US5658423A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Monitoring and controlling plasma processes via optical emission using principal component analysis
Assignee: International Business Machines Corp
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Filing: 1995-11-27
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Granted: 1997-08-19
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Expires: 2015-11-27
Abstract
Abstract A method of monitoring the status of plasma in a chamber using real-time spectral data while conducting an etch process during the course of manufacturing of semiconductor wafers. Spectral data is collected during etching, with the spectral data characterizing an emission of light from etch species contained in the plasma, and maintaining the collected data as reference data. A model of principal components of the data is generated. Additional spectral data is extracted from the plasma and compared with the model. Discrepancies pinpoint the presence of foreign material faults and help determine the cause of the failures to ensure appropriate corrective action.
Inventors
- 👤 David Angell
- 👤 Paul Bao-Luo Chou
- 👤 Antonio Rogelio Lee
- 👤 Martin Clarence Sturzenbecker
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 16:04
CPC Classifications
H; H01; H01J; H01J37/00; H01J37/32; H01J37/32009; H01J37/32082; H01J37/32174; H01J37/32431; H01J37/32917; H01J37/32935; H01J37/32963; H01J37/32972; H01J37/3299; H01J2237/00; H01J2237/32; H01J2237/33; H01J2237/334
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
139 words
A method for monitoring the status of a plasma using real-time spectral data obtained while conducting an etch process in the course of manufacturing a semiconductor wafer, said method comprising the steps of: a) collecting said spectral data during said etch process from said plasma; b) calculating principal components of said collected spectral data and determining a control limit characteristic of said etch process; c) extracting from said plasma additional spectral data; d) forwardly, and subsequently backwardly projecting said forwardly projected additional spectral data utilizing said principal components; e) subtracting said additional spectral data from said backwardly projected data, resulting in a data set of residuals; and f) combining said residuals and comparing said combined residuals to said control limits, wherein a fault in said etch process is detected when the result of said comparison exceeds said control limit.
Claim 2
Independent Claim
139 words
A method for monitoring the status of a plasma using real-time spectral data obtained while conducting an etch process in the course of manufacturing a semiconductor wafer, said method comprising the steps of: a) collecting said spectral data during said etch process from said plasma; b) calculating principal components of said collected spectral data and determining a control limit characteristic of said etch process; c) extracting from said plasma additional spectral data; d) forwardly, and subsequently backwardly projecting said forwardly projected additional spectral data utilizing said principal components; e) subtracting said additional spectral data from said backwardly projected data, resulting in a data set of residuals; and f) combining said residuals and comparing said combined residuals to said control limits, wherein a fault in said etch process is detected when the result of said comparison exceeds said control limit.
Claim 3
Dependent Claim
26 words
The method as recited in step b) of claim 1, wherein said principal components characterize the relative importance of etch species contained in said spectral data.
Claim 4
Dependent Claim
26 words
The method as recited in step b) of claim 1, further comprising the step of calculating a percentage variation of selected samples of said spectral data.
Claim 5
Independent Claim
166 words
A method for monitoring an etch process in the course of manufacturing a semiconductor integrated circuit wafer comprising the steps: loading the wafer into a etch chamber; filling said chamber with etch gases in a controlled environment; igniting said etch gases by applying RF-power to said gases, thereby establishing a plasma within said chamber; simultaneously collecting spectral data, wherein said collected data constitutes a reference data set; generating principal components from said reference data set; determining, with said reference data, a process control limit that defines, a safe operating window for said etch process; subsequently, collecting from said plasma additional spectral data; forwardly, and subsequently backwardly projecting said forwardly projected additional spectral data utilizing said principal components; subtracting said additional spectral data from said backwardly projected data, resulting in a data set of residuals; and combining said residuals and comparing said combined residuals to said control limit, wherein a fault in said etch process is detected when the result of said comparison exceeds said control limit.
Claim 6
Independent Claim
166 words
A method for monitoring an etch process in the course of manufacturing a semiconductor integrated circuit wafer comprising the steps: loading the wafer into a etch chamber; filling said chamber with etch gases in a controlled environment; igniting said etch gases by applying RF-power to said gases, thereby establishing a plasma within said chamber; simultaneously collecting spectral data, wherein said collected data constitutes a reference data set; generating principal components from said reference data set; determining, with said reference data, a process control limit that defines, a safe operating window for said etch process; subsequently, collecting from said plasma additional spectral data; forwardly, and subsequently backwardly projecting said forwardly projected additional spectral data utilizing said principal components; subtracting said additional spectral data from said backwardly projected data, resulting in a data set of residuals; and combining said residuals and comparing said combined residuals to said control limit, wherein a fault in said etch process is detected when the result of said comparison exceeds said control limit.
Claim 7
Dependent Claim
36 words
The method as recited in claim 4, wherein said fault in said process is characterized by a value defining an intensity of an emission of light from species not originally contained in said reference data set.
Claim 8
Independent Claim
39 words
The method as recited in claims 4, wherein said fault in said process is characterized by a value defining an intensity of an emission of light from species originally contained in said reference data set but having different ratios.
Claim 9
Dependent Claim
47 words
The method as recited in claim 4, wherein said fault in said process is characterized by a value defining an intensity of said emission of light from species originally contained in said reference data set and having a same ratios, but wherein said ratio changes over time.
Claim 10
Dependent Claim
65 words
The method as recited in claim 4, wherein said faults in said etch process are selected from a group that consists of a presence of foreign material, a prior processing step that was misprocessed, a faulty mass flow controller, a leaky chamber, a poorly calibrated chamber control sensor, chamber wall conditioning, processing of a wrong wafer in said chamber, and replicating a previous etch process.
Claim 11
Dependent Claim
18 words
The method as recited in step a) of claim 1, wherein said collected data represents reference spectral data.
Claim 12
Dependent Claim
28 words
The method as recited in claim 9, wherein discrepancies between said reference spectral data and said additional spectral data pinpoints the presence of said fault in said process.
Claim 13
Dependent Claim
22 words
The method as recited in step b) of claim 1, further comprising the step of generating a model, utilizing said spectral data.
Claim 14
Dependent Claim
20 words
The method as recited in claim 1, wherein said spectral data characterizes an emission of light generated within said plasma.
Claim 15
Dependent Claim
26 words
The method as recited in step d) of claim 1, wherein said forwardly and backwardly projection of said additional spectral data is achieved by matrix multiplication.
Claim 16
Independent Claim
139 words
A method for monitoring the status of a plasma using real-time spectral data obtained while conducting an etch process, said method comprising the steps of: a) collecting said real-time spectral data from said plasma; b) calculating principal components of said collected spectral data and a control limit indicative of said etch process; c) while further conducting said etch process, collecting new spectral data from said plasma; d) forward projecting said new spectral data utilizing said principal components; e) backwardly projecting said forwardly projected data, utilizing said principal components; f) calculating residuals by subtracting said new spectral data from said backwardly projected data; g) combining said residuals, resulting in a residual value; and h) comparing said resultant residual value to said control limit, wherein the result of said comparison exceeding said control limit constitutes a fault in said etch process.
Claim 17
Independent Claim
139 words
A method for monitoring the status of a plasma using real-time spectral data obtained while conducting an etch process, said method comprising the steps of: a) collecting said real-time spectral data from said plasma; b) calculating principal components of said collected spectral data and a control limit indicative of said etch process; c) while further conducting said etch process, collecting new spectral data from said plasma; d) forward projecting said new spectral data utilizing said principal components; e) backwardly projecting said forwardly projected data, utilizing said principal components; f) calculating residuals by subtracting said new spectral data from said backwardly projected data; g) combining said residuals, resulting in a residual value; and h) comparing said resultant residual value to said control limit, wherein the result of said comparison exceeding said control limit constitutes a fault in said etch process.
Claim 18
Dependent Claim
29 words
The method as recited in step b) of claim 14, wherein said principal components characterize the relative importance of each etch specie contained in said real time spectral data.
Claim 19
Dependent Claim
27 words
The method as recited in step b) of claim 14, further comprising the step of calculating a percentage variation of selected samples of said new spectral data.
Claim 20
Dependent Claim
18 words
The method as recited in step g) of claim 14, wherein combining said residuals includes adding said residuals.
Claim 21
Dependent Claim
28 words
The method as recited in step g) of claim 14, wherein combining said residuals includes taking the square root of the difference of the squares of said residuals.
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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) | 2000-08-18 | 2001-02-17 | 2001-08-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2004-08-18 | 2005-02-17 | 2005-08-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2008-08-18 | 2009-02-17 | 2009-08-19 | $7700.00 | Window Closed / Lapsed |