Feedback control of plasma-enhanced chemical vapor deposition processes

• US 6,913,938 B2
• Filed: 06/18/2002
• Issued: 07/05/2005
• Est. Priority Date: 06/19/2001
• Status: Expired due to Fees

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Iliopoulos, Ilias, Schwarm, Alexander T., Shanmugasundram, Arulkumar P., Parkhomovsky, Alexander, Seamons, Martin J.
• Primary Examiner(s): Smith, Matthew
• Assistant Examiner(s): MALSAWMA, LALRINFAMKIM HMAR
• Application Number:
  US10/174,370
• Publication Number:
  US 20030049390A1
• Time in Patent Office: 1,113 Days
• Field of Search: 438/16, 438/680, 427/9, 427/585, 118/665, 118/697, 700/29, 700/30, 700/31, 700/44, 700/45, 700/108, 700/121, 702/81, 702/82, 702/170, 717/114, 356/237.5, 356/630
• US Class Current: 438/16
• CPC Class Codes: C23C 16/52 Controlling or regulating the coating process C23C16/45557, C23C16/279 take precedence
• CPC Class Codes: G05B 19/00 Programme-control systems
• CPC Class Codes: G05B 19/19 characterised by positioning or contouring control systems, e.g. to control position from one programmed point to another or to control movement along a programmed continuous path
• CPC Class Codes: G05B 19/41865 characterised by job scheduling, process planning, material flow
• CPC Class Codes: G05B 2219/32053 Adjust work parameter as function of other cell
• CPC Class Codes: G05B 2219/32065 Synchronise set points of processes
• CPC Class Codes: G05B 2219/45031 Manufacturing semiconductor wafers
• CPC Class Codes: H01L 21/67253 Process monitoring, e.g. flow or thickness monitoring
• CPC Class Codes: H01L 22/20 Sequence of activities consisting of a plurality of measurements, corrections, marking or sorting steps
• CPC Class Codes: Y02P 90/02 Total factory control, e.g. smart factories, flexible manufacturing systems [FMS] or integrated manufacturing systems [IMS]

Abstract

A method of film deposition in a chemical vapor deposition (CVD) process includes (a) providing a model for CVD deposition of a film that defines a plurality of regions on a wafer and identifies one or more film properties for at least two regions of the wafer and at least one deposition model variable that correlates with the one or more film properties; (b) depositing a film onto a wafer using a first deposition recipe comprising at least one deposition recipe parameter that corresponds to the at least one deposition variable; (c) measuring a film property of at least one of the one or more film properties for the deposited film of step (b) for each of the at least two regions of the wafer and determining a film property; (d) calculating an updated deposition model based upon the film property of step (c) and the model of step (a); and (e) calculating an updated deposition recipe based upon the updated model of step (d) to maintain a target film property. The method can be used to provide feedback to a plurality of deposition chambers or to control film properties other than film thickness.

Claims

1. A method of film deposition in a chemical vapor deposition (CVD) process, comprising:

a) providing a model for CVD deposition of a film that defines a plurality of regions on a wafer and identifies one or more film properties for at least two regions of the wafer and at least one deposition model variable that correlates with the one or more film properties;

b) depositing a film onto a wafer using a first deposition recipe comprising at least one deposition recipe parameter that corresponds to the at least one deposition variable;

c) measuring a film property of at least one of said one or more film properties for the deposited film of step (b) for each of the at least two regions of the wafers wherein each of the two regions is a distinct substantially annular region;

(d) calculating an updated deposition model based upon the measured film property of step (c) and the model of step (a); and

(e) calculating an updated deposition recipe based upon the updated model of step (d) to maintain a target film property.

2. The method of claim 1, wherein the CVD deposition process is a plasma CVD process.

3. The method of claim 2, wherein the plasma CVD process is a plasma-enhanced CVD process.

4. The method of claim 1, wherein the film property of step (c) is an average film property.

5. The method of claim 1, wherein the film property comprises film thickness.

6. The method of claim 5, wherein the at least one deposition model variable comprises deposition time.

7. The method of claim 5, wherein the first deposition recipe is based on the model of step (a) to obtain the target wafer thickness profile.

8. The method of claim 5, wherein the film thickness for a region j of a wafer in the i^th chamber in the model of step (a) is determined according to the equation:

Film_thickness_ij=g(x₁,x₂, . . . x_n)·

time_i

where Film_thickness is film thickness of region j of the wafer in chamber i;

x₁,x₂, . . . x_n are recipe parameters or tool state parameters that effect the deposition rate within region j;

g( . . . ) is a function which describes the dependency of x₁,x₂, . . . x_n on the deposition rate of region j; and

time, is the deposition time in the i^th chamber.

9. The method of claim 1, wherein the first deposition recipe is determined empirically.

10. The method of claim 1, wherein the plurality of regions in the model of step (a) comprises annular regions extending outward from a center point on the wafer.

11. The method of claim 1, wherein the model defines deposition of a plurality of films onto a plurality of wafers in a plurality of deposition chambers.

12. The method of claim 11, wherein the model provides for independent control of at least one deposition parameter for one or more of said plurality of deposition chambers.

13. The method of claim 11, wherein the model provides for common control of at least one deposition parameter for at least two of said plurality of deposition chambers.

14. The method of claim 11, wherein the deposition recipe of step (b) in each chamber is the same.

15. The method of claim 11, wherein the deposition recipe of step (b) in each chamber is different.

16. The method of claim 11, wherein the calculating step of step (e) comprises calculating updated deposition recipes for one or more of said plurality of deposition chambers.

17. The method of claim 1, wherein the model provides for the effect of tool idle time of the deposition process.

18. The method of claim 17, wherein the model defines a first deposition time when the idle time is more than a predetermined period and a second deposition time when the idle time is less than the predetermined period.

19. The method of claim 17, wherein idle time dependence of the deposition rate is defined as:

DR_idle=DR<sub>no—

idle</sub>·

(d₁·

tan<sup>−

1</sup>(d₂·

idle_time+d₃)+d₄)

where DR_idle is the deposition rate with the effect of idle time, DR<sub>no—

idle</sub> is the deposition rate when there is no idle time, d₁ and d₄ determines the maximum change in deposition rate which is caused by idle time, d₂ determines the rate at which this change occurs, and d₃ determines at what idle time the change in deposition rate begins to be significant.

20. The method of claim 1, wherein the model evaluates the reliability of a measurement of a film property.

21. The method of claim 20, wherein the model determines when a recent measurement is outside normal operating variation and, if so, marks the data as suspicious, and ignores the data until a trend is determined from subsequent data.

22. The method of claim 1, wherein the model accounts for a tool state of the CVD process.

23. The method of claim 1, wherein the model provides a methodology for describing the effect of film deposition on the film deposition rate of subsequent wafers.

24. The method of claim 1, wherein the step of providing the model comprises:

(f) depositing a film on at least one wafer in a deposition step using a deposition recipe comprising at least one deposition recipe parameter that corresponds to a deposition model variable;

(g) identifying a plurality of regions on the at least one wafer and measuring a film property for each of the at least one wafers at least two of the plurality of regions after the deposition of step (f); and

(h) recording the deposition parameter and measured film property for at least two of the plurality of regions of the at least one wafer on a recordable medium; and

(i) fitting the data to a linear or non-linear curve that establishes a relationship between the film property of a region of the film and the deposition model variable.

25. The method of claim 24, wherein the model constrains a deposition parameter to within predetermined maximum and minimum values.

26. The method of claim 2 or 24, wherein the at least one deposition parameter includes one or more of the parameters selected from the group consisting of ozone flow rate, oxygen flow rate, reactive gas flow rate, carrier gas flow rate, dopant gas flow rate, RF power, chamber pressure and shower head spacing from the wafer.

27. The method of claim 2 or 24, wherein the model for plasma CVD deposition of a film identifies a relationship between a film deposition variable for the wafer and a film property selected from the group consisting of stress, refractive index, dopant concentration, and extinction coefficient.

28. The method of claim 1, wherein updated model is attained by solving the equation:

$\underset{x}{\min }<br><br>f<br><br>\left(y^{\mathrm{sp}},g<br><br>\left(x\right)\right)$

where x is a vector of recipe parameters and other processing parameters corresponding to the deposition recipe;

g(x) is the model for the deposition process, y^sp is a vector of the one or more film properties; and

ƒ

(y^sp, g(x)) is a penalty function to compensate for the deviation between the model predictions g(x) and the desired thicknesses y^sp.

29. The method of claim 1, wherein the CVD deposition process is an in-line process.

30. The method of claim 1, wherein the CVD deposition process is a batch process.

31. A method of determining a model for a film property in a plasma CVD tool, comprising:

(a) depositing a film on at least one wafer in a plasma CVD deposition step using a deposition recipe having at least one deposition recipe parameter that corresponds to a deposition model variable;

(b) identifying a plurality of regions of the at least one wafer and measuring a film property for the at least one wafers for at least two of the plurality of regions after the deposition of step (a), wherein each of the two regions is a distinct, substantially annular region;

(c) recording the deposition parameter and the measured film property for at least two of the plurality of regions for the at least one wafer on a recordable medium; and

(d) fitting the data to a linear or non-linear curve that establishes a relationship between the film property of a region of the wafer and the deposition model.

32. The method of claim 31, wherein the film property of interest is selected from the group consisting of film thickness, stress, refractive index, dopant concentration and extinction coefficient.

33. The method of claim 31, wherein the at least one deposition parameter comprises one or more parameters selected from the group consisting of deposition time, ozone flow rate, oxygen flow rate, reactive gas flow rate, carrier gas flow rate, dopant gas flow rate, RF power, chamber pressure and shower head spacing from the wafer.

34. The method of claim 31, wherein the model constrains a deposition parameter to be within predetermined maximum and minimum values.

35. A plasma chemical vapor deposition (CVD) tool for deposition of a film, comprising:

a plasma CVD) apparatus comprising a chamber, a vacuum system, an RF generator for generating a source plasma, and a gas delivery system;

controlling means capable of controlling an operating parameter of the deposition process; and

a controller operatively coupled to the controlling means, the controller operating the controlling means to adjust the operating parameter of the deposition process as a function of a model for a film property, the model comprising;

a deposition model for plasma CVD deposition of a film that identifies one or more film properties of the film and at least one deposition model variable that correlates with the one or more film properties, wherein the model defines a plurality of regions on a wafer and identifies a deposition variable and a film property for each of at least two regions of the wafer, wherein each of the two regions is a distinct, substantially annular region.

36. The tool of claim 35, wherein the operating parameter comprises a parameter selected from the group consisting of deposition time, ozone flow rate, oxygen flow rate, reactive gas flow rate, carrier gas flow rate, dopant gas flow rate, RF power, chamber pressure and shower head spacing from the wafer.

37. The tool of claim 35, wherein the film property is selected from the group consisting of film thickness, stress, refractive index, dopant concentration, and extinction coefficient.

38. The tool of claim 35, wherein the model defines deposition of a plurality of films onto a plurality of wafers in a plurality of deposition chambers.

39. The tool of claim 38, wherein the model provides for independent control of at least one operating parameter for one or more of said plurality of deposition chambers.

40. The tool of claim 38, wherein model provides for common control of at least one operating parameter for at least two of said plurality of deposition chambers.

41. The tool of claim 38, wherein the deposition recipe of step (b) in each chamber is the same.

42. The tool of claim 38, wherein the deposition recipe of step (b) in each chamber is different.

43. The tool of claim 38, wherein the calculating step of step (e) comprises calculating updated deposition recipes for one or more of the plurality of deposition chambers.

44. The tool of claim 38, wherein the model provides for the effect of tool idle time of the deposition process.

45. The tool of claim 44, wherein the model defines a first deposition time when the idle time is more than a predetermined period and a second deposition time when the idle time is less than the predetermined period.

46. The tool of claim 35, wherein the model evaluates the reliability of a measurement of a film property.

47. The tool of claim 35, wherein the model provides methodology to describe for the effect of film deposition on the film deposition rate of subsequent wafers.

48. A method of film deposition in a plasma chemical vapor deposition (CVD) process, comprising:

a) providing a model for plasma CVD deposition of a film that identifies one or more film properties for the wafer and at least one deposition model variable that correlates with the film property;

b) depositing a film onto a wafer using a first deposition recipe using a deposition recipe comprising at least one deposition parameter that corresponds to at least one deposition variable;

c) measuring, in at least two distinct, substantially annular regions, the film property for at least one of said one or more film properties for the deposited film of step (b) for the wafer;

d) calculating an updated deposition model based upon the measured film property of step (c) and the model of step (a); and

e) calculating an updated deposition recipe based upon the updated model of step (d) to maintain a target film property profile.

49. The method of claim 48, wherein the film property of step (c) is an average film property.

50. The method of claim 48, wherein the plasma CVD process is a plasma-enhanced CVD process.

51. The method of claim 48, wherein the model defines deposition of a plurality of films onto a plurality of wafers in a plurality of deposition chambers.

52. The method of claim 51, wherein the model provides for independent control of at least one deposition parameter for one or more of said plurality of deposition chambers.

53. The method of claim 51, wherein model provides for common control of at least one deposition parameter for at least two of said plurality of deposition chambers.

54. The method of claim 51, wherein the deposition recipe of step (b) in each chamber is the same.

55. The method of claim 51, wherein the deposition recipe of step (b) in each chamber is different.

56. The method of claim 51, wherein the calculating step of step (e) comprises calculating updated deposition recipes for one or more of said plurality of deposition chambers.

57. The method of claim 48, wherein the model provides for the effect of tool idle time of the deposition process.

58. The method of claim 57, wherein the model defines a first deposition time when the idle time is more than a predetermined period and a second deposition time when the idle time is less than the predetermined period.

59. The method of claim 48, wherein the deposition parameter comprises a parameter selected from the group consisting of deposition time, ozone flow rate, oxygen flow rate, reactive gas flow rate, carrier gas flow rate, dopant gas flow rate, RF power, chamber pressure and shower head spacing from the wafer.

60. The method of claim 48, wherein the film property is selected from the group consisting of film thickness, stress, refractive index, dopant concentration, and extinction coefficient.

61. A computer readable medium comprising instructions being executed by a computer, the instructions including a computer-implemented software application of a chemical vapor deposition (CVD) process, the instructions for implementing the process comprising:

(a) receiving data from a CVD tool relating to a deposition parameter and a measured film property for at least two of a plurality of regions for at least one wafer, wherein each of the two regions is a distinct, substantially annular region;

(b) calculating, from the data of step (a), a deposition model, wherein the model is calculated by determining the relationship between the film property of a region of a wafer and the deposition parameter.

62. The medium of claim 61, further comprising:

c) calculating, using the updated model of step (b) and a target output value for the film property, an updated deposition recipe.

63. The medium of claim 61, wherein the data of step (a) further includes one or more deposition parameters selected from the group consisting of deposition time, ozone flow rate, oxygen flow rate, reactive gas flow rate, carrier gas flow rate, dopant gas flow rate, RF power, chamber pressure and shower head spacing from the wafer.

64. The medium of claim 61, wherein the film property is selected from the group consisting of film thickness, stress, refractive index, dopant concentration, and extinction coefficient.

65. The medium of claim 61, wherein the model provides for independent control of at least one deposition parameter for each deposition chamber.

66. The medium of claim 61, wherein the model constrains a deposition parameter to be within predetermined maximum and minimum values.

67. A chemical vapor deposition (CVD) tool for deposition of a film, comprising:

a) modeling means for defining a plurality of regions on a wafer and identifying one or more film properties for at least two of the regions of the wafer;

b) means for depositing a film onto a wafer using a first deposition recipe comprising at least one deposition parameter, wherein the at least one deposition parameter corresponds to a deposition model variable;

c) means for measuring a film property for at least one of said one or more film properties for the deposited film of step (b) for at least two regions of the wafer, wherein each of the two regions is a distinct, substantially annular region;

d) means for calculating an updated model based upon the measured film property of step (c) and the model of step (a); and

e) means for calculating an updated deposition recipe based upon the updated model of step (d) to maintain a target film property.

68. The CVD tool of claim 67, wherein the CVD process is a plasma CVD process.

69. The CVD tool of claim 67, wherein the model defines deposition of a plurality of films onto a plurality of wafers in a plurality of deposition chambers.

70. The CVD tool of claim 69, wherein the model provides for independent control of at least one deposition parameter for at least two of said plurality of deposition chambers.

71. The CVD tool of claim 69, wherein model provides for common control of at least one deposition parameter for at least two of said plurality of deposition chambers.

72. The CVD tool of claim 69, wherein the deposition recipe of step (b) in each chamber is the same.

73. The CVD tool of claim 69, wherein the deposition recipe of step (b) in each chamber is different.

74. The CVD tool of claim 69, wherein the calculating step of step (e) comprises calculating updated deposition recipes for at least two of said plurality of deposition chambers.

75. The CVD tool of claim 69, wherein the model provides for the effect of tool idle time of the deposition process.

76. The CVD tool of claim 75, wherein the model defines a first deposition time when the idle time is more than a predetermined period and a second deposition time when the idle time is less than the predetermined period.

77. method of film deposition in a chemical vapor deposition (CVD) process, comprising:

a) providing a model for CVD deposition of a film that identifies one or more film properties and at least one deposition model variable that correlates with the one or more film properties and that provides for the effect of tool idle time on the deposition process;

b) depositing a film onto a wafer using a first deposition recipe comprising at least one deposition recipe parameter that corresponds to the at least one deposition variable;

c) measuring a film property of at least one of said one or more film properties for the deposited film of step (b);

(d) calculating an updated deposition model based upon the measured film property of step (c) and the model of step (a); and

(e) calculating an updated deposition recipe based upon the updated model of step (d) to maintain a target film property.

78. The method of claim 77, wherein the model defines a first deposition time when the idle time is more than a predetermined period and a second deposition time when the idle time is less than the predetermined period.

79. The method of claim 77, wherein idle time dependence of the deposition rate is defined as:

DR_idle=DR<sub>no—

idle</sub>·

(d₁·

tan<sup>−

1</sup>(d₂·

idle_time+d₃)+d₄)

where DR_idle is the deposition rate with the effect of idle time, DR<sub>no—

idle</sub> is the deposition rate when there is no idle time, d₁ and d₄ determines the maximum change in deposition rate which is caused by idle time, d₂ determines the rate at which this change occurs, and d₃ determines at what idle time the change in deposition rate begins to be significant.

80. A method of film deposition in a chemical vapor deposition (CVD) process, comprising:

a) providing a model for CVD deposition of a film that identifies one or more film properties and at least one deposition model variable that correlates with the one or more film properties and that evaluates the reliability of a measurement of a film property;

b) depositing a film onto a wafer using a first deposition recipe comprising at least one deposition recipe parameter that corresponds to the at least one deposition variable;

c) measuring a film property of at least one of said one or more film properties for the deposited film of step (b);

(d) calculating an updated deposition model based upon the measured film property of step (c) and the model of step (a); and

(e) calculating an updated deposition recipe based upon the updated model of step (d) to maintain a target film property.

81. The method of claim 80, wherein the model determines when a recent measurement is outside normal operating variation and, if so, marks the data as suspicious, and ignores the data until a trend is determined from subsequent data.