Model-based pattern characterization to generate rules for rule-model-based hybrid optical proximity correction

• US 20060085772A1
• Filed: 09/08/2005
• Published: 04/20/2006
• Est. Priority Date: 10/15/2004
• Status: Active Grant

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Takumi Technology Corporation
• Inventors: Zhang, Youping
• Granted Patent: US 7,627,837 B2
• Time in Patent Office: Days
• US Class Current: 716/52
• CPC Class Codes: G03F 1/36 Masks having proximity correction features; Preparation thereof, e.g. optical proximity correction [OPC] design processes
• CPC Class Codes: G03F 7/70441 Optical proximity correction [OPC]
• CPC Class Codes: G03F 7/705 Modelling or simulating from physical phenomena up to complete wafer processes or whole workflow in wafer productions

Abstract

A system and method are provided for analyzing layout patterns via simulation using a lithography model to characterize the patterns and generate rules to be used in rule-based optical proximity correction (OPC). The system and method analyze a series of layout patterns conforming to a set of design rules by simulation using a lithography model to obtain a partition of the pattern spaces into one portion that requires only rule-based OPC and another portion that requires model-based OPC. A corresponding hybrid OPC system and method are also introduced that utilize the generated rules to correct an integrated circuit (IC) design layout which reduces the OPC output complexity and improves turnaround time.

Claims

1. A method to analyze a layout pattern comprising one or more features to determine whether at least one shape of the pattern is suitable for rule-based optical proximity correction, comprising the steps of:

analyzing the pattern to identify a plurality of variable values;

calculating a region of sight based on the variable values;

specifying at least one performance metric specification for the at least one shape of the pattern for which a suitable correction rule is sought;

calculating a range of possible values for the at least one performance metric induced by uncertainties outside the region of sight by simulating the pattern using a lithography model; and

determining whether the at least one shape can be corrected by rule-based optical proximity correction dependent on whether there exists at least one correction rule to the at least one shape such that when the correction rule is applied, the range of possible values of the at least one performance metric is within the at least one performance metric specification.

2. The method of claim 1, further comprising the step of generating a correction rule for the at least one shape if the pattern is determined to be rule-correctable.

3. The method of claim 1 wherein the lithography model is a calibrated lithography model suitable for model-based optical proximity correction for the pattern.

4. The method of claim 1 wherein the performance metric specification consists of at least one error tolerance used for model-based optical proximity correction.

5. The method of claim 1 wherein the performance metric comprises at least one of the group of performance metrics consisting of the slope of an image, image contrast, mask error enhancement factor, sensitivity to focus variation, sensitivity to aberration, edge placement error, and critical dimension of a main feature including the at least one shape.

6. The method of claim 1 wherein the simulation is performed on at least one evaluation point on the at least one shape.

7. The method of claim 4 wherein the determination step comprises the step of tightening the tolerance specification by a specified amount.

8. The method of claim 1 wherein the pattern is characterized by a feature width and a feature height associated with the at least one shape.

9. The method of claim 8 wherein the pattern is further characterized by a neighbor spacing.

10. The method of claim 8 wherein the pattern is further characterized by at least one of a) a behind spacing, b) a specification of at least one vertical clearance area, and c) a specification of at least one vertical fill area.

11. The method of claim 1 wherein the pattern is characterized by a feature height and a neighbor spacing associated with the at least one shape.

12. The method of claim 11 wherein the pattern is further characterized by at least one of a) a neighbor width, b) at least one vertical clearance area, and c) at least one vertical fill area.

13. The method of claim 1 wherein the step of calculating a range for the at least one performance metric induced by uncertainties outside the region of sight by simulating the pattern using the lithography model comprises the steps of:

adding a plurality of perturbations outside the region of sight to create variations;

simulating the pattern for each perturbation using the lithography model and calculating the at least one performance metric; and

combining all values of the at least one performance metric to form a range for the at least one performance metric.

14. The method of claim 1 wherein the range of possible values of the at least one performance metric is within the at least one performance metric specification such that the at least one shape is rule-correctable, further comprising the steps of:

receiving an input layout; and

identifying layout patterns having the at least one shape that is rule-correctable using rule-based optical proximity correction.

15. The method of claim 14, further comprising the step of:

applying correction rules to the identified rule-correctable patterns.

16. The method of claim 15, further comprising the step of:

applying model-based optical proximity correction to the remainder of the layout to complete the optical proximity correction process.

17. A method to analyze layout patterns, comprising the steps of:

choosing at least two rule function variables;

selecting at least one value for each variable;

constructing at least one test pattern using the selected variable values conforming to a given set of design rules; and

determining whether each pattern is rule-correctable by;

a) calculating a region of sight based on the variable values;

b) specifying at least one performance metric specification for the at least one shape of the pattern for which a suitable correction rule is sought;

c) calculating a range of possible values for the at least one performance metric induced by uncertainties outside the region of sight by simulating the pattern using a lithography model; and

d) determining whether the at least one shape can be corrected by rule-based optical proximity correction dependent on whether there exists at least one correction rule to the at least one shape such that when the correction rule is applied, the range of possible values of the at least one performance metric is within the at least one performance metric specification.

18. The method of claim 17 wherein the lithography model is a calibrated lithography model suitable for model-based optical proximity correction for the pattern.

19. The method of claim 17 wherein the performance metric specification consists of at least one error tolerance used for model-based optical proximity correction.

20. The method of claim 17 wherein the performance metric comprises at least one of the group of performance metrics consisting of the slope of an image, image contrast, mask error enhancement factor, sensitivity to focus variation, sensitivity to aberration, edge placement error, and critical dimension of a main feature including the at least one shape.

21. The method of claim 17 wherein the simulation is performed on at least one evaluation point on the at least one shape.

22. The method of claim 19 wherein the determination step comprises the step of tightening the tolerance specification by a specified amount.

23. The method of claim 17 wherein the at least two rule function variables comprise a feature width and a feature height associated with the at least one shape.

24. The method of claim 23 wherein the at least two rule function variables further comprise a neighbor spacing.

25. The method of claim 23 wherein the at least two rule function variables further comprise at least one of a) a behind spacing, b) a specification of at least one vertical clearance area, and c) a specification of at least one vertical fill area.

26. The method of claim 17 wherein the at least two rule function variables comprise a feature height and a neighbor spacing associated with the at least one shape.

27. The method of claim 26 wherein the at least two rule function variables further comprise at least one of a) a neighbor width, b) at least one vertical clearance area, and c) at least one vertical fill area.

28. The method of claim 17 wherein the step of calculating a range for the at least one performance metric induced by uncertainties outside the region of sight by simulating the pattern using the lithography model comprises the steps of:

adding a plurality of perturbations outside the region of sight to create variations;

simulating the pattern for each perturbation using the lithography model and calculating the at least one performance metric; and

combining all values of the at least one performance metric to form a range for the at least one performance metric.

29. The method of claim 17, further comprising the steps of:

selecting patterns that are determined not to be rule-correctable;

adding at least one extra rule function variable, the at least one extra rule function variable being different from the at least two rule function variables;

selecting one or more values for the extra rule function variable; and

repeating steps a)-d) for the variable space that is previously considered not to be rule-correctable.

30. The method of claim 29 wherein the at least one extra rule function variable is at least one of a) a feature width associated with the at least one shape, b) a feature height associated with the at least one shape, c) a neighbor spacing, d) a behind spacing, e) a neighbor width, f) a specification of at least one vertical clearance area, and g) a specification of at least one vertical fill area different from the at least two rule function variables and wherein unless one of the at least two rule function variables is a neighbor spacing, the extra rule function variable is not a neighbor width and wherein unless one of the two rule function variables is a feature width, the extra rule function variable is not a behind spacing.

31. The method of claim 17, further comprising the step of generating a correction rule for each pattern that is determined to be rule-correctable.

32. The method of claim 31 wherein there is a plurality of correction rules and the rules are merged before they are exported.

33. The method of claim 17, further comprising the steps of:

receiving an input layout; and

identifying layout patterns that are rule-correctable using rule-based optical proximity correction.

34. The method of claim 33, further comprising the step of:

applying correction rules to the selected rule-correctable patterns.

35. The method of claim 34, further comprising the step of:

applying model-based optical proximity correction to the remainder of the layout to complete the optical proximity correction process.

36. A method to analyze a pattern comprising one or more features by simulating with a lithography model to determine whether a shape of the pattern is suitable for correction by a given rule, comprising the steps of:

analyzing the pattern to identify a plurality of variable values;

calculating a region of sight based on the variable values;

specifying at least one performance metric specification;

applying the given rule to correct the shape;

calculating a range of possible values for the at least one performance metric induced by one or more uncertainties outside the region of sight by simulating the pattern including the corrected shape using the lithography model; and

determining whether the range of possible values of the at least one performance metric is within the at least one performance metric specification when the given rule is applied.

37. The method of claim 36, further comprising the steps of:

receiving an input layout; and

identifying layout patterns that are rule-correctable by the given rule using rule-based optical proximity correction.

38. The method of claim 37, further comprising the step of:

applying the given rule to the identified rule-correctable patterns.

39. The method of claim 38, further comprising the step of:

applying model-based optical proximity correction to the remainder of the layout to complete the optical proximity correction process.

40. A system for analyzing a layout pattern comprising one or more features to determine whether at least one shape of the pattern is suitable for rule-based optical proximity correction, comprising:

means for analyzing the pattern to identify a plurality of variable values;

means for calculating a region of sight based on the variable values;

means for specifying at least one performance metric specification for the at least one shape of the pattern for which a suitable correction rule is sought based on at least one correction rule;

means for calculating a range of possible values for the at least one performance metric induced by uncertainties outside the region of sight by simulating the pattern using a lithography model; and

means for determining whether the at least one shape can be corrected by rule-based optical proximity correction dependent on whether there exists at least one correction rule to the at least one shape such that when the correction rule is applied, the range of possible values of the at least one performance metric is within the at least one performance metric specification.

41. The system of claim 40, further comprising means for generating a correction rule for the at least one shape if the pattern is determined to be rule-correctable.

42. The system of claim 40 wherein the lithography model is a calibrated lithography model suitable for model-based optical proximity correction for the pattern.

43. The system of claim 40 wherein the performance metric specification consists of at least one error tolerance used for model-based optical proximity correction.

44. The system of claim 40 wherein the performance metric comprises at least one of the group of performance metrics consisting of the slope of an image, image contrast, mask error enhancement factor, sensitivity to focus variation, sensitivity to aberration, edge placement error, and critical dimension of a main feature including the at least one shape.

45. The system of claim 40 wherein the simulation is performed on at least one evaluation point on the at least one shape.

46. The system of claim 43 wherein the determination means comprises means for tightening the tolerance specification by a specified amount.

47. The system of claim 40 wherein the pattern is characterized by a feature width and a feature height associated with the at least one shape.

48. The system of claim 47 wherein the pattern is further characterized by a neighbor spacing.

49. The system of claim 47 wherein the pattern is further characterized by at least one of a) a behind spacing, b) a specification of at least one vertical clearance area, and c) a specification of at least one vertical fill area.

50. The system of claim 40 wherein the pattern is characterized by a feature height and a neighbor spacing associated with the at least one shape.

51. The system of claim 50 wherein the pattern is further characterized by at least one of a) a neighbor width, b) at least one vertical clearance area, and c) at least one vertical fill area.

52. The system of claim 40 wherein the means for calculating a range for the at least one performance metric induced by uncertainties outside the region of sight by simulating the pattern using the lithography model comprises:

means for adding a plurality of perturbations outside the region of sight to create variations;

means for simulating the pattern for each perturbation using the lithography model and calculating the at least one performance metric; and

means for combining all values of the at least one performance metric to form a range for the at least one performance metric.

53. The system of claim 40 wherein the range of possible values of the at least one performance metric is within the at least one performance metric specification such that the at least one shape is rule-correctable, further comprising:

means for receiving an input layout; and

means for selecting layout patterns having the at least one shape that is rule-correctable using rule-based optical proximity correction.

54. The system of claim 53, further comprising means for applying correction rules to the identified rule-correctable patterns.

55. The system of claim 54, further comprising means for applying model-based optical proximity correction to the remainder of the layout to complete the optical proximity correction process.

56. A system for analyzing layout patterns, comprising:

means for choosing at least two rule function variables;

means for selecting at least one value for each variable;

means for constructing at least one test pattern using the selected variable values conforming to a given set of design rules; and

means for determining whether each pattern is rule-correctable by;

a) means for calculating a region of sight based on the variable values;

b) means for specifying at least one performance metric specification for the at least one shape of the pattern for which a suitable correction rule is sought;

c) means for calculating a range of possible values for the at least one performance metric induced by uncertainties outside the region of sight by simulating the pattern using a lithography model; and

d) means for determining whether the at least one shape can be corrected by rule-based optical proximity correction dependent on whether there exists at least one correction rule to the at least one shape such that when the correction rule is applied, the range of possible values of the at least one performance metric is within the at least one performance metric specification.

57. The system of claim 56 wherein the lithography model is a calibrated lithography model suitable for model-based optical proximity correction for the pattern.

58. The system of claim 56 wherein the performance metric specification consists of at least one error tolerance used for model-based optical proximity correction.

59. The system of claim 56 wherein the performance metric comprises at least one of the group of performance metrics consisting of the slope of an image, image contrast, mask error enhancement factor, sensitivity to focus variation, sensitivity to aberration, edge placement error, and critical dimension of a main feature including the at least one shape.

60. The system of claim 56 wherein the simulation is performed on at least one evaluation point on the at least one shape.

61. The system of claim 58 wherein the determination means comprises means for tightening the tolerance specification by a specified amount.

62. The system of claim 56 wherein the at least two rule function variables comprise a feature width and a feature height associated with the at least one shape.

63. The system of claim 62 wherein the at least two rule function variables further comprise a neighbor spacing.

64. The system of claim 62 wherein the at least two rule function variables further comprise at least one of a) a behind spacing, b) a specification of at least one vertical clearance area, and c) a specification of at least one vertical fill area.

65. The system of claim 56 wherein the at least two rule function variables comprise a feature height and a neighbor spacing associated with the at least one shape.

66. The system of claim 65 wherein the at least two rule function variables further comprise at least one of a) a neighbor width, b) at least one vertical clearance area, and c) at least one vertical fill area.

67. The system of claim 56 wherein the means for calculating a range for the at least one performance metric induced by uncertainties outside the region of sight by simulating the pattern using the lithography model comprises:

means for adding a plurality of perturbations outside the region of sight to create variations;

means for simulating the pattern for each perturbation using the lithography model and calculating the at least one performance metric; and

means for combining all values of the at least one performance metric to form a range for the at least one performance metric.

68. The system of claim 56, further comprising:

means for selecting patterns that are determined not to be rule-correctable;

means for adding at least one extra rule function variable, the at least one extra rule function variable being different from the at least two rule function variables;

means for selecting one or more values for the extra rule function variable; and

wherein patterns processed by the determination means comprise patterns for the variable space that is previously considered not rule-correctable.

69. The system of claim 68 wherein the at least one extra rule function variable is at least one of a) a feature width associated with the at least one shape, b) a feature height associated with the at least one shape, c) a neighbor spacing, d) a behind spacing, e) a neighbor width, f) a specification of at least one vertical clearance area, and g) a specification of at least one vertical fill area different from the at least two rule function variables and wherein unless one of the at least two rule function variables is a neighbor spacing, the extra rule function variable is not a neighbor width and wherein unless one of the two rule function variables is a feature width, the extra rule function variable is not a behind spacing.

70. The system of claim 56, further comprising the step of generating a correction rule for each pattern that is determined to be rule-correctable.

71. The system of claim 56 wherein there is a plurality of correction rules and the rules are merged before they are exported.

72. The method of claim 56, further comprising:

means for receiving an input layout; and

means for selecting layout patterns that are rule-correctable using rule-based optical proximity correction.

73. The method of claim 72, further comprising:

means for applying correction rules to the selected rule-correctable patterns.

74. The system of claim 73, further comprising:

means for applying model-based OPC to the remainder of the layout to complete the OPC process.

75. A system for analyzing a pattern comprising one or more features by simulating with a lithography model to determine whether a shape of the pattern is suitable for correction by a given rule, comprising:

means for analyzing the pattern to identify a plurality of variable values;

means for calculating a region of sight based on the variable values;

means for specifying at least one performance metric specification;

means for applying the given rule to correct the shape;

means for calculating a range of possible values for the at least one performance metric induced by one or more uncertainties outside the region of sight by simulating the pattern including the corrected shape using the lithography model; and

means for determining whether the range of possible values of the at least one performance metric is within the at least one performance metric specification when the given rule is applied.

76. The system of claim 75, further comprising:

means for receiving an input layout; and

means for identifying layout patterns that are rule-correctable by the given rule using rule-based optical proximity correction.

77. The system of claim 76, further comprising:

means for applying the given rule to the identified rule-correctable patterns.

78. The system of claim 77, further comprising:

means for applying model-based optical proximity correction to the remainder of the layout to complete the optical proximity correction process.