Method and apparatus for monitoring plasma chamber condition by observing plasma stability
First Claim
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1. A method of monitoring plasma chamber condition of a plasma process, the method comprising:
- detecting an intensity of a predetermined wavelength of radiation produced by the plasma process to electrically generate an output signal;
generating a parameter representing a change rate of the output signal;
comparing the parameter to a predetermined threshold, said parameter comprising a velocity value representing the change rate of the output signal and an acceleration value representing a change rate of the velocity value; and
indicating an abnormal condition when the parameter exceeds the predetermined threshold.
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Abstract
A method and apparatus for monitoring condition of the plasma of a plasma process during processing is disclosed. A spectrum detector (12) detects the intensity of a predetermined wavelength of radiation produced by the plasma process. The output of the spectrum detector is sampled, filtered, and normalized. A parameter calculator (20) calculates a parameter such as velocity or acceleration of the intensity. The calculated parameter is compared to a predetermined threshold. If the parameter exceeds the predetermined threshold, an error condition is indicated.
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Citations
20 Claims
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1. A method of monitoring plasma chamber condition of a plasma process, the method comprising:
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detecting an intensity of a predetermined wavelength of radiation produced by the plasma process to electrically generate an output signal; generating a parameter representing a change rate of the output signal; comparing the parameter to a predetermined threshold, said parameter comprising a velocity value representing the change rate of the output signal and an acceleration value representing a change rate of the velocity value; and indicating an abnormal condition when the parameter exceeds the predetermined threshold. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method of monitoring chamber condition of a plasma process, the method comprising:
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detecting an intensity of a predetermined wavelength of radiation produced by the plasma process to electrically generate an output signal; sampling the output signal to generate a digital signal representing the output signal; filtering the digital signal to reduce noise, thereby generating a filtered signal; normalizing the filtered signal to reduce signal decade, thereby generating a normalized signal; generating a parameter representing a change rate of the normalized signal, said parameter comprising a velocity value representing the change rate of the normalized signal and an acceleration value representing the change rate of the velocity value; comparing said parameter to a predetermined threshold; and indicating an abnormal condition when the parameter exceeds the predetermined threshold. - View Dependent Claims (10)
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11. An apparatus for monitoring chamber condition of a plasma process, the apparatus comprising:
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a plasma chamber for performing the plasma process, the plasma process producing radiation having an intensity and a predetermined wavelength; means for detecting the intensity of the predetermined wavelength of radiation and for electrically generating an output signal; means for generating a parameter representing a change rate of the output signal; means for comparing the parameter with a predetermined threshold, said parameter comprising a velocity value representing the change rate of the output signal and an acceleration value representing the change rate of the velocity value; and an indicator that indicates an abnormal condition when the parameter exceeds the predetermined threshold. - View Dependent Claims (12, 13, 14, 15)
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16. An apparatus for monitoring plasma chamber condition of a plasma process, the apparatus comprising:
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a plasma chamber for performing the plasma process, the plasma process producing radiation having an intensity and a predetermined wavelength; a spectrum detector coupled to the plasma chamber, the spectrum detector detecting the intensity of the predetermined wavelength of radiation and electrically generating an output signal; an analog-to-digital converter coupled to receive the output signal, the analog-to-digital converter generating a digital signal representing the output signal; a filter coupled to the analog-to-digital converter, the filter filtering the digital signal to reduce noise, the filter generating a filtered signal; a normalizer coupled to the filter, the normalizer normalizing the filtered signal to reduce signal decay, the normalizer generating a normalized signal; a parameter calculator coupled to the normalizer, the parameter calculator generating a parameter representing a change rate of the normalized signal, said parameter comprising a velocity value representing the change rate of the output signal and an acceleration value representing the change rate of the velocity value; and a comparator coupled to the parameter calculator, the comparator comparing the parameter to a predetermined threshold, an abnormal condition being determined when the parameter exceeds the predetermined threshold. - View Dependent Claims (17)
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18. A method of monitoring plasma chamber condition of a plasma process, the method comprising:
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detecting an intensity of a predetermined wavelength of radiation produced by the plasma process to electrically generate an output signal; sampling the output signal to generate a digital signal; filtering the digital signal to reduce noise and generate a filtered signal by averaging the digital signal; generating a parameter representing a change rate of the output signal; comparing the parameter to a predetermined threshold; and indicating an abnormal condition when the parameter exceeds the predetermined threshold. - View Dependent Claims (19, 20)
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Specification