Monitoring and controlling plasma processes via optical emission using principal component analysis
First Claim
1. 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, whereina fault in said etch process is detected when the result of said comparison exceeds said control limit.
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Accused Products
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.
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Citations
18 Claims
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1. 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:
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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. - View Dependent Claims (2, 3, 9, 10, 11, 12, 13)
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4. A method for monitoring an etch process in the course of manufacturing a semiconductor integrated circuit wafer comprising the steps:
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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. - View Dependent Claims (5, 6, 7, 8)
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14. 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:
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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. - View Dependent Claims (15, 16, 17, 18)
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Specification