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Method for lithography model calibration
Assignee: ASML Netherlands BV
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Filing: 2006-08-02
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Granted: 2009-02-10
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Expires: 2026-08-02
Abstract
Abstract A method for separately calibrating an optical model and a resist model of lithography process using information derived from in-situ aerial image measurements to improve the calibration of both the optical model and the resist model components of the lithography simulation model. Aerial images produced by an exposure tool are measured using an image sensor array loaded into the exposure tool. Multiple embodiments of measuring aerial image information and using the measured aerial image information to calibrate the optical model and the resist model are disclosed. The method of the invention creates more accurate and separable optical and resist models, leading to better predictability of the pattern transfer process from mask to wafer, more accurate verification of circuit patterns and how they will actually print in production, and more accurate model-based process control in the wafer fabrication facility.
Inventors
- 👤 Jun Ye
- 👤 Yu Cao
- 👤 Guangqing Chen
- 👤 Stefan Hunsche
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 05:46
CPC Classifications
G; G03; G03F; G03F7/00; G03F7/70; G03F7/70483; G03F7/70491; G03F7/70516; G03F7/705
Claims Analysis
Total Claims: 110
Claim 1
Independent Claim
171 words
A method for lithography model calibration, comprising: selecting a model for a lithography process, the model including an optical model and a resist model, the optical model having initial values of optical model parameters and the resist model having initial values of resist model parameters; measuring an aerial image using an image sensor array to produce a measured sensor image, the aerial image being produced by a lithography tool from a mask created using circuit design data; simulating the lithography process using the optical model and the circuit design data to produce a simulated aerial image; determining differences between the simulated aerial image and the measured sensor image; and modifying the values of the optical model parameters based on the differences between the simulated aerial image and the measured sensor image to identify optimal values for the optical model parameters, wherein a simulated aerial image produced using the optimal values for the optical model parameters is an optimal simulated aerial image that is a best match for the measured sensor image.
Claim 2
Independent Claim
171 words
A method for lithography model calibration, comprising: selecting a model for a lithography process, the model including an optical model and a resist model, the optical model having initial values of optical model parameters and the resist model having initial values of resist model parameters; measuring an aerial image using an image sensor array to produce a measured sensor image, the aerial image being produced by a lithography tool from a mask created using circuit design data; simulating the lithography process using the optical model and the circuit design data to produce a simulated aerial image; determining differences between the simulated aerial image and the measured sensor image; and modifying the values of the optical model parameters based on the differences between the simulated aerial image and the measured sensor image to identify optimal values for the optical model parameters, wherein a simulated aerial image produced using the optimal values for the optical model parameters is an optimal simulated aerial image that is a best match for the measured sensor image.
Claim 3
Dependent Claim
129 words
The method of claim 1 , further comprising: processing a wafer using the lithography process and the mask to produce printed resist patterns; measuring the printed resist patterns to produce measured resist patterns; simulating formation of resist patterns on a wafer using the resist model and the optimal simulated aerial image to produce simulated resist patterns; determining differences between the simulated resist patterns and the measured resist patterns; and modifying the values of the resist model parameters based on the differences between the simulated resist patterns and the measured resist patterns to identify optimal values for the resist model parameters, wherein simulated resist patterns produced using the optimal values for the resist model parameters are optimal simulated resist patterns that are a best match for the measured resist patterns.
Claim 4
Dependent Claim
57 words
The method of claim 2 , wherein the optimal values for the resist model parameters are identified using one or more of a set of fitting algorithms, the set of fitting algorithms including minimizing Root-Mean-Square (RMS) errors, removing outliers, minimizing maximum residual errors, and using weighting factors to preferentially fit specific points, regions, metrics, or optical conditions.
Claim 5
Dependent Claim
37 words
The method of claim 2 , wherein the differences between the simulated resist patterns and the measured resist patterns include one or more values of critical dimension, resist thickness, sidewall angle, resist profile, footing, and top-profile rounding.
Claim 6
Dependent Claim
57 words
The method of claim 1 , wherein the optimal values for the optical model parameters are identified using one or more of a set of fitting algorithms, the set of fitting algorithms including minimizing Root-Mean-Square (RMS) errors, removing outliers, minimizing maximum residual errors, and using weighting factors to preferentially fit specific points, regions, metrics, or optical conditions.
Claim 7
Dependent Claim
38 words
The method of claim 1 , wherein the differences between the simulated aerial image and the measured sensor image include one or more values of image intensity, image slope, image contrast, critical dimension, line-end pullback, and corner rounding.
Claim 8
Dependent Claim
32 words
The method of claim 1 , wherein the image sensor array is disposed in an image sensor unit that is capable of being loaded into the wafer stage of an exposure tool.
Claim 9
Dependent Claim
25 words
The method of claim 1 , wherein the image sensor array is disposed in an image sensor unit that is integrated into an exposure tool.
Claim 10
Dependent Claim
17 words
The method of claim 1 , wherein the circuit design data are a set of calibration patterns.
Claim 11
Dependent Claim
29 words
The method of claim 9 , wherein the set of calibration patterns includes patterns covering a wide area of a pattern parameter space that are sensitive to process variations.
Claim 12
Dependent Claim
16 words
The method of claim 10 , wherein the patterns have varying values of size and pitch.
Claim 13
Dependent Claim
21 words
The method of claim 9 , wherein the set of calibration patterns includes line-space patterns, contacts, line-ends, and brick wall patterns.
Claim 14
Dependent Claim
33 words
The method of claim 9 , wherein the set of calibration patterns includes line-space patterns with varying values of orientation, hexagonal patterns, or brick wall patterns for optimal calibration of optical aberration parameters.
Claim 15
Dependent Claim
29 words
The method of claim 1 , wherein simulating the lithography process and measuring the aerial image are performed for a range of patterns, process window conditions, and optical conditions.
Claim 16
Dependent Claim
24 words
The method of claim 14 , wherein the range of patterns includes one or more of line-space patterns with varying pitch and line-end patterns.
Claim 17
Dependent Claim
22 words
The method of claim 14 , wherein the process window conditions include one or more varying values of focus and exposure dose.
Claim 18
Dependent Claim
22 words
The method of claim 14 , wherein the optical conditions include one or more varying values of numerical aperture and partial coherence.
Claim 19
Independent Claim
208 words
A method for calibrating a model of a lithography process, comprising: selecting a model for a lithography process, the model including an optical model and a resist model, the optical model having initial values of optical model parameters; selecting a sensor model for an image sensor array, the sensor model having initial values of sensor model parameters; measuring an aerial image using the image sensor array to produce a measured sensor image, the aerial image being produced by a lithography tool from a mask created using circuit design data; simulating behavior of the image sensor array using the optical model, the sensor model, and the circuit design data to produce a simulated sensor image; determining differences between the measured sensor image and the simulated sensor image; and modifying the optical model parameters and the sensor model parameters based on the differences between the measured sensor image and the simulated sensor image to identify optimal values for the optical model parameters and optimal values for the sensor model parameters, wherein a simulated sensor image produced using the optimal values for the optical model parameters and the optimal values for the sensor model parameters is an optimal simulated sensor image that is a best match for the measured sensor image.
Claim 20
Independent Claim
208 words
A method for calibrating a model of a lithography process, comprising: selecting a model for a lithography process, the model including an optical model and a resist model, the optical model having initial values of optical model parameters; selecting a sensor model for an image sensor array, the sensor model having initial values of sensor model parameters; measuring an aerial image using the image sensor array to produce a measured sensor image, the aerial image being produced by a lithography tool from a mask created using circuit design data; simulating behavior of the image sensor array using the optical model, the sensor model, and the circuit design data to produce a simulated sensor image; determining differences between the measured sensor image and the simulated sensor image; and modifying the optical model parameters and the sensor model parameters based on the differences between the measured sensor image and the simulated sensor image to identify optimal values for the optical model parameters and optimal values for the sensor model parameters, wherein a simulated sensor image produced using the optimal values for the optical model parameters and the optimal values for the sensor model parameters is an optimal simulated sensor image that is a best match for the measured sensor image.
Claim 21
Dependent Claim
150 words
The method of claim 18 , further comprising: processing a wafer using the lithography process and the mask to produce printed resist patterns; measuring the printed resist patterns to produce measured resist patterns; simulating the lithography process using the optical model with the optimal optical model parameters to produce an optimal simulated aerial image; simulating formation of resist patterns on a wafer using the resist model and the optimal simulated aerial image to produce simulated resist patterns; determining differences between the simulated resist patterns and the measured resist patterns; and modifying the values of the resist model parameters based on the differences between the simulated resist patterns and the measured resist patterns to identify optimal values for the resist model parameters, wherein simulated resist patterns produced using the optimal values for the resist model parameters are optimal simulated resist patterns that are a best match for the measured resist patterns.
Claim 22
Dependent Claim
57 words
The method of claim 19 , wherein the optimal values for the resist model parameters are identified using one or more of a set of fitting algorithms, the set of fitting algorithms including minimizing Root-Mean-Square (RMS) errors, removing outliers, minimizing maximum residual errors, and using weighting factors to preferentially fit specific points, regions, metrics, or optical conditions.
Claim 23
Dependent Claim
37 words
The method of claim 19 , wherein the differences between the simulated resist patterns and the measured resist patterns include one or more values of critical dimension, resist thickness, sidewall angle, resist profile, footing, and top-profile rounding.
Claim 24
Dependent Claim
66 words
The method of claim 18 , wherein the optimal values for the optical model parameters and the optimal values for the sensor model parameters are identified using one or more of a set of fitting algorithms, the set of fitting algorithms including minimizing Root-Mean-Square (RMS) errors, removing outliers, minimizing maximum residual errors, and using weighting factors to preferentially fit specific points, regions, metrics, or optical conditions.
Claim 25
Dependent Claim
38 words
The method of claim 18 , wherein the differences between the measured sensor image and the simulated sensor image include one or more values of image intensity, image slope, image contrast, critical dimension, line-end pullback, and corner rounding.
Claim 26
Dependent Claim
32 words
The method of claim 18 , wherein the image sensor array is disposed in an image sensor unit that is capable of being loaded into the wafer stage of an exposure tool.
Claim 27
Dependent Claim
23 words
The method of claim 18 , wherein the image sensor array is disposed in an image sensor unit integrated into an exposure tool.
Claim 28
Dependent Claim
17 words
The method of claim 18 , wherein the circuit design data are a set of calibration patterns.
Claim 29
Dependent Claim
29 words
The method of claim 26 , wherein the set of calibration patterns includes patterns covering a wide area of a pattern parameter space that are sensitive to process variations.
Claim 30
Dependent Claim
16 words
The method of claim 27 , wherein the patterns have varying values of size and pitch.
Claim 31
Dependent Claim
21 words
The method of claim 26 , wherein the set of calibration patterns includes line-space patterns, contacts, line-ends, and brick wall patterns.
Claim 32
Dependent Claim
33 words
The method of claim 26 , wherein the set of calibration patterns includes line-space patterns with varying values of orientation, hexagonal patterns, or brick wall patterns for optimal calibration of optical aberration parameters.
Claim 33
Dependent Claim
32 words
The method of claim 18 , wherein simulating behavior of the image sensor array and measuring the aerial image are performed for a range of patterns, process window conditions, and optical conditions.
Claim 34
Dependent Claim
24 words
The method of claim 31 , wherein the range of patterns includes one or more of line-space patterns with varying pitch and line-end patterns.
Claim 35
Dependent Claim
22 words
The method of claim 31 , wherein the process window conditions include one or more varying values of focus and exposure dose.
Claim 36
Dependent Claim
22 words
The method of claim 31 , wherein the optical conditions include one or more varying values of numerical aperture and partial coherence.
Claim 37
Independent Claim
224 words
A method for calibrating a model of a lithography process, comprising: selecting a model for a lithography process, the model including an optical model and a resist model, the optical model having initial values of optical model parameters; selecting a sensor model for an image sensor array, the sensor model having initial values of sensor model parameters; measuring an aerial image using the image sensor array to produce a measured sensor image, the aerial image being produced by a lithography tool from a mask created using circuit design data; simulating the lithography process using the optical model and the circuit design data to produce a simulated aerial image; simulating behavior of the image sensor array using the simulated aerial image and the sensor model to produce a simulated sensor image; determining differences between the measured sensor image and the simulated sensor image; and modifying the optical model parameters and the sensor model parameters based on the differences between the measured sensor image and the simulated sensor image to identify optimal values for the optical model parameters and optimal values for the sensor model parameters, wherein a simulated sensor image produced using the optimal values for the optical model parameters and the optimal values for the sensor model parameters is an optimal simulated sensor image that is a best match for the measured sensor image.
Claim 38
Independent Claim
224 words
A method for calibrating a model of a lithography process, comprising: selecting a model for a lithography process, the model including an optical model and a resist model, the optical model having initial values of optical model parameters; selecting a sensor model for an image sensor array, the sensor model having initial values of sensor model parameters; measuring an aerial image using the image sensor array to produce a measured sensor image, the aerial image being produced by a lithography tool from a mask created using circuit design data; simulating the lithography process using the optical model and the circuit design data to produce a simulated aerial image; simulating behavior of the image sensor array using the simulated aerial image and the sensor model to produce a simulated sensor image; determining differences between the measured sensor image and the simulated sensor image; and modifying the optical model parameters and the sensor model parameters based on the differences between the measured sensor image and the simulated sensor image to identify optimal values for the optical model parameters and optimal values for the sensor model parameters, wherein a simulated sensor image produced using the optimal values for the optical model parameters and the optimal values for the sensor model parameters is an optimal simulated sensor image that is a best match for the measured sensor image.
Claim 39
Dependent Claim
152 words
The method of claim 35 , further comprising: processing a wafer using the lithography process and the mask to produce printed resist patterns; measuring the printed resist patterns to produce measured resist patterns; simulating the lithography process using the optical model with the optimal optical model parameters to produce an optimal simulated aerial image; simulating formation of resist patterns on a wafer using the resist model and the optimal simulated aerial image to produce simulated resist patterns; determining differences between the simulated resist patterns and the measured resist patterns; and modifying values of resist model parameters of the resist model based on the differences between the simulated resist patterns and the measured resist patterns to identify optimal values for the resist model parameters, wherein simulated resist patterns produced using the optimal values for the resist model parameters are optimal simulated resist patterns that are a best match for the measured resist patterns.
Claim 40
Dependent Claim
57 words
The method of claim 36 , wherein the optimal values for the resist model parameters are identified using one or more of a set of fitting algorithms, the set of fitting algorithms including minimizing Root-Mean-Square (RMS) errors, removing outliers, minimizing maximum residual errors, and using weighting factors to preferentially fit specific points, regions, metrics, or optical conditions.
Claim 41
Dependent Claim
37 words
The method of claim 36 , wherein the differences between the simulated resist patterns and the measured resist patterns include one or more values of critical dimension, resist thickness, sidewall angle, resist profile, footing, and top-profile rounding.
Claim 42
Dependent Claim
131 words
The method of claim 35 , further comprising: processing a wafer using the lithography process and the mask to produce printed resist patterns; measuring the printed resist patterns to produce measured resist patterns; simulating formation of resist patterns on a wafer using the resist model and the optimal simulated sensor image to produce simulated resist patterns; determining differences between the simulated resist patterns and the measured resist patterns; and modifying values of resist model parameters of the resist model based on the differences between the simulated resist patterns and the measured resist patterns to identify optimal values for the resist model parameters, wherein simulated resist patterns produced using the optimal values for the resist model parameters are optimal simulated resist patterns that are a best match for the measured resist patterns.
Claim 43
Dependent Claim
57 words
The method of claim 39 , wherein the optimal values for the resist model parameters are identified using one or more of a set of fitting algorithms, the set of fitting algorithms including minimizing Root-Mean-Square (RMS) errors, removing outliers, minimizing maximum residual errors, and using weighting factors to preferentially fit specific points, regions, metrics, or optical conditions.
Claim 44
Dependent Claim
37 words
The method of claim 39 , wherein the differences between the simulated resist patterns and the measured resist patterns include one or more values of critical dimension, resist thickness, sidewall angle, resist profile, footing, and top-profile rounding.
Claim 45
Dependent Claim
66 words
The method of claim 35 , wherein the optimal values for the optical model parameters and the optimal values for the sensor model parameters are identified using one or more of a set of fitting algorithms, the set of fitting algorithms including minimizing Root-Mean-Square (RMS) errors, removing outliers, minimizing maximum residual errors, and using weighting factors to preferentially fit specific points, regions, metrics, or optical conditions.
Claim 46
Dependent Claim
38 words
The method of claim 35 , wherein the differences between the simulated aerial image and the measured sensor image include one or more values of image intensity, image slope, image contrast, critical dimension, line-end pullback, and corner rounding.
Claim 47
Dependent Claim
32 words
The method of claim 35 , wherein the image sensor array is disposed in an image sensor unit that is capable of being loaded into the wafer stage of an exposure tool.
Claim 48
Dependent Claim
23 words
The method of claim 35 , wherein the image sensor array is disposed in an image sensor unit integrated into an exposure tool.
Claim 49
Dependent Claim
17 words
The method of claim 35 , wherein the circuit design data are a set of calibration patterns.
Claim 50
Dependent Claim
29 words
The method of claim 46 , wherein the set of calibration patterns includes patterns covering a wide area of a pattern parameter space that are sensitive to process variations.
Claim 51
Dependent Claim
16 words
The method of claim 47 , wherein the patterns have varying values of size and pitch.
Claim 52
Dependent Claim
21 words
The method of claim 46 , wherein the set of calibration patterns includes line-space patterns, contacts, line-ends, and brick wall patterns.
Claim 53
Dependent Claim
33 words
The method of claim 46 , wherein the set of calibration patterns includes line-space patterns with varying values of orientation, hexagonal patterns, or brick wall patterns for optimal calibration of optical aberration parameters.
Claim 54
Dependent Claim
36 words
The method of claim 35 , wherein simulating the lithography process, simulating behavior of the image sensor array, and measuring the aerial image are performed for a range of patterns, process window conditions, and optical conditions.
Claim 55
Dependent Claim
24 words
The method of claim 51 , wherein the range of patterns includes one or more of line-space patterns with varying pitch and line-end patterns.
Claim 56
Dependent Claim
22 words
The method of claim 51 , wherein the process window conditions include one or more varying values of focus and exposure dose.
Claim 57
Dependent Claim
22 words
The method of claim 51 , wherein the optical conditions include one or more varying values of numerical aperture and partial coherence.
Claim 58
Independent Claim
224 words
A method for calibrating a model of a lithography process, comprising: selecting a model for a lithography process, the model including an optical model and a resist model, the optical model having initial values of optical model parameters and the resist model having initial values of resist model parameters; selecting an inverse sensor model for an image sensor array, the inverse sensor model having initial values of inverse sensor model parameters; measuring an aerial image using the image sensor array to produce a measured sensor image, the aerial image being produced by a lithography tool from a mask created using circuit design data; generating a reconstructed aerial image using the measured sensor image and the inverse sensor model; simulating the lithography process using the optical model and the circuit design data to produce a simulated aerial image; determining differences between the simulated aerial image and the reconstructed aerial image; and modifying the optical model parameters and the inverse sensor model parameters based on the differences between the simulated aerial image and the reconstructed aerial image to identify optimal values for the optical model parameters and optimal values for the inverse sensor model parameters, wherein a simulated aerial image produced using the optimal values for the optical model parameters is an optimal simulated aerial image that is a best match for the reconstructed aerial image.
Claim 59
Independent Claim
224 words
A method for calibrating a model of a lithography process, comprising: selecting a model for a lithography process, the model including an optical model and a resist model, the optical model having initial values of optical model parameters and the resist model having initial values of resist model parameters; selecting an inverse sensor model for an image sensor array, the inverse sensor model having initial values of inverse sensor model parameters; measuring an aerial image using the image sensor array to produce a measured sensor image, the aerial image being produced by a lithography tool from a mask created using circuit design data; generating a reconstructed aerial image using the measured sensor image and the inverse sensor model; simulating the lithography process using the optical model and the circuit design data to produce a simulated aerial image; determining differences between the simulated aerial image and the reconstructed aerial image; and modifying the optical model parameters and the inverse sensor model parameters based on the differences between the simulated aerial image and the reconstructed aerial image to identify optimal values for the optical model parameters and optimal values for the inverse sensor model parameters, wherein a simulated aerial image produced using the optimal values for the optical model parameters is an optimal simulated aerial image that is a best match for the reconstructed aerial image.
Claim 60
Dependent Claim
129 words
The method of claim 55 , further comprising: processing a wafer using the lithography process and the mask to produce printed resist patterns; measuring the printed resist patterns to produce measured resist patterns; simulating formation of resist patterns on a wafer using the resist model and the optimal simulated aerial image to produce simulated resist patterns; determining differences between the simulated resist patterns and the measured resist patterns; and modifying the values of the resist model parameters based on the differences between the simulated resist patterns and the measured resist patterns to identify optimal values for the resist model parameters, wherein simulated resist patterns produced using the optimal values for the resist model parameters are optimal simulated resist patterns that are a best match for the measured resist patterns.
Claim 61
Dependent Claim
57 words
The method of claim 56 , wherein the optimal values for the resist model parameters are identified using one or more of a set of fitting algorithms, the set of fitting algorithms including minimizing Root-Mean-Square (RMS) errors, removing outliers, minimizing maximum residual errors, and using weighting factors to preferentially fit specific points, regions, metrics, or optical conditions.
Claim 62
Dependent Claim
37 words
The method of claim 56 , wherein the differences between the simulated resist patterns and the measured resist patterns include one or more values of critical dimension, resist thickness, sidewall angle, resist profile, footing, and top-profile rounding.
Claim 63
Dependent Claim
67 words
The method of claim 55 , wherein the optimal values for the optical model parameters and the optimal values for the inverse sensor model parameters are identified using one or more of a set of fitting algorithms, the set of fitting algorithms including minimizing Root-Mean-Square (RMS) errors, removing outliers, minimizing maximum residual errors, and using weighting factors to preferentially fit specific points, regions, metrics, or optical conditions.
Claim 64
Dependent Claim
38 words
The method of claim 55 , wherein the differences between the simulated aerial image and the reconstructed aerial image include one or more values of image intensity, image slope, image contrast, critical dimension, line-end pullback, and corner rounding.
Claim 65
Dependent Claim
30 words
The method of claim 55 , wherein the image sensor array is disposed in an image sensor unit capable of being loaded into the wafer stage of an exposure tool.
Claim 66
Dependent Claim
25 words
The method of claim 55 , wherein the image sensor array is disposed in an image sensor unit that is integrated into an exposure tool.
Claim 67
Dependent Claim
17 words
The method of claim 55 , wherein the circuit design data are a set of calibration patterns.
Claim 68
Dependent Claim
29 words
The method of claim 63 , wherein the set of calibration patterns includes patterns covering a wide area of a pattern parameter space that are sensitive to process variations.
Claim 69
Dependent Claim
16 words
The method of claim 64 , wherein the patterns have varying values of size and pitch.
Claim 70
Dependent Claim
21 words
The method of claim 63 , wherein the set of calibration patterns includes line-space patterns, contacts, line-ends, and brick wall patterns.
Claim 71
Dependent Claim
33 words
The method of claim 63 , wherein the set of calibration patterns includes line-space patterns with varying values of orientation, hexagonal patterns, or brick wall patterns for optimal calibration of optical aberration parameters.
Claim 72
Dependent Claim
34 words
The method of claim 55 , wherein measuring the aerial image, generating the reconstructed aerial image, and simulating the lithography process are performed for a range of patterns, process window conditions, and optical conditions.
Claim 73
Dependent Claim
24 words
The method of claim 68 , wherein the range of patterns includes one or more of line-space patterns with varying pitch and line-end patterns.
Claim 74
Dependent Claim
22 words
The method of claim 68 , wherein the process window conditions include one or more varying values of focus and exposure dose.
Claim 75
Dependent Claim
22 words
The method of claim 68 , wherein the optical conditions include one or more varying values of numerical aperture and partial coherence.
Claim 76
Independent Claim
335 words
A method for calibrating a model of a lithography process, comprising: selecting a model for a lithography process, the model including an optical model and a resist model, the optical model having initial values of optical model parameters and the resist model having initial values of resist model parameters; selecting a sensor model for an image sensor array, the sensor model having values of sensor model parameters; measuring an aerial image using the image sensor array to produce a measured sensor image, the aerial image being produced by a lithography tool from a mask created using circuit design data; processing a wafer using the lithography process and the mask to produce printed resist patterns; measuring the printed resist patterns to produce measured resist patterns; simulating behavior of the image sensor array using the optical model, the circuit design data, and the sensor model to produce a simulated sensor image; determining differences between the measured sensor image and the simulated sensor image; simulating the lithography process using the optical model and the circuit design data to produce a simulated aerial image; simulating formation of resist patterns on a wafer using the resist model and the simulated aerial image to produce simulated resist patterns; determining differences between the simulated resist patterns and the measured resist patterns; and modifying the values of the optical model parameters and the resist model parameters based on a total difference between the simulated resist patterns and the measured resist patterns as well as between the measured sensor image and the simulated sensor image to identify optimal values for the optical model parameters and optimal values for the resist model parameters simultaneously, wherein simulated resist patterns produced using the optimal values for the resist model parameters are optimal simulated resist patterns that are a best match for the measured resist patterns, and wherein a simulated sensor image produced using the optimal values for the optical model parameters is an optimal simulated sensor image that is a best match for the measured sensor image.
Claim 77
Independent Claim
335 words
A method for calibrating a model of a lithography process, comprising: selecting a model for a lithography process, the model including an optical model and a resist model, the optical model having initial values of optical model parameters and the resist model having initial values of resist model parameters; selecting a sensor model for an image sensor array, the sensor model having values of sensor model parameters; measuring an aerial image using the image sensor array to produce a measured sensor image, the aerial image being produced by a lithography tool from a mask created using circuit design data; processing a wafer using the lithography process and the mask to produce printed resist patterns; measuring the printed resist patterns to produce measured resist patterns; simulating behavior of the image sensor array using the optical model, the circuit design data, and the sensor model to produce a simulated sensor image; determining differences between the measured sensor image and the simulated sensor image; simulating the lithography process using the optical model and the circuit design data to produce a simulated aerial image; simulating formation of resist patterns on a wafer using the resist model and the simulated aerial image to produce simulated resist patterns; determining differences between the simulated resist patterns and the measured resist patterns; and modifying the values of the optical model parameters and the resist model parameters based on a total difference between the simulated resist patterns and the measured resist patterns as well as between the measured sensor image and the simulated sensor image to identify optimal values for the optical model parameters and optimal values for the resist model parameters simultaneously, wherein simulated resist patterns produced using the optimal values for the resist model parameters are optimal simulated resist patterns that are a best match for the measured resist patterns, and wherein a simulated sensor image produced using the optimal values for the optical model parameters is an optimal simulated sensor image that is a best match for the measured sensor image.
Claim 78
Dependent Claim
66 words
The method of claim 72 , wherein the optimal values for the optical model parameters and the optimal values for the resist model parameters are identified using one or more of a set of fitting algorithms, the set of fitting algorithms including minimizing Root-Mean-Square (RMS) errors, removing outliers, minimizing maximum residual errors, and using weighting factors to preferentially fit specific points, regions, metrics, or optical conditions.
Claim 79
Dependent Claim
38 words
The method of claim 72 , wherein the differences between the simulated sensor image and the measured sensor image include one or more values of image intensity, image slope, image contrast, critical dimension, line-end pullback, and corner rounding.
Claim 80
Dependent Claim
37 words
The method of claim 72 , wherein the differences between the simulated resist patterns and the measured resist patterns include one or more values of critical dimension, resist thickness, sidewall angle, resist profile, footing, and top-profile rounding.
Claim 81
Dependent Claim
32 words
The method of claim 72 , wherein the image sensor array is disposed in an image sensor unit that is capable of being loaded into the wafer stage of an exposure tool.
Claim 82
Dependent Claim
25 words
The method of claim 72 , wherein the image sensor array is disposed in an image sensor unit that is integrated into an exposure tool.
Claim 83
Dependent Claim
17 words
The method of claim 72 , wherein the circuit design data are a set of calibration patterns.
Claim 84
Dependent Claim
29 words
The method of claim 78 , wherein the set of calibration patterns includes patterns covering a wide area of a pattern parameter space that are sensitive to process variations.
Claim 85
Dependent Claim
16 words
The method of claim 79 , wherein the patterns have varying values of size and pitch.
Claim 86
Dependent Claim
21 words
The method of claim 78 , wherein the set of calibration patterns includes line-space patterns, contacts, line-ends, and brick wall patterns.
Claim 87
Dependent Claim
33 words
The method of claim 78 , wherein the set of calibration patterns includes line-space patterns with varying values of orientation, hexagonal patterns, or brick wall patterns for optimal calibration of optical aberration parameters.
Claim 88
Dependent Claim
36 words
The method of claim 72 , wherein simulating the lithography process, simulating behavior of the image sensor array, and measuring the aerial image are performed for a range of patterns, process window conditions, and optical conditions.
Claim 89
Dependent Claim
24 words
The method of claim 83 , wherein the range of patterns includes one or more of line-space patterns with varying pitch and line-end patterns.
Claim 90
Dependent Claim
22 words
The method of claim 83 , wherein the process window conditions include one or more varying values of focus and exposure dose.
Claim 91
Dependent Claim
22 words
The method of claim 83 , wherein the optical conditions include one or more varying values of numerical aperture and partial coherence.
Claim 92
Dependent Claim
239 words
A computer-readable medium containing instructions for calibrating a model of a lithography process by performing: storing a model for a lithography process, the model including an optical model and a resist model, the optical model having initial values of optical model parameters, and the resist model having initial values of resist model parameters; storing a sensor model for an image sensor array, the sensor model having initial values of sensor model parameters; receiving a measured sensor image produced by measuring an aerial image using the image sensor array, the aerial image produced by a lithography tool from a mask created using circuit design data; simulating the lithography process using the optical model and the circuit design data to produce a simulated aerial image; simulating behavior of the image sensor array using the simulated aerial image and the sensor model to produce a simulated sensor image; determining differences between the simulated sensor image and the measured sensor image; and modifying the optical model parameters and the sensor model parameters based on the differences between the simulated sensor image and the measured sensor image to identify optimal values for the optical model parameters and optimal values for the sensor model parameters, wherein a simulated sensor image produced using the optimal values for the optical model parameters and the optimal values for the sensor model parameters is an optimal simulated sensor image that is a best match for the measured sensor image.
Claim 93
Dependent Claim
239 words
A computer-readable medium containing instructions for calibrating a model of a lithography process by performing: storing a model for a lithography process, the model including an optical model and a resist model, the optical model having initial values of optical model parameters, and the resist model having initial values of resist model parameters; storing a sensor model for an image sensor array, the sensor model having initial values of sensor model parameters; receiving a measured sensor image produced by measuring an aerial image using the image sensor array, the aerial image produced by a lithography tool from a mask created using circuit design data; simulating the lithography process using the optical model and the circuit design data to produce a simulated aerial image; simulating behavior of the image sensor array using the simulated aerial image and the sensor model to produce a simulated sensor image; determining differences between the simulated sensor image and the measured sensor image; and modifying the optical model parameters and the sensor model parameters based on the differences between the simulated sensor image and the measured sensor image to identify optimal values for the optical model parameters and optimal values for the sensor model parameters, wherein a simulated sensor image produced using the optimal values for the optical model parameters and the optimal values for the sensor model parameters is an optimal simulated sensor image that is a best match for the measured sensor image.
Claim 94
Dependent Claim
149 words
The computer-readable medium of claim 87 , containing further instructions for performing: receiving measured resist patterns of resist patterns printed onto a wafer using the lithography process and the mask; simulating the lithography process using the optical model with the optimal optical model parameters to produce an optimal simulated aerial image; simulating formation of resist patterns on a wafer using the resist model and the optimal simulated aerial image to produce simulated resist patterns; determining differences between the simulated resist patterns and the measured resist patterns; and modifying values of resist model parameters of the resist model based on the differences between the simulated resist patterns and the measured resist patterns to identify optimal values for the resist model parameters, wherein simulated resist patterns produced using the optimal values for the resist model parameters are optimal simulated resist patterns that are a best match for the measured resist patterns.
Claim 95
Dependent Claim
58 words
The computer-readable medium of claim 88 , wherein the optimal values for the resist model parameters are identified using one or more of a set of fitting algorithms, the set of fitting algorithms including minimizing Root-Mean-Square (RMS) errors, removing outliers, minimizing maximum residual errors, and using weighting factors to preferentially fit specific points, regions, metrics, or optical conditions.
Claim 96
Dependent Claim
38 words
The computer-readable medium of claim 88 , wherein the differences between the simulated resist patterns and the measured resist patterns include one or more values of critical dimension, resist thickness, sidewall angle, resist profile, footing, and top-profile rounding.
Claim 97
Dependent Claim
126 words
The computer-readable medium of claim 87 , containing further instructions for performing: receiving measured resist patterns of resist patterns printed onto a wafer using the lithography process and the mask; simulating formation of resist patterns on a wafer using the resist model and the optimal simulated sensor image to produce simulated resist patterns; determining differences between the simulated resist patterns and the measured resist patterns; and modifying the values of the resist model parameters based on the differences between the simulated resist patterns and the measured resist patterns to identify optimal values for the resist model parameters, wherein simulated resist patterns produced using the optimal values for the resist model parameters are optimal simulated resist patterns that are a best match for the measured resist patterns.
Claim 98
Dependent Claim
58 words
The computer-readable medium of claim 91 , wherein the optimal values for the resist model parameters are identified using one or more of a set of fitting algorithms, the set of fitting algorithms including minimizing Root-Mean-Square (RMS) errors, removing outliers, minimizing maximum residual errors, and using weighting factors to preferentially fit specific points, regions, metrics, or optical conditions.
Claim 99
Dependent Claim
38 words
The computer-readable medium of claim 91 , wherein the differences between the simulated resist patterns and the measured resist patterns include one or more values of critical dimension, resist thickness, sidewall angle, resist profile, footing, and top-profile rounding.
Claim 100
Dependent Claim
67 words
The computer-readable medium of claim 87 , wherein the optimal values for the optical model parameters and the optimal values for the sensor model parameters are identified using one or more of a set of fitting algorithms, the set of fitting algorithms including minimizing Root-Mean-Square (RMS) errors, removing outliers, minimizing maximum residual errors, and using weighting factors to preferentially fit specific points, regions, metrics, or optical conditions.
Claim 101
Dependent Claim
39 words
The computer-readable medium of claim 87 , wherein the differences between the simulated sensor image and the measured sensor image include one or more values of image intensity, image slope, image contrast, critical dimension, line-end pullback, and corner rounding.
Claim 102
Dependent Claim
18 words
The computer-readable medium of claim 87 , wherein the circuit design data are a set of calibration patterns.
Claim 103
Dependent Claim
30 words
The computer-readable medium of claim 96 , wherein the set of calibration patterns includes patterns covering a wide area of a pattern parameter space that are sensitive to process variations.
Claim 104
Dependent Claim
17 words
The computer-readable medium of claim 97 , wherein the patterns have varying values of size and pitch.
Claim 105
Dependent Claim
22 words
The computer-readable medium of claim 96 , wherein the set of calibration patterns includes line-space patterns, contacts, line-ends, and brick wall patterns.
Claim 106
Dependent Claim
34 words
The computer-readable medium of claim 96 , wherein the set of calibration patterns includes line-space patterns with varying values of orientation, hexagonal patterns, or brick wall patterns for optimal calibration of optical aberration parameters.
Claim 107
Dependent Claim
30 words
The computer-readable medium of claim 87 , wherein simulating the lithography process and measuring the aerial image are performed for a range of patterns, process window conditions, and optical conditions.
Claim 108
Dependent Claim
25 words
The computer-readable medium of claim 101 , wherein the range of patterns includes one or more of line-space patterns with varying pitch and line-end patterns.
Claim 109
Dependent Claim
23 words
The computer-readable medium of claim 101 , wherein the process window conditions include one or more varying values of focus and exposure dose.
Claim 110
Dependent Claim
23 words
The computer-readable medium of claim 101 , wherein the optical conditions include one or more varying values of numerical aperture and partial coherence.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2012-02-10 | 2012-08-11 | 2013-02-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2016-02-10 | 2016-08-11 | 2017-02-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2020-02-10 | 2020-08-11 | 2021-02-10 | $7700.00 | Window Closed / Lapsed |