG V
• Application Number:
  US09/305,091
• Time in Patent Office: 260 Days
• Field of Search: 343/895, 343/866, 343/867, 315/111.51, 315/111.21, 118/723 MP, 118/723 I
• US Class Current: 343/895
• CPC Class Codes: H01J 37/321 the radio frequency energy being inductively coupled to the plasma

Abstract

An inductively coupled plasma reactor for processing a substrate has an inductively coupled coil antenna including plural inductive antenna loops which are electrically separated from one another and independently connected to separately controllable plasma source RF power supplies. The RF power level in each independent antenna loop is separately programmed and instantly changeable to provide a perfectly uniform plasma ion density distribution across the entire substrate surface under a large range of plasma processing conditions, such as different process gases or gas mixtures. In a preferred embodiment, there are as many separately controllable RF power supplies as there are independent antenna loops, and all the separately controllable power supplies receive their RF power from a commonly shared RF generator.

Claims

1. An inductively coupled plasma reactor for processing a substrate in a reactor chamber containing a process gas, comprising:

an inductively coupled coil antenna, said coil antenna comprising plural inductive antenna loops adjacent different portions of said chamber and which are electrically separate from one another;

plural RF impedance match networks each connected to respective ones of the antenna loops;

plural RF power level adjusting circuits each connected to a respective one of the RF match networks and being capable of changing and setting an RF power level;

an RF power distribution controller connected to each of the RF power level adjusting circuits, said controller being capable of simultaneously controlling each of the RF power level adjusting circuits to individually govern the RF power levels to provide a uniform plasma ion density distribution across the top surface of the substrate.

2. The reactor of claim 1 further comprising RF power circuitry connected to said plural inductive antenna loops that generates an RF power signal from a common RF power generator.

3. The reactor of claim 1 further comprising plural RF power generators, each of said RF power generators generating a respective RF power signal.

4. The reactor of claim 3, wherein at least two of said respective RF power signals are a different frequency.

5. The reactor of claim 1 wherein said RF power level adjusting circuits comprises plural variable reactance elements connected in series with respective ones of said independent antenna loops.

6. The reactor of claim 1 wherein said reactor comprises:

a ceiling, wherein said plural independent antenna loops are disposed over said ceiling; and

a wafer pedestal.

7. The reactor of claim 6 wherein said plural independent antenna loops comprise respective conductors wound around respective loop axes, all of said respective loop axes being coincident with an axis of symmetry of said wafer pedestal.

8. The reactor of claim 7 wherein said reactor ceiling is dome-shaped and wherein said axis of symmetry is coincident with an axis of symmetry of said dome-shaped ceiling.

9. The reactor of claim 8 wherein said antenna loops are centered at intervals along plural radii of said dome-shaped ceiling, said plural radii being centered relative to said wafer pedestal.

10. The reactor of claim 9 wherein said intervals are uniform.

11. The reactor of claim 6 wherein said plural independent antenna loops comprise respective conductors wound around respective loop axes, said respective loop axes being distributed among different points over said ceiling, said loops having diameters less than that of said wafer.

12. The reactor of claim 11 wherein said diameters are a relatively small fraction of the diameter of said wafer whereby each loop primarily affects a plasma ion density at a small local region over said wafer.

13. A plasma reactor for processing a substrate in a reactor chamber containing a process gas, comprising:

a coil antenna including plural antenna loops adjacent respective different portions of said chamber, said loops being in parallel with each other electrically, and adapted to establish a plasma within said chamber primarily by inductive coupling;

plural RF impedance match networks each connected to respective ones of the antenna loops;

a plurality of RF power level adjustors connected to respective ones of the RF impedance match network, said RF power level adjustors connected in series with said antenna loops, each of said RF power level adjustors also adapted to be connected to a source of RF power and being independently controllable with respect to the remaining RF power level adjustors to provide a desired plasma characteristic;

an RF power distribution controller wherein each of said RF power level adjustors responds to an adjustment signal from said controller to adjust the power to each antenna loop to achieve a predetermined desired plasma characteristic.

14. A plasma reactor as in claim 13 in which each antenna loop is provided with a respective one of said power level adjustors.

15. A plasma reactor as in claim 13 in which a single source of RF power supplies each of said power level adjustors.

16. A plasma reactor as in claim 13 in which each of said loops has a central axis of symmetry.

17. A plasma reactor as in claim 16 in which each said axis of symmetry is spaced from every other such axis.

18. A plasma reactor as in claim 16 in which at least two of said axes of symmetry coincide with each other.

19. A plasma reactor as in claim 13 in which each of said adjustors includes an adjustable reactance.

20. A method for processing a substrate in a reactor chamber containing a process gas, comprising:

coupling RF power into said chamber using an RF radiator comprising plural conductive elements which are electrically separated from one another and distributed at respective locations adjacent said chamber, each of said plural conductive elements connected to a respective one of a plural RF impedance match network, said coupling of RF power by employing plural RF power level adjusting circuits, each of the adjusting circuits being connected to a respective one of the RF impedance match networks and connected to receive respective RF power signals, respective RF power signals being provided by an RF power generator, each of the RF power level adjusting circuits further being capable of changing and setting an RF power level of the RF power signal; and

simultaneously controlling each of the RF power level adjusting circuits to individually govern the RF power level of each of the RF power signals so as to control the plasma ion density distribution across the top surface of the substrate by employing an RF power distribution controller connected to each of the RF power level adjusting circuits.

21. The method of claim 20, wherein respective RF power signals are generated by plural RF power generators.

22. The method of claim 21, wherein at least two of said plural RF power generators generate different frequencies.

23. A plasma reactor for processing a substrate, comprising:

an RF radiator capable of coupling power into a processing chamber, said radiator comprising plural conductive elements adjacent different portions of the chamber which are electrically separate from one another;

plural RF impedance match networks each connected to respective ones of the plural conductive elements;

plural RF power level adjusting circuits each connected to a respective one of the RF impedance match networks and connected to receive respective RF power signals, each of the RF power level adjusting circuits being capable of changing and setting an RF power level of the RF power signal;

an RF power distribution controller connected to each of the RF power level adjusting circuits, said controller being capable of simultaneously controlling each of the RF power level adjusting circuits to individually govern the RF power level of each of the RF power signals to provide a uniform plasma ion density distribution across the top surface of the substrate.

24. The reactor of claim 23 further comprising:

plural RF power generators providing said respective RF power signals, wherein at least two of said respective RF power signals are different frequencies.

25. An inductively coupled plasma reactor for processing a substrate, comprising:

a wafer pedestal;

an inductively coupled coil antenna, said coil antenna comprising plural inductive antenna loops adjacent different portions of said chamber and which are electrically separate from one another;

said plural inductive antenna loops comprising respective conductors wound around respective loop axes, all of said respective loop axes being coincident with an axis of symmetry of said wafer pedestal;

plural RF impedance match networks each connected to respective ones of the antenna loops;

plural RF power level adjusting circuits each connected to a respective one of the RF impedance match networks and connected to receive respective RF power signals, each of the RF power level adjusting circuits being capable of changing and setting an RF power level of the RF power signal; and

an RF power distribution controller connected to each of the RF power level adjusting circuits, said controller being capable of simultaneously controlling each of the RF power level adjusting circuits to individually govern the RF power level of each of the RF power signals to provide a uniform plasma ion density distribution across the top surface of the substrate.

26. The reactor of claim 25 further comprising RF power circuitry connected to said plural RF power level adjusting circuits, said RF power circuitry generating said respective RF power signals from a common RF generator.

27. The reactor of claim 26 wherein said RF power level adjusting circuits comprise plural variable reactance elements connected in series with respective ones of said independent antenna loops.

28. The reactor of claim 25 further comprising plural RF power generators generating said respective RF power signals.

29. The reactor of claim 28 wherein at least two of said respective RF power signals are of different frequencies.

30. The reactor of claim 25 wherein said reactor further comprises a ceiling, wherein said plural independent antenna loops are disposed over said ceiling.

31. The reactor of claim 30 wherein said reactor ceiling is dome-shaped and wherein said axis of symmetry is coincident with an axis of symmetry of said dome-shaped ceiling.

32. The reactor of claim 25 further comprising RF power circuitry connected to said plural RF power level adjusting circuits, said RF power circuitry generating said respective RF power signal from a common RF generator.

33. The reactor of claim 32 wherein said RF power level adjusting circuits comprise plural variable reactance elements connected in series with respective ones of said independent antenna loops.

34. The reactor of claim 25 further comprising plural RF power generators generating said respective RF power signals.

35. The reactor of claim 34 wherein at least two of said respective RF power signals are of different frequencies.

36. The reactor of claim 25 wherein said reactor further comprises a ceiling, wherein said plural independent antenna loops are disposed over said ceiling.

37. The reactor of claim 36 wherein said ceiling is dome-shaped and wherein said axis of symmetry is coincident with an axis of symmetry of said dome-shaped ceiling.

38. A plasma reactor for processing a workpiece, comprising:

a processing chamber;

a workpiece support disposed within said processing chamber;

a dome-shaped ceiling overlying said workpiece support;

an RF radiator comprising plural conductive elements that are electrically separate from each other, said plural conductive elements adjacent different portions of said processing chamber;

an RF power distribution controller connected to respective ones of said plural conductive elements, said RF power distribution controller capable of simultaneously controlling an RF power level to each one of said plural conductive elements so as to provide a uniform plasma ion density distribution across the workpiece.

39. The reactor of claim 38 further comprising plural RF impedance match networks each connected to respective ones of said plural conductive elements.

40. The reactor of claim 39, further comprising plural RF power level adjusting circuits each connected to said plural RF impedance match networks and to said RF power distribution controller, each of said plural RF power level adjusting circuits capable of changing and setting said RF power level.

41. The reactor of claim 40 wherein each of said plural RF power level adjusting circuits comprises plural variable reactance elements connected in series with respective ones of said plural conductive elements.

42. The reactor of claim 38 further comprising RF power circuitry connected to said plural conductive elements that generates an RF power signal from a common RF power generator.

43. The reactor of claim 38 further comprising plural RF power generators each generating an RF power signal.

44. The reactor of claim 43, wherein at least two of said plural RF power signals are at different frequencies.

45. The reactor of claim 38 wherein said plural conductive elements comprise respective conductors wound around respective axes that are coincident with an axis of symmetry of said workpiece support.

46. The reactor of claim 45, wherein said axis of symmetry is coincident with an axis of symmetry of said dome-shaped ceiling.

47. The reactor of claim 46, wherein each of said plural conductive elements are centered at intervals along plural radii of said dome-shaped ceiling, said plural radii being centered relative to said workpiece support.

48. The reactor of claim 38, wherein said plural conductive elements comprise respective conductors wound around respective axes, said respective axes being distributed among different points over said dome-shaped ceiling, and wherein each of said plural conductive elements have a diameter less than a diameter of said workpiece.

49. The reactor of claim 48, wherein said plural conductive element diameters are a relatively small fraction of said workpiece diameter whereby each one of said plural conductive elements primarily affects a plasma ion density at a small local region over said workpiece.

50. The reactor of claim 49, wherein said intervals are uniform.

51. A method of processing a workpiece, comprising:

coupling RF power into a processing chamber, said processing chamber having a workpiece support therein and a dome-shaped ceiling overlying said workpiece support, using an RF radiator comprising plural conductive elements that are electrically separate from each other and distributed at different locations adjacent said processing chamber, each of said plural conductive elements connected to an RF power distribution controller; and

simultaneously controlling an RF power level to each one of said plural conductive elements using said RF power distribution controller so as to control the plasma ion density distribution across the top surface of the workpiece.

52. The method of claim 51, further comprising plural RF impedance match networks each connected to respective ones of said plural conductive elements.

53. The method of claim 52, further comprising plural RF power level adjusting circuits each connected to said plural RF impedance match networks and to said RF power distribution controller, each of said plural RF power level adjusting circuits capable of changing and setting said RF power level.

54. The method of claim 53, wherein each of said plural RF power level adjusting circuits comprise plural variable reactance elements connected in series with respective ones of said plural conductive elements.

55. The method of claim 51 further comprising RF power circuitry connected to said plural conductive elements that generate an RF power signal from a common RF power generator.

56. The method of claim 51 further comprising plural RF power generators each generating an RF power signal.

57. The method of claim 56, wherein at least two of said plural RF power signals are at different frequencies.

58. The method of claim 51, wherein said plural conductive elements comprise respective conductors wound around respective axes that are coincident with an axis of symmetry of said workpiece support.

59. The method of claim 58, wherein said axis of symmetry is coincident with an axis of symmetry of said dome-shaped ceiling.

60. The method of claim 59, wherein each of said plural conductive elements are centered at intervals along plural radii of said dome-shaped ceiling, said plural radii being centered relative to said workpiece support.

61. The method of claim 51, wherein said plural conductive elements comprise respective conductors wound around respective axes, said respective axes being distributed among different points over said dome-shaped ceiling, and wherein each of said plural conductive elements have a diameter less that a diameter of said workpiece.

62. The method of claim 61, wherein said plural conductive elements diameters are a relatively small fraction of said workpiece diameter whereby each one of said plural conductive elements primarily affects a plasma density at a small local region over said workpiece.

63. The method of claim 62, wherein said intervals are uniform.