Monitoring substrate processing using reflected radiation

• US 6,831,742 B1
• Filed: 10/23/2000
• Issued: 12/14/2004
• Est. Priority Date: 10/23/2000
• Status: Active Grant

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Sui, Zhifeng, Guan, Yu, Noorbakhsh, Hamid, Shan, Hongqing, Johansson, Nils
• Primary Examiner(s): Font, Frank G.
• Assistant Examiner(s): Punnoose, Roy M.
• Application Number:
  US09/695,577
• Time in Patent Office: 1,513 Days
• Field of Search: 356/369, 356/364, 356/630, 250/225, 438/700, 438/701, 438/710, 438/14, 438/16, 216/2
• US Class Current: 356/369
• CPC Class Codes: G01N 21/21 Polarisation-affecting properties G01N21/19 takes precedence
• CPC Class Codes: G01N 21/71 thermally excited
• CPC Class Codes: G01N 21/9501 Semiconductor wafers manufacturing processes per se of semiconductor devices implementing a measuring step H01L22/10
• CPC Class Codes: G01N 21/956 Inspecting patterns on the surface of objects contactless testing of electronic circuits G01R31/308; testing currency G07D; manufacturing processes per se of semiconductor devices implementing a measuring step H01L22/10
• CPC Class Codes: H01J 37/32935 Monitoring and controlling tubes by information coming from the object and/or discharge
• CPC Class Codes: H01L 21/31116 by dry-etching
• CPC Class Codes: H01L 21/31633 Deposition of carbon doped silicon oxide, e.g. SiOC

Abstract

A substrate processing apparatus 27 comprises a chamber 35 capable of processing a substrate 20, a radiation source 58 to provide a radiation, a radiation polarizer 59 adapted to polarize the radiation to one or more polarization angles that are selected in relation to an orientation 33 of a feature 25 being processed on the substrate 20, a radiation detector 54 to detect radiation reflected from the substrate 20 during processing and generate a signal, and a controller 100 to process the signal.

Claims

1. A substrate processing apparatus comprising:

a chamber capable of processing a substrate;

a radiation source to provide a radiation;

a radiation polarizer adapted to polarize the radiation to one or more polarization angles that are selected in relation to an orientation of a feature being processed on the substrate;

a radiation detector to detect radiation reflected from the substrate during processing and generate a signal; and

a controller to process the signal.

2. An apparatus according to claim 1 wherein the radiation is polarized to a plurality of polarization angles.

3. An apparatus according to claim 1 wherein the radiation is polarized to a polarization angle that is substantially parallel, or substantially perpendicular, to the orientation of the feature.

4. An apparatus according to claim 1 wherein the feature comprises a principal orientation, and wherein the radiation is polarized to a first polarization angle substantially parallel to the principal orientation and a second polarization angle substantially perpendicular to the principal orientation.

5. An apparatus according to claim 1 wherein the controller processes the signal to increase the intensity of a signal component arising from the radiation reflected by the feature being processed in the substrate relative to other signal components.

6. An apparatus according to claim 1 wherein the controller processes signal components of reflected radiation that are polarized at different polarization angles.

7. An apparatus according to claim 6 wherein the controller determines a ratio or subtraction product of the reflected radiation signal components.

8. An apparatus according to claim 7 wherein the reflected radiation signal components comprise signal components arising from radiation polarized at polarization angles which are substantially parallel, or substantially perpendicular, to the orientation of the feature.

9. An apparatus according to claim 1 wherein the radiation polarizer comprises one or more polarizing filters.

10. An apparatus according to claim 1 wherein the controller comprises a bandpass filter.

11. An apparatus according to claim 10 wherein the bandpass filter increases the intensity of a signal component arising from the radiation reflected by the feature being processed in the substrate relative to other signal components.

12. An apparatus according to claim 10 wherein the bandpass filter selectively passes through signal frequencies within a frequency passband that is selected in relation to a intensity modulation frequency of radiation reflected from the feature being processed on the substrate.

13. An apparatus according to claim 12 wherein the frequency passband is centered about the modulation frequency.

14. An apparatus according to claim 1 wherein:

the chamber comprises a substrate support, gas supply, gas energizer, and gas exhaust; and

the controller analyzes the signal to detect an attribute in the signal related to a process endpoint, the attribute comprising a valley, peak, upward slope or downward slope, in the signal; and

the controller operates one or more of the substrate support, gas supply, gas energizer, and gas exhaust, to change a process condition upon detection of the signal attribute.

15. A method of processing a substrate in a process zone, the method comprising the steps of:

(a) providing a substrate in the process zone;

(b) setting process conditions to process the substrate with an energized gas;

(c) providing radiation that is polarized at one or more polarization angles that are selected in relation to an orientation of a feature being processed on the substrate;

(d) detecting radiation reflected from the substrate and generating a signal in response to the detected radiation; and

(e) processing the signal.

16. A method according to claim 15 wherein in (c) the radiation is polarized at a plurality of polarization angles.

17. A method according to claim 15 wherein in (c) the one or more polarization angles comprise a polarization angle is substantially parallel, or substantially perpendicular, to the orientation of the feature.

18. A method according to claim 15 wherein in (c) the one or more polarization angles comprise a first polarization angle substantially parallel to the feature orientation and a second polarization angle substantially perpendicular to the feature orientation.

19. A method according to claim 15 wherein the feature is a trench having a principal orientation, and wherein in (c) the one or more polarization angles comprise a polarization angle is related to the principal orientation of the trench.

20. A method according to claim 19 wherein (e) comprises determining a depth of the trench.

21. A method according to claim 15 wherein (e) comprises increasing the intensity of a signal component that arises from the radiation reflected by a feature being processed in the substrate relative to other signal components.

22. A method according to claim 21 comprising processing signal components of reflected radiation that are polarized at different polarization angles.

23. A method according to claim 22 comprising determining a ratio or subtraction product of the reflected radiation signal components.

24. A method according to claim 22 wherein the reflected radiation signal components comprises signal components arising from radiation polarized at polarization angles which are substantially parallel, or substantially perpendicular, to the orientation of the feature.

25. A method according to claim 15 wherein (c) comprises increasing the intensity of a signal component arising from the radiation reflected by the feature being processed in the substrate relative to other signal components.

26. A method according to claim 25 wherein (c) comprising filtering the signal to selectively pass through a frequency passband relating to an intensity modulation frequency of the radiation reflected from the feature being processed on the substrate.

27. A method according to claim 26 wherein the frequency passband is centered about the modulation frequency.

28. A method according to claim 15 wherein (e) comprises analyzing the signal to detect an attribute in the signal related to a process endpoint, the attribute comprising a valley, peak, upward slope, or downward slope, in the signal, and wherein the method further comprises:

changing a process condition upon detection of the signal attribute.

29. A substrate processing apparatus comprising:

a chamber capable of processing a substrate;

a radiation source to provide a radiation;

a radiation polarizer adapted to polarize the radiation to a plurality of polarization angles;

a radiation detector to detect radiation reflected from the substrate during processing and generate a signal; and

a controller to process the signal.

30. An apparatus according to claim 29 wherein the plurality of polarization angles are selected in relation to a principal orientation of a feature being processed on the substrate.

31. An apparatus according to claim 30 wherein the plurality of polarization angles are substantially parallel or substantially perpendicular to the principal orientation.

32. An apparatus according to claim 29 wherein the controller processes signal components of reflected radiation that are polarized at the plurality of polarization angles.

33. An apparatus according to claim 32 wherein the controller determines a ratio or subtraction product of the reflected radiation signal components.

34. An apparatus according to claim 29 wherein the controller comprises a bandpass filter to selectively passes through signal frequencies within a frequency passband that is selected in relation to an intensity modulation frequency of radiation reflected from a feature being processed on the substrate.

35. An apparatus according to claim 34 wherein the frequency passband is centered about the modulation frequency.

36. A method of processing a substrate in a process zone, the method comprising the steps of:

(a) providing a substrate in the process zone;

(b) setting process conditions to process a feature on the substrate with an energized gas;

(c) providing radiation that is polarized to a plurality of polarization angles;

(d) detecting radiation reflected from the substrate and generating a signal in response to the detected radiation; and

(e) processing the signal.

37. A method according to claim 36 wherein in (c) the plurality of polarization angles are selected in relation to an orientation of a feature being processed on the substrate.

38. A method according to claim 37 wherein the plurality of polarization angles comprise a polarization angle that is substantially parallel, or substantially perpendicular, to the feature orientation.

39. A method according to claim 37 wherein plurality of polarization angles comprise a first polarization angle substantially parallel to the feature orientation and a second polarization angle substantially perpendicular to the feature orientation.

40. A method according to claim 36 wherein (e) comprises increasing the intensity of a signal component that arises from the radiation reflected by a feature being processed in the substrate relative to other signal components.

41. A method according to claim 40 comprising processing signal components of the reflected radiation that are polarized to different polarization angles.

42. A method according to claim 41 comprising determining a ratio or subtraction product of the reflected radiation signal components.

43. A method according to claim 42 wherein the reflected radiation signal components comprise signal components arising from radiation polarized at polarization angles which are substantially parallel, or substantially perpendicular, to the orientation of the feature.

44. A method according to claim 36 wherein (e) comprises filtering the signal to selectively pass through a frequency passband relating to an intensity modulation frequency of the radiation reflected from a feature being processed on the substrate.

45. A method according to claim 44 wherein the frequency passband is centered about the modulation frequency.

46. A substrate processing apparatus comprising:

a chamber capable of processing a substrate;

a radiation source to provide a radiation;

a radiation detector to detect radiation reflected from the substrate during processing and generate a signal; and

a bandpass filter to filter the signal.

47. An apparatus according to claim 46 wherein the bandpass filter is adapted to selectively pass through frequencies in a frequency passband while reducing the intensity of other frequencies.

48. An apparatus according to claim 46 wherein the bandpass filter increases the intensity of a signal component arising from the radiation reflected by a feature being processed on the substrate relative to other signal components.

49. An apparatus according to claim 46 wherein the bandpass filter selectively passes through signal frequencies within a frequency passband that is selected in relation to an intensity modulation frequency of radiation reflected from the feature being processed on the substrate.

50. An apparatus according to claim 49 wherein the frequency passband is centered about the modulation frequency.

51. An apparatus according to claim 46 wherein the frequency passband comprises a range of about ±

10% of the modulation frequency.

52. An apparatus according to claim 46 wherein the bandpass filter comprises an electrical signal processor.

53. An apparatus according to claim 52 wherein the electrical signal processor comprises a digital signal processor.

54. An apparatus according to claim 46 comprising a radiation polarizer adapted to polarize the radiation to a plurality of polarization angles.

55. An apparatus according to claim 54 wherein the radiation polarizer comprises one or more polarizing filters.

56. An apparatus according to claim 46 comprising a radiation polarizer to polarize the radiation to a polarization angle that is related to an orientation of a feature being processed on the substrate.

57. An apparatus according to claim 56 comprising a radiation polarizer adapted to polarize the radiation to a polarization angle that is substantially parallel, or substantially perpendicular, to the orientation of the feature.

58. An apparatus according to claim 56 wherein the feature comprises a principal orientation, and wherein the radiation is polarized to a first polarization angle substantially parallel to the principal orientation and a second polarization angle substantially perpendicular to the principal orientation.

59. An apparatus according to claim 46 comprising a controller adapted to process the signal to increase the intensity of a signal component arising from the radiation reflected by the feature being processed on the substrate relative to other signal components.

60. An apparatus according to claim 59 wherein the controller processes signal components of reflected radiation that are polarized at different polarization angles.

61. An apparatus according to claim 59 wherein the controller determines a ratio or subtraction product of the reflected radiation signal components.

62. An apparatus according to claim 61 wherein the reflected radiation signal components comprises signal components arising from radiation polarized at polarization angles which are substantially parallel, or substantially perpendicular, to the orientation of the feature.

63. A substrate processing method comprising:

(a) placing a substrate in a process zone;

(b) setting process conditions of an energized gas to process the substrate;

(c) providing a source of radiation in the process zone;

(d) detecting radiation that is reflected from a substrate during processing of the substrate and generating a signal; and

(e) bandpass filtering the signal.

64. A method according to claim 63 wherein (e) comprises increasing the intensity of a signal component arising from the radiation reflected by a feature being processed on the substrate relative to other signal components.

65. A method according to claim 63 wherein (e) comprises selectively passing through frequencies in a frequency passband while reducing the intensity of other frequencies.

66. A method according to claim 63 wherein the frequency passband relates to an intensity modulation frequency of the radiation reflected from the feature being processed on the substrate.

67. A method according to claim 66 wherein the frequency passband is centered about the modulation frequency.

68. A method according to claim 63 comprising providing radiation polarized at one or more polarization angles that are selected in relation to an orientation of a feature being processed on the substrate.

69. A method according to claim 68 wherein the radiation is polarized at a plurality of polarization angles.

70. A method according to claim 68 wherein the one or more polarization angles comprise a polarization angle is substantially parallel, or substantially perpendicular, to the orientation of the feature.

71. A method according to claim 68 wherein the one or more polarization angles comprise a first polarization angle substantially parallel to the feature orientation and a second polarization angle substantially perpendicular to the feature orientation.

72. A method according to claim 71 wherein the feature is a trench having a principal orientation, and wherein the one or more polarization angles comprise a polarization angle that is related to the principal orientation of the trench.

73. A method according to claim 68 comprising processing signal components of reflected radiation that are polarized at the one or more polarization angles.

74. A method according to claim 73 comprising determining a ratio or subtraction product of the reflected radiation signal components.

75. A method according to claim 73 wherein the reflected radiation signal components comprises signal components arising from radiation polarized at polarization angles which are substantially parallel, or substantially perpendicular, to the orientation of the feature.

76. A substrate processing apparatus comprising:

a process chamber comprising a substrate support, gas inlet, gas energizer, gas exhaust, and a wall having a recess with a window therein and a mask over the window; and

a process monitoring system capable of monitoring a process that may be conducted in the process chamber, through the window in the recess of the wall.

77. An apparatus according to claim 76 wherein the mask covers the window.

78. An apparatus according to claim 76 wherein the mask comprises one or more apertures sized to reduce the deposition of process residues therein.

79. An apparatus according to claim 78 wherein the apertures comprise an aspect ratio of at least about 0.25:

1.

80. An apparatus according to claim 78 wherein the apertures comprise an aspect ratio of less than about 12:

1.

81. An apparatus according to claim 78 wherein the apertures comprise an opening size of from about 0.1 to about 50 mm.

82. An apparatus according to claim 78 wherein the apertures comprise a depth of from about 0.5 to about 500 mm.

83. An apparatus according to claim 76 further comprising an electromagnetic field source adapted to maintain an electromagnetic field about the window.

84. An apparatus according to claim 83 wherein the electromagnetic field source comprises an electrical or magnetic field source.

85. An apparatus according to claim 76 wherein the process monitoring system comprises a radiation detector to detect a reflected radiation and generate a signal, and a filter to filter the signal.

86. An apparatus according to claim 76 further comprising a radiation polarizer.

87. A method of processing a substrate in a chamber, the method comprising:

placing the substrate in the chamber;

providing an energized gas in the chamber to process the substrate;

masking a window provided in a recess in a wall of the chamber; and

monitoring a process that may be conducted in the chamber through the window in the recess in the wall.

88. A method according to claim 87 wherein masking the window comprises reducing deposition of process residues on the window.

89. A method according to claim 87 wherein masking the window comprises covering the window with a mask having one or more apertures.

90. A method according to claim 87 comprising maintaining an electromagnetic field about the window.

91. A method according to claim 90 comprising preferentially localizing the electromagnetic field about the window.

92. A method according to claim 87 comprising detecting a substrate reflected radiation, generating a signal, and a filtering the signal.

93. A method according to claim 92 comprising polarizing a radiation that is reflected from the substrate and detecting the radiation, and processing the signal.

94. A method according to claim 93 comprising polarizing the radiation to one or more polarization angles related to an orientation of a feature being processed on the substrate.

95. A substrate etching method comprising:

(a) placing a substrate in a process zone, the substrate having a first layer with an initial thickness;

(b) providing energized gas in the process zone to etch features in the first layer in the substrate, the features having a principal orientation;

(c) polarizing radiation at one or more of (i) a first polarization angle that is substantially parallel to the principal orientation of the features being etched on the substrate, and (ii) a second polarization angle that is substantially perpendicular to the principal orientation;

(d) directing the polarized radiation onto the substrate;

(e) detecting an intensity of the polarized radiation reflected from the substrate and generating a signal trace; and

(f) evaluating the signal trace to identify a feature of the signal trace that occurs when a predetermined thickness of the first layer remains on the substrate to determine an endpoint of the process.

96. A method according to claim 95 comprising evaluating the signal trace relative to a stored trace or feature.

97. A method according to claim 95 comprising the initial steps of (1) determining a signal trace of an intensity of a reflected radiation from a substrate being etched, and (2) selecting the feature from the signal trace.

98. A substrate etching apparatus comprising:

(a) a chamber comprising a substrate support, gas supply, gas energizer, and gas exhaust;

the chamber capable of maintaining an energized gas therein to etch features in the substrate, the features having a principal orientation;

(b) a radiation polarizer to polarize radiation to one or more of (i) a first polarization angle that is substantially parallel to the principal orientation of the features being etched in the substrate, and (ii) a second polarization angle that is substantially perpendicular to the principal orientation;

(c) a radiation detector to detect an intensity of the polarized radiation reflected from the substrate and generate a signal trace; and

(d) a controller to evaluate the signal trace to identify a feature of the signal trace that occurs when a predetermined thickness of the first layer remains on the substrate to determine an endpoint of the process.

99. An apparatus according to claim 98 wherein the controller evaluates the signal trace relative to a stored trace or feature.