Plasma processing apparatus and method

• US 20060037701A1
• Filed: 06/21/2005
• Published: 02/23/2006
• Est. Priority Date: 06/21/2004
• Status: Active Grant

• Current Assignee: Tokyo Electron Limited
• Original Assignee: Tokyo Electron Limited
• Inventors: Koshiishi, Akira, Yano, Daisuke, Hinata, Kunihiko, Kobayashi, Noriyuki, Koshimizu, Chishio, Iwata, Manabu, Yamazawa, Yohei, Matsumoto, Naoki, Saito, Masashi, Sugimoto, Masaru, Ohtani, Ryuji, Kibi, Kazuo
• Granted Patent: US 7,740,737 B2
• Time in Patent Office: Days
• US Class Current: 156/345.440
• CPC Class Codes: H01J 2237/3344 isotropy
• CPC Class Codes: H01J 37/32082 Radio frequency generated discharge H01J37/32357, H01J37/32366, H01J37/32394 and H01J37/32403 take precedence
• CPC Class Codes: H01J 37/32091 the radio frequency energy being capacitively coupled to the plasma
• CPC Class Codes: H01J 37/32174 Circuits specially adapted for controlling the RF discharge
• CPC Class Codes: H01J 37/32348 Dielectric barrier discharge
• CPC Class Codes: H01J 37/3244 Gas supply means
• CPC Class Codes: H01J 37/32541 Shape
• CPC Class Codes: H01J 37/32568 Relative arrangement or disposition of electrodes; moving means
• CPC Class Codes: H01J 37/32642 Focus rings
• CPC Class Codes: H01J 37/32706 Polarising the substrate
• CPC Class Codes: H01J 37/32834 Exhausting
• 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 21/02164 the material being a silicon oxide, e.g. SiO2
• CPC Class Codes: H01L 21/0217 the material being a silicon nitride not containing oxygen, e.g. SixNy or SixByNz H01L21/02126 and H01L21/0214 take precedence
• CPC Class Codes: H01L 21/31116 by dry-etching
• CPC Class Codes: H01L 21/31138 by dry-etching
• CPC Class Codes: H01L 21/31144 using masks
• CPC Class Codes: H01L 21/67069 for drying etching

Abstract

An apparatus includes an upper electrode and a lower electrode for supporting a wafer disposed opposite each other within a process chamber. A first RF power supply configured to apply a first RF power having a relatively higher frequency is connected to the upper electrode. A second RF power supply configured to apply a second RF power having a relatively lower frequency is connected to the lower electrode. A variable DC power supply is connected to the upper electrode. A process gas is supplied into the process chamber while any one of application voltage, application current, and application power from the variable DC power supply to the upper electrode is controlled, to generate plasma of the process gas so as to perform plasma etching.

Claims

1. A plasma processing apparatus comprising:

a process chamber configured to accommodate a target substrate and to be vacuum-exhausted;

a first electrode and a second electrode disposed opposite each other within the process chamber, the second electrode being configured to support the target substrate;

a first RF power application unit configured to apply a first RF power having a relatively higher frequency to the first electrode;

a second RF power application unit configured to apply a second RF power having a relatively lower frequency to the second electrode;

a DC power supply configured to apply a DC voltage to the first electrode;

a process gas supply unit configured to supply a process gas into the process chamber; and

a control unit configured to control any one of application voltage, application current, and application power from the DC power supply to the first electrode.

2. The plasma processing apparatus according to claim 1, wherein the DC power supply is configured such that any one of application voltage, application current, and application power to the first electrode is variable.

3. The plasma processing apparatus according to claim 1, wherein the control unit is configured to control whether the DC voltage is to be applied or not, from the DC power supply to the first electrode.

4. The plasma processing apparatus according to claim 1, further comprising a detector configured to detect a generated plasma state, wherein the control unit controls any one of application voltage, application current, and application power from the DC power supply to the first electrode, based on information from the detector.

5. The plasma processing apparatus according to claim 1, wherein the first electrode is an upper electrode, and the second electrode is a lower electrode.

6. The plasma processing apparatus according to claim 5, wherein the first RF power applied to the first electrode has a frequency of 13.56 MHz or more.

7. The plasma processing apparatus according to claim 6, wherein the first RF power applied to the first electrode has a frequency of 40 MHz or more.

8. The plasma processing apparatus according to claim 5, wherein the second RF power applied to the second electrode has a frequency of 13.56 MHz or less.

9. The plasma processing apparatus according to claim 1, wherein the DC power supply is configured to apply a voltage within a range of −

2,000 to +1,000V.

10. The plasma processing apparatus according to claim 1, wherein the DC voltage applied from the DC power supply has an absolute value of 500V or more.

11. The plasma processing apparatus according to claim 1, wherein the DC voltage is a negative voltage having an absolute value larger than that of a self-bias voltage generated on a surface of the first electrode by the first RF power applied to the first electrode.

12. The plasma processing apparatus according to claim 1, wherein a surface of the first electrode facing the second electrode is made of a silicon-containing substance.

13. The plasma processing apparatus according to claim 1, wherein a conductive member regularly grounded is disposed within the process chamber to release through plasma a current caused by the DC voltage applied from the DC power supply to the first electrode.

14. The plasma processing apparatus according to claim 13, wherein the first electrode is an upper electrode, the second electrode is a lower electrode, and the conductive member is disposed around the second electrode.

15. The plasma processing apparatus according to claim 13, wherein the first electrode is an upper electrode, the second electrode is a lower electrode, and the conductive member is disposed near the first electrode.

16. The plasma processing apparatus according to claim 15, wherein the conductive member is disposed to form a ring shape around the first electrode.

17. The plasma processing apparatus according to claim 13, wherein the conductive member has a recess to prevent flying substances from being deposited during a plasma process.

18. The plasma processing apparatus according to claim 13, wherein a cover plate is disposed to partly cover the conductive member, and the cover plate is moved relative to the conductive member by a driving mechanism to change a portion of the conductive member to be exposed to plasma.

19. The plasma processing apparatus according to claim 13, wherein the conductive member is columnar and partly exposed to plasma, and the conductive member is rotated about a center thereof by a driving mechanism to change a portion of the conductive member to be exposed to plasma.

20. The plasma processing apparatus according to claim 13, wherein a cover film having a stepped shape and made of a material to be etched by plasma is disposed to partly cover the conductive member, and the cover film is configured to be etched to change a portion of the conductive member to be exposed to plasma.

21. The plasma processing apparatus according to claim 1, wherein a conductive member to be grounded based on a command from an overall control unit is disposed within the process chamber to release through plasma a current caused by the DC voltage applied from the DC power supply to the first electrode.

22. The plasma processing apparatus according to claim 21, wherein the first electrode is an upper electrode, the second electrode is a lower electrode, and the conductive member is disposed around the second electrode.

23. The plasma processing apparatus according to claim 21, wherein the first electrode is an upper electrode, the second electrode is a lower electrode, and the conductive member is disposed near the first electrode.

24. The plasma processing apparatus according to claim 23, wherein the conductive member is disposed to form a ring shape around the first electrode.

25. The plasma processing apparatus according to claim 21, wherein the conductive member has a recess to prevent flying substances from being deposited during a plasma process.

26. The plasma processing apparatus according to claim 21, wherein the conductive member is grounded during plasma etching.

27. The plasma processing apparatus according to claim 21, wherein the conductive member is configured to be supplied with a DC voltage or AC voltage, and the DC voltage or AC voltage is applied based on a command from an overall control unit to sputter or etch a surface of the conductive member.

28. The plasma processing apparatus according to claim 27, wherein the DC voltage or AC voltage is applied to the conductive member during cleaning.

29. The plasma processing apparatus according to claim 27, further comprising a switching mechanism configured to switch connection of the conductive member between the DC power supply and a ground line, wherein, when the conductive member is connected to the DC power supply by the switching mechanism, the DC voltage or AC voltage is applied from the DC power supply to the conductive member to sputter or etch a surface thereof.

30. The plasma processing apparatus according to claim 27, wherein the conductive member is configured to be supplied with a negative DC voltage.

31. The plasma processing apparatus according to claim 30, wherein a grounded conductive auxiliary member is disposed within the process chamber to release a DC electron current flowing into the process chamber when the negative DC voltage is applied to the conductive member.

32. The plasma processing apparatus according to claim 31, wherein the first electrode is an upper electrode, the second electrode is a lower electrode, the conductive member is disposed near the first electrode, and the conductive auxiliary member is disposed around the second electrode.

33. The plasma processing apparatus according to claim 1, further comprising a conductive member disposed within the process chamber and configured to take on either one of a first state and a second state based on a command from an overall control unit, the first state being arranged to ground the conductive member to release through plasma a DC current applied from the DC power supply to the first electrode, and the second state being arranged to apply a DC voltage from the DC power supply to the conductive member to sputter or etch a surface thereof;

and a connection switching mechanism disposed to switch between first connection and second connection to form the first state and the second state, respectively, the first connection being arranged to connect a negative terminal of the DC power supply to the first electrode and to connect the conductive member to a ground line, and the second connection being arranged to connect a positive terminal of the DC power supply to the first electrode and to connect the negative terminal of the DC power supply to the conductive member.

34. The plasma processing apparatus according to claim 33, wherein the first state is formed during plasma etching, and the second state is formed during cleaning of the conductive member.

35. A plasma processing apparatus comprising:

a process chamber configured to accommodate a target substrate and to be vacuum-exhausted;

a first electrode and a second electrode disposed opposite each other within the process chamber, the second electrode being configured to support the target substrate;

a first RF power application unit configured to apply a first RF power having a relatively higher frequency to the first electrode;

a second RF power application unit configured to apply a second RF power having a relatively lower frequency to the second electrode;

a DC power supply configured to apply a DC voltage to the first electrode;

a process gas supply unit configured to supply a process gas into the process chamber; and

a control unit configured to control any one of application voltage, application current, and application power from the DC power supply to the first electrode,

wherein the first electrode includes an inner electrode and an outer electrode, the first RF power is divided and applied to the inner electrode and the outer electrode, and the DC power supply is connected to at least one of the inner electrode and the outer electrode.

36. The plasma processing apparatus according to claim 35, wherein the DC power supply is configured such that DC voltages applied to the inner electrode and the outer electrode are variable independently of each other.

37. The plasma processing apparatus according to claim 36, wherein the inner electrode and the outer electrode are supplied with DC voltages from respective DC power supplies.

38. The plasma processing apparatus according to claim 35, wherein the power supply has one terminal connected to the inner electrode, and another terminal connected to the outer electrode.

39. The plasma processing apparatus according to claim 35, wherein the DC power supply is configured such that any one of application voltage, application current, and application power to the first electrode is variable.

40. The plasma processing apparatus according to claim 35, wherein the control unit is configured to control whether the DC voltage is to be applied or not, from the DC power supply to the first electrode.

41. The plasma processing apparatus according to claim 35, further comprising a detector configured to detect a generated plasma state, wherein the control unit controls any one of application voltage, application current, and application power from the DC power supply to the first electrode, based on information from the detector.

42. The plasma processing apparatus according to claim 35, wherein the first electrode is an upper electrode, and the second electrode is a lower electrode.

43. The plasma processing apparatus according to claim 42, wherein the first RF power applied to the first electrode has a frequency of 13.56 MHz or more.

44. The plasma processing apparatus according to claim 43, wherein the first RF power applied to the first electrode has a frequency of 40 MHz or more.

45. The plasma processing apparatus according to claim 42, wherein the second RF power applied to the second electrode has a frequency of 13.56 MHz or less.

46. The plasma processing apparatus according to claim 35, wherein the DC power supply is configured to apply a voltage within a range of −

2,000 to +1,000V.

47. The plasma processing apparatus according to claim 35, wherein the DC voltage applied from the DC power supply has an absolute value of 500V or more.

48. The plasma processing apparatus according to claim 35, wherein the DC voltage is a negative voltage having an absolute value larger than that of a self-bias voltage generated on a surface of the first electrode by the first RF power applied to the first electrode.

49. The plasma processing apparatus according to claim 35, wherein a surface of the first electrode facing the second electrode is made of a silicon-containing substance.

50. The plasma processing apparatus according to claim 35, wherein a conductive member regularly grounded is disposed within the process chamber to release through plasma a current caused by the DC voltage applied from the DC power supply to the first electrode.

51. The plasma processing apparatus according to claim 50, wherein the first electrode is an upper electrode, the second electrode is a lower electrode, and the conductive member is disposed around the second electrode.

52. The plasma processing apparatus according to claim 50, wherein the first electrode is an upper electrode, the second electrode is a lower electrode, and the conductive member is disposed near the first electrode.

53. The plasma processing apparatus according to claim 52, wherein the conductive member is disposed to form a ring shape around the first electrode.

54. The plasma processing apparatus according to claim 50, wherein the conductive member has a recess to prevent flying substances from being deposited during a plasma process.

55. The plasma processing apparatus according to claim 50, wherein a cover plate is disposed to partly cover the conductive member, and the cover plate is moved relative to the conductive member by a driving mechanism to change a portion of the conductive member to be exposed to plasma.

56. The plasma processing apparatus according to claim 50, wherein the conductive member is columnar and partly exposed to plasma, and the conductive member is rotated about a center thereof by a driving mechanism to change a portion of the conductive member to be exposed to plasma.

57. The plasma processing apparatus according to claim 50, wherein a cover film having a stepped shape and made of a material to be etched by plasma is disposed to partly cover the conductive member, and the cover film is configured to be etched to change a portion of the conductive member to be exposed to plasma.

58. The plasma processing apparatus according to claim 35, wherein a conductive member to be grounded based on a command from an overall control unit is disposed within the process chamber to release through plasma a current caused by the DC voltage applied from the DC power supply to the first electrode.

59. The plasma processing apparatus according to claim 58, wherein the first electrode is an upper electrode, the second electrode is a lower electrode, and the conductive member is disposed around the second electrode.

60. The plasma processing apparatus according to claim 58, wherein the first electrode is an upper electrode, the second electrode is a lower electrode, and the conductive member is disposed near the first electrode.

61. The plasma processing apparatus according to claim 60, wherein the conductive member is disposed to form a ring shape around the first electrode.

62. The plasma processing apparatus according to claim 58, wherein the conductive member has a recess to prevent flying substances from being deposited during a plasma process.

63. The plasma processing apparatus according to claim 58, wherein the conductive member is grounded during plasma etching.

64. The plasma processing apparatus according to claim 58, wherein the conductive member is configured to be supplied with a DC voltage or AC voltage, and the DC voltage or AC voltage is applied based on a command from an overall control unit to sputter or etch a surface of the conductive member.

65. The plasma processing apparatus according to claim 64, wherein the DC voltage or AC voltage is applied to the conductive member during cleaning.

66. The plasma processing apparatus according to claim 64, further comprising a switching mechanism configured to switch connection of the conductive member between the DC power supply and a ground line, wherein, when the conductive member is connected to the DC power supply by the switching mechanism, the DC voltage or AC voltage is applied from the DC power supply to the conductive member to sputter or etch a surface thereof.

67. The plasma processing apparatus according to claim 64, wherein the conductive member is configured to be supplied with a negative DC voltage.

68. The plasma processing apparatus according to claim 67, wherein a grounded conductive auxiliary member is disposed within the process chamber to release a DC electron current flowing into the process chamber when the negative DC voltage is applied to the conductive member.

69. The plasma processing apparatus according to claim 68, wherein the first electrode is an upper electrode, the second electrode is a lower electrode, the conductive member is disposed near the first electrode, and the conductive auxiliary member is disposed around the second electrode.

70. The plasma processing apparatus according to claim 35, further comprising a conductive member disposed within the process chamber and configured to take on either one of a first state and a second state based on a command from an overall control unit, the first state being arranged to ground the conductive member to release through plasma a DC current applied from the DC power supply to the first electrode, and the second state being arranged to apply a DC voltage from the DC power supply to the conductive member to sputter or etch a surface thereof;

and a connection switching mechanism disposed to switch between first connection and second connection to form the first state and the second state, respectively, the first connection being arranged to connect a negative terminal of the DC power supply to the first electrode and to connect the conductive member to a ground line, and the second connection being arranged to connect a positive terminal of the DC power supply to the first electrode and to connect the negative terminal of the DC power supply to the conductive member.

71. The plasma processing apparatus according to claim 70, wherein the first state is formed during plasma etching, and the second state is formed during cleaning of the conductive member.

72. A plasma processing method using a process chamber with a first electrode and a second electrode disposed opposite each other therein, the second electrode being configured to support a target substrate, the method comprising

supplying a process gas into the process chamber, while applying a first RF power having a relatively higher frequency to the first electrode, and applying a second RF power having a relatively lower frequency to the second electrode, to generate plasma of the process gas, thereby performing a plasma process on a target substrate supported by the second electrode,

wherein the method comprises:

applying a DC voltage to the first electrode; and

performing the plasma process on the target substrate while the applying the DC voltage to the first electrode.

73. The plasma processing method according to claim 72, wherein the first electrode is an upper electrode, and the second electrode is a lower electrode.

74. The plasma processing method according to claim 72, wherein the DC voltage is a negative voltage having an absolute value larger than that of a self-bias voltage generated on a surface of the first electrode by the first RF power applied to the first electrode.

75. The plasma processing method according to claim 72, wherein the first RF power applied to the first electrode has a frequency of 13.56 to 60 MHz, and the second RF power applied to the second electrode has a frequency of 300 kHz to 13.56 MHz.

76. The plasma processing method according to claim 72, wherein the process gas is a gas containing fluorocarbon.

77. The plasma processing method according to claim 76, wherein the gas containing fluorocarbon contains at least C₄F₈.

78. The plasma processing method according to claim 77, wherein the gas containing fluorocarbon further contains an inactive gas.

79. The plasma processing method according to claim 72, comprising etching an insulating film on the target substrate supported by the second electrode, wherein the insulating film is an organic insulating film.

80. The plasma processing method according to claim 79, wherein the organic insulating film is an SiOC family film.

81. The plasma processing method according to claim 80, wherein an underlying film made of silicon carbide (SiC) is disposed under the SiOC family film.

82. The plasma processing method according to claim 72, wherein the DC voltage has an absolute value of 1,500V or less.

83. The plasma processing method according to claim 72, wherein a process pressure is set at 1.3 to 26.7 Pa.

84. The plasma processing method according to claim 72, wherein the first RF power applied to the first electrode is set at 3,000 W or less.

85. The plasma processing method according to claim 72, wherein the second RF power applied to the second electrode is set at 100 to 5,000 W.

86. The plasma processing method according to claim 72, comprising etching an insulating film on the target substrate supported by the second electrode, wherein the process gas is a mixture gas of C₄F₈, N₂, and Ar, with a flow-rate ratio of C₄F₈/N₂/Ar=[4 to 20]/[100 to 500]/[500 to 1,500] mL/min.

87. The plasma processing method according to claim 72, comprising etching an insulating film on the target substrate supported by the second electrode, in an over etching step.

88. The plasma processing method according to claim 72, comprising etching an insulating film on the target substrate supported by the second electrode, wherein the process gas comprises a combination of C₅F₈, Ar, and N₂ to increase selectivity of the insulating film relative to an underlying film.

89. The plasma processing method according to claim 72, comprising etching an insulating film on the target substrate supported by the second electrode, wherein the process gas comprises CF₄ or a combination of C₄F₈, CF₄, Ar, N₂, and O₂ to increase selectivity of the insulating film relative to a mask.

90. The plasma processing method according to claim 72, comprising etching an insulating film on the target substrate supported by the second electrode, wherein the process gas comprises any one of a combination of C₄F₆, CF₄, Ar, and O₂, a combination of C₄F₆, C₃F₈, Ar, and O₂, and a combination of C₄F₆, CH₂F₂, Ar, and O₂ to increase an etching rate of the insulating film.

95. A computer storage medium storing a control program for execution on a computer, wherein the control program, when executed, controls a plasma processing apparatus to perform the plasma processing method according to claim 72.

91. A plasma processing method using a process chamber with a first electrode and a second electrode disposed opposite each other therein, the first electrode including an inner electrode and an outer electrode, and the second electrode being configured to support a target substrate, the method comprising

supplying a process gas into the process chamber, while applying a first RF power having a relatively higher frequency to the first electrode, and applying a second RF power having a relatively lower frequency to the second electrode, to generate plasma of the process gas, thereby performing a plasma process on a target substrate supported by the second electrode,

wherein the method comprises:

applying a DC voltage to at least one of the inner electrode and the outer electrode; and

performing the plasma process on the target substrate while the applying the DC voltage to the first electrode.

92. The plasma processing method according to claim 91, comprising etching an insulating film on the target substrate supported by the second electrode, wherein the process gas comprises a combination of C₅F₈, Ar, and N₂ to increase selectivity of the insulating film relative to an underlying film.

93. The plasma processing method according to claim 91, comprising etching an insulating film on the target substrate supported by the second electrode, wherein the process gas comprises CF₄ or a combination of C₄F₈, CF₄, Ar, N₂, and O₂ to increase selectivity of the insulating film relative to a mask.

94. The plasma processing method according to claim 91, comprising etching an insulating film on the target substrate supported by the second electrode, wherein the process gas comprises any one of a combination of C₄F₆, CF₄, Ar, and O₂, a combination of C₄F₆, C₃F₈, Ar, and O₂ and a combination of C₄F₆, CH₂F₂, Ar, and O₂ to increase an etching rate of the insulating film.

96. A computer storage medium storing a control program for execution on a computer, wherein the control program, when executed, controls a plasma processing apparatus to perform the plasma processing method according to claim 91.