Patent US6178360B1 successfully refreshed from Google Patents.
US6178360B1
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US
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Methods and apparatus for determining optimum exposure threshold for a given photolithographic model
Assignee: Micron Technology Inc
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Filing: 1998-02-05
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Granted: 2001-01-23
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Expires: 2018-02-05
Abstract
Abstract A system and method for enhancing process latitude (tolerances) in the fabrication of devices and integrated circuits. A measuring point is selected corresponding to a feature of critical dimension. Then the pattern is convolved with the model, and its value and rate of change are calculated over a range of corresponding values of a first process parameter. Next, an optimum threshold having the largest rate of change, or contrast, is selected. Finally, proximity correction is performed using relevant parameters.
Inventors
- 👤 Christophe Pierrat
- 👤 James Burdorf
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 02:45
CPC Classifications
G; G03; G03F; G03F7/00; G03F7/70; G03F7/70483; G03F7/7055; G03F7/70558; C; C09; C09K; C09K8/00; C09K8/42; C09K8/50; C09K8/504; C09K8/506; C09K8/508; C09K8/60; C09K8/80; H; H10; H10P; H10P74/00; H10P74/23
Claims Analysis
Total Claims: 34
Claim 1
Independent Claim
94 words
A method, in a computer, for determining an optimum process point for fabricating a device feature of a critical dimension, comprising: selecting a measuring point on a computer representation of a wafer corresponding to the feature of the critical dimension; calculating modeled behavior values and their rates of change over a range of corresponding values of a first process parameter representative of mask material edge position; selecting an optimum threshold value having the largest rate of change around said measuring point; and determining the first process parameter value corresponding to the optimum threshold value.
Claim 2
Independent Claim
94 words
A method, in a computer, for determining an optimum process point for fabricating a device feature of a critical dimension, comprising: selecting a measuring point on a computer representation of a wafer corresponding to the feature of the critical dimension; calculating modeled behavior values and their rates of change over a range of corresponding values of a first process parameter representative of mask material edge position; selecting an optimum threshold value having the largest rate of change around said measuring point; and determining the first process parameter value corresponding to the optimum threshold value.
Claim 3
Dependent Claim
36 words
The method of claim 1 , wherein calculating modeled behavior values comprises calculating the modeled behavior values and their rates of change over a range of corresponding values of the first process parameter representative of focus.
Claim 4
Dependent Claim
37 words
The method of claim 1 , wherein calculating modeled behavior values comprises calculating the modeled behavior values and their rates of change over a range of corresponding values of the first process parameter representative of numerical aperture.
Claim 5
Dependent Claim
59 words
The method of claim 1 , wherein calculating modeled behavior values comprises: selecting a point on one side of the measuring point; calculating a value of the modeled behavior at each of the points; and calculating a slope through each of the points, wherein the slope is a function of the values of the modeled behavior at each point.
Claim 6
Dependent Claim
17 words
The method of claim 4 , wherein calculating modeled behavior values further comprises selecting a second point.
Claim 7
Dependent Claim
103 words
The method of claim 1 , wherein calculating threshold values and their rates of change comprises: decrementing the value of the first process parameter; calculating the value of the modeled behavior at the measuring point; determining the value of the modeled behavior at a location offset from the measuring point in a first direction by a second value; determining the value of the modeled behavior at a location offset from the measuring point in a second direction, opposite to the first direction, by the second value; and calculating the rate of change of the modeled behavior corresponding to the first process parameter value.
Claim 8
Dependent Claim
44 words
The method of claim 6 , wherein calculating the rate of change comprises: calculating a difference of the modeled behavior values ascertained during determining the values of the modeled behavior; and dividing the difference of the modeled behavior values by twice the second value.
Claim 9
Independent Claim
115 words
A method, in a computer, for determining an optimum process point for fabricating a device feature of a critical dimension, comprising: selecting a measuring point on a computer representation of a wafer corresponding to the feature of the critical dimension; calculating modeled behavior values and their rates of change over a range of corresponding values of a first process parameter representative of mask material edge position; selecting an optimum threshold value having the largest rate of change around said measuring point; determining the first process parameter value corresponding to the optimum threshold value; and providing the optimum threshold value to a proximity effect correction process which modifies the mask pattern to compensate for proximity effects.
Claim 10
Independent Claim
115 words
A method, in a computer, for determining an optimum process point for fabricating a device feature of a critical dimension, comprising: selecting a measuring point on a computer representation of a wafer corresponding to the feature of the critical dimension; calculating modeled behavior values and their rates of change over a range of corresponding values of a first process parameter representative of mask material edge position; selecting an optimum threshold value having the largest rate of change around said measuring point; determining the first process parameter value corresponding to the optimum threshold value; and providing the optimum threshold value to a proximity effect correction process which modifies the mask pattern to compensate for proximity effects.
Claim 11
Dependent Claim
40 words
The method of claim 8 , wherein calculating modeled behavior values comprises calculating the modeled behavior values and their rates of change over a range of corresponding values of the first process parameter of a computer representation of a mask.
Claim 12
Dependent Claim
36 words
The method of claim 8 , wherein calculating modeled behavior values comprises calculating the modeled behavior values and their rates of change over a range of corresponding values of the first process parameter representative of focus.
Claim 13
Dependent Claim
37 words
The method of claim 8 , wherein calculating modeled behavior values comprises calculating the modeled behavior values and their rates of change over a range of corresponding values of the first process parameter representative of numerical aperture.
Claim 14
Independent Claim
74 words
A method, in a computer, for determining an optimum process point for fabricating a device feature of a critical dimension, comprising: selecting a measuring point on a computer representation of a wafer corresponding to the feature of the critical dimension; calculating modeled behavior values and their rates of change over a range of corresponding mask material edge positions; and selecting an optimum threshold value having the largest rate of change around said measuring point.
Claim 15
Independent Claim
74 words
A method, in a computer, for determining an optimum process point for fabricating a device feature of a critical dimension, comprising: selecting a measuring point on a computer representation of a wafer corresponding to the feature of the critical dimension; calculating modeled behavior values and their rates of change over a range of corresponding mask material edge positions; and selecting an optimum threshold value having the largest rate of change around said measuring point.
Claim 16
Dependent Claim
20 words
The method of claim 12 , further comprising determining the mask material edge position corresponding to the optimum threshold value.
Claim 17
Dependent Claim
64 words
The method of claim 12 , wherein calculating modeled behavior values and their rates of change comprises: selecting a point on one side of the measuring point; calculating a value of the modeled behavior at each of the points; and calculating a slope through each of the points, wherein the slope is a function of the values of the modeled behavior at each point.
Claim 18
Dependent Claim
107 words
The method of claim 12 , wherein calculating modeled behavior values and their rates of change further comprises: shifting the mask material edge position by a first value; calculating the value of the modeled behavior at the measuring point; determining the value of the modeled behavior at a location offset from the measuring point in a first direction by a second value; determining the value of the modeled behavior at a location offset from the measuring point in a second direction, opposite the first direction, by the second value; and calculating the rate of change of the modeled behavior value corresponding to the mask material edge position.
Claim 19
Dependent Claim
44 words
The method of claim 15 , wherein calculating the rate of change comprises: calculating a difference of the modeled behavior values ascertained during determining the values of the modeled behavior; and dividing the difference of the modeled behavior values by twice the second value.
Claim 20
Dependent Claim
31 words
The method of claim 15 , further comprising: providing the optimum threshold value to a proximity effect correction process which modifies the mask material edge position to compensate for proximity effects.
Claim 21
Independent Claim
206 words
A method, in a computer, for determining an optimum process point for fabricating a device feature of a critical dimension, comprising: selecting a measuring point on a computer representation of a wafer corresponding to the feature of the critical dimension; calculating modeled behavior values and their rates of change over a range of corresponding mask material edge positions, comprising: shifting the mask material edge position by a first value; calculating the value of the modeled behavior at the measuring point; determining the value of the modeled behavior at a location offset from the measuring point in a first direction by a second value; determining the value of the modeled behavior at a location offset from the measuring point in a second direction, opposite the first direction, by the second value; and calculating the rate of change of the threshold, comprising: calculating a difference of the modeled behavior values ascertained during determining the values of the modeled behavior; and dividing the difference of the modeled behavior values by twice the second value; selecting an optimum threshold value having the largest rate of change; and providing the optimum threshold value to a proximity effect correction process which modifies the mask material edge position to compensate for proximity effects.
Claim 22
Independent Claim
206 words
A method, in a computer, for determining an optimum process point for fabricating a device feature of a critical dimension, comprising: selecting a measuring point on a computer representation of a wafer corresponding to the feature of the critical dimension; calculating modeled behavior values and their rates of change over a range of corresponding mask material edge positions, comprising: shifting the mask material edge position by a first value; calculating the value of the modeled behavior at the measuring point; determining the value of the modeled behavior at a location offset from the measuring point in a first direction by a second value; determining the value of the modeled behavior at a location offset from the measuring point in a second direction, opposite the first direction, by the second value; and calculating the rate of change of the threshold, comprising: calculating a difference of the modeled behavior values ascertained during determining the values of the modeled behavior; and dividing the difference of the modeled behavior values by twice the second value; selecting an optimum threshold value having the largest rate of change; and providing the optimum threshold value to a proximity effect correction process which modifies the mask material edge position to compensate for proximity effects.
Claim 23
Independent Claim
121 words
A method, in a computer, for determining an optimum process point for fabricating a device feature of critical dimension, comprising: selecting a plurality of measuring points, wherein each measuring point corresponds to the feature of the critical dimension; calculating values and rates of change of modeled behavior over a range of values of a first process parameter for each measuring point, the range of values representative of mask material edge position; selecting an optimum threshold value having the largest rate of change for each measuring point; selecting a threshold value from the plurality of optimum threshold values; and providing the selected threshold value to a proximity effect correction process which modifies the mask material edge position to compensate for proximity effects.
Claim 24
Independent Claim
121 words
A method, in a computer, for determining an optimum process point for fabricating a device feature of critical dimension, comprising: selecting a plurality of measuring points, wherein each measuring point corresponds to the feature of the critical dimension; calculating values and rates of change of modeled behavior over a range of values of a first process parameter for each measuring point, the range of values representative of mask material edge position; selecting an optimum threshold value having the largest rate of change for each measuring point; selecting a threshold value from the plurality of optimum threshold values; and providing the selected threshold value to a proximity effect correction process which modifies the mask material edge position to compensate for proximity effects.
Claim 25
Dependent Claim
26 words
The method according to claim 19 , wherein selecting a threshold value includes determining the mean of the selected optimum threshold values for each measuring point.
Claim 26
Dependent Claim
26 words
The method according to claim 19 , wherein selecting a threshold value includes determining the median of the selected optimum threshold values for each measuring point.
Claim 27
Dependent Claim
127 words
A computer program product comprising a memory having computer program logic recorded thereon for enabling a processor in a computer system to determine an optimum process point for fabricating a device feature of a critical dimension, the computer program logic comprising: a first calculating process enabling the processor to calculate a modeled behavior value associated with the device feature and a rate of change of the modeled behavior value over a range of corresponding values of a first process parameter representative of mask material edge position; a second calculating process enabling the processor to select an optimum threshold value having the largest rate of change; and a determining process enabling the processor to determine the value of the first process parameter corresponding to the optimum threshold value.
Claim 28
Dependent Claim
127 words
A computer program product comprising a memory having computer program logic recorded thereon for enabling a processor in a computer system to determine an optimum process point for fabricating a device feature of a critical dimension, the computer program logic comprising: a first calculating process enabling the processor to calculate a modeled behavior value associated with the device feature and a rate of change of the modeled behavior value over a range of corresponding values of a first process parameter representative of mask material edge position; a second calculating process enabling the processor to select an optimum threshold value having the largest rate of change; and a determining process enabling the processor to determine the value of the first process parameter corresponding to the optimum threshold value.
Claim 29
Dependent Claim
38 words
The computer program product of claim 22 , further comprising: a providing process enabling the processor to provide the optimum threshold value to a proximity effect correction process which modifies the mask pattern to compensate for proximity effects.
Claim 30
Dependent Claim
46 words
The computer program according to claim 22 , wherein the first process parameter is a mask material edge position and the rate of change of the modeled behavior value indicates the process latitude in forming the device feature associated with a particular mask material edge position.
Claim 31
Dependent Claim
99 words
A computer system, comprising: a processor; a memory operatively coupled to the processor; a first calculating process enabling the processor to calculate a modeled behavior value associated with the device feature and a rate of change of the modeled behavior value over a range of corresponding values of a first process parameter representative of mask material edge positions; a second calculating process enabling the processor to select an optimum threshold value having the largest rate of change; and a determining process enabling the processor to determine the value of the first process parameter corresponding to the optimum threshold value.
Claim 32
Dependent Claim
99 words
A computer system, comprising: a processor; a memory operatively coupled to the processor; a first calculating process enabling the processor to calculate a modeled behavior value associated with the device feature and a rate of change of the modeled behavior value over a range of corresponding values of a first process parameter representative of mask material edge positions; a second calculating process enabling the processor to select an optimum threshold value having the largest rate of change; and a determining process enabling the processor to determine the value of the first process parameter corresponding to the optimum threshold value.
Claim 33
Dependent Claim
37 words
The computer system of claim 25 , further comprising a providing process enabling the processor to provide the optimum threshold value to a proximity effect correction process which modifies the mask pattern to compensate for proximity effects.
Claim 34
Dependent Claim
37 words
The computer system of claim 25 , wherein the first process parameter is a mask edge position and the rate of change of the modeled value indicates the process latitude of an edge of the device feature.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2004-01-23 | 2004-07-24 | 2005-01-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2008-01-23 | 2008-07-24 | 2009-01-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2012-01-23 | 2012-07-24 | 2013-01-23 | $7700.00 | Window Closed / Lapsed |