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US5355306A
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Alignment system and method of alignment by symmetrical and asymmetrical analysis
Assignee: NXP USA Inc
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Filing: 1993-09-30
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Granted: 1994-10-11
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Expires: 2013-09-30
Abstract
Abstract An alignment signal is analyzed asymmetrically using any means of artificial intelligence or similar logic to apply empirical or theoretical offsets to signal position calculations based on the unique signal shapes of the different signals collected. A database of signal shapes and correlated offsets is used to improve subsequent alignment steps. For example, a case-based reasoning method can be used.
Inventors
- 👤 Whitson G. Waldo, III
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 23:47
CPC Classifications
G; G03; G03F; G03F9/00; G03F9/70; G05; G05B; G05B19/00; G05B19/02; G05B19/18; G05B19/402; G05B2219/00; G05B2219/30; G05B2219/33; G05B2219/33002; G05B2219/45; G05B2219/45028; G05B2219/49; G05B2219/49115
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
88 words
A method of alignment, comprising the steps of: providing a lithographic tool; illuminating a target with a light generated from the lithographic tool; collecting an amount of light diffracted off the target to obtain a signal having positional information about the target; processing the signal to obtain a symmetrical analysis of the signal; processing the signal to obtain an asymmetrical analysis of the signal; calculating a correction based on a combination of the symmetrical analysis and the asymmetrical analysis; and actuating the lithographic tool according to the correction.
Claim 2
Independent Claim
88 words
A method of alignment, comprising the steps of: providing a lithographic tool; illuminating a target with a light generated from the lithographic tool; collecting an amount of light diffracted off the target to obtain a signal having positional information about the target; processing the signal to obtain a symmetrical analysis of the signal; processing the signal to obtain an asymmetrical analysis of the signal; calculating a correction based on a combination of the symmetrical analysis and the asymmetrical analysis; and actuating the lithographic tool according to the correction.
Claim 3
Dependent Claim
88 words
The method of claim 1 wherein the step of processing the signal to obtain an asymmetrical analysis of the signal further comprises the steps of: creating a library having a plurality of library signals, each having a correlated offset; matching the signal with a closest match to one of the plurality of library signals; applying the correlated offset of the library signal to the signal; and adding the signal and the correlated offset to the library if it is different than any of the plurality of library signals.
Claim 4
Dependent Claim
41 words
The method of claim 2 further comprising the step of: interpolating between a number of most closely matched of the plurality library signals when an exact match between the signal and one of the plurality of library signals is not found.
Claim 5
Dependent Claim
33 words
The method of claim 1 wherein the step of processing the signal to obtain an asymmetrical analysis of the signal further comprises the steps of: utilizing a mathematical expression for the signal shape.
Claim 6
Dependent Claim
46 words
The method of claim 1 wherein the step of processing the signal to obtain an asymmetrical analysis of the signal further comprises the steps of: utilizing a system to identify the signal by Fourier transform, Fourier component analysis, power spectrum density description, or threshold centroid signature.
Claim 7
Dependent Claim
35 words
The method of claim 1 wherein the step of processing the signal to obtain an asymmetrical analysis of the signal further comprises the steps of: obtaining the asymmetrical analysis of the signal by artificial intelligence.
Claim 8
Dependent Claim
45 words
The method of claim 1 wherein the step of processing the signal to obtain an asymmetrical analysis of the signal further comprises the steps of: providing information related to at least one previous signal; utilizing the information to obtain the asymmetrical analysis of the signal.
Claim 9
Independent Claim
79 words
A method of alignment, comprising the steps of: providing a lithographic tool; illuminating a target with a light generated from the lithographic tool; collecting an amount of light diffracted off the target to obtain a signal having positional information about the target; symmetrically processing the signal; asymmetrically processing the signal by using a case-based method; calculating a correction based on a combination of the symmetrical processing and the asymmetrical processing; and actuating the lithographic tool according to the correction.
Claim 10
Independent Claim
79 words
A method of alignment, comprising the steps of: providing a lithographic tool; illuminating a target with a light generated from the lithographic tool; collecting an amount of light diffracted off the target to obtain a signal having positional information about the target; symmetrically processing the signal; asymmetrically processing the signal by using a case-based method; calculating a correction based on a combination of the symmetrical processing and the asymmetrical processing; and actuating the lithographic tool according to the correction.
Claim 11
Dependent Claim
86 words
The method of claim 8 wherein the step of asymmetrically processing the signal by using a casebased method further comprises the steps of: creating a library having a plurality of library signals, each having a correlated offset; matching the signal with a closest match to one of the plurality of library signals; applying the correlated offset of the library signal to the signal; and adding the signal and the correlated offset to the library if it is different than any of the plurality of library signals.
Claim 12
Dependent Claim
41 words
The method of claim 9 further comprising the step of: interpolating between a number of most closely matched of the plurality library signals when an exact match between the signal and one of the plurality of library signals is not found.
Claim 13
Dependent Claim
82 words
An alignment system, comprising: a lithographic tool; a means for processing a signal to obtain a symmetrical analysis of the signal coupled to the lithographic tool; a means for processing the signal to obtain an asymmetrical analysis of the signal coupled to the lithographic tool; a means for calculating a total correction based on a combination of the symmetrical analysis and the asymmetrical analysis coupled to the lithographic tool; and a means for actuating the lithographic tool according to the total correction.
Claim 14
Dependent Claim
82 words
An alignment system, comprising: a lithographic tool; a means for processing a signal to obtain a symmetrical analysis of the signal coupled to the lithographic tool; a means for processing the signal to obtain an asymmetrical analysis of the signal coupled to the lithographic tool; a means for calculating a total correction based on a combination of the symmetrical analysis and the asymmetrical analysis coupled to the lithographic tool; and a means for actuating the lithographic tool according to the total correction.
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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) | 1997-10-10 | 1998-04-11 | 1998-10-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-10-10 | 2002-04-11 | 2002-10-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-10-10 | 2006-04-11 | 2006-10-11 | $7700.00 | Window Closed / Lapsed |