Method and device for detecting the end point of plasma process
First Claim
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1. An end point detection method comprising the steps of:
- sequentially detecting, when a process using a plasma is performed for an object to be processed, emission spectra in two specific wavelength bands of two active species in the plasma by using a photodetecting means;
obtaining an average value of emission intensities for each of the emission spectra during a time period;
making two graphs, each showing the relationship between said average value and time, substantially equal to each other in inclination;
calculating a ratio or a difference between the two graphs to obtain a coefficient;
obtaining a calculated value using the coefficient and a newly obtained emission intensity; and
determining a point at which said calculated value exceeds a reference value as an end point of the process.
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Abstract
This invention provides an end point detection method including the steps of sequentially detecting, when a process using a plasma is performed for an object to be processed, emission spectra in a specific wavelength band of an active species in the plasma by using a photodetector, calculating sum average values of emission intensities of the emission spectra, calculating the ratio or the difference between the sum average values to obtain a calculated value, and determining a point at which the calculated value exceeds a predetermined reference value as an end point of the process.
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Citations
14 Claims
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1. An end point detection method comprising the steps of:
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sequentially detecting, when a process using a plasma is performed for an object to be processed, emission spectra in two specific wavelength bands of two active species in the plasma by using a photodetecting means; obtaining an average value of emission intensities for each of the emission spectra during a time period; making two graphs, each showing the relationship between said average value and time, substantially equal to each other in inclination; calculating a ratio or a difference between the two graphs to obtain a coefficient; obtaining a calculated value using the coefficient and a newly obtained emission intensity; and determining a point at which said calculated value exceeds a reference value as an end point of the process. - View Dependent Claims (2, 3, 4, 5)
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6. An end point detection method comprising the steps of:
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sequentially detecting, when a process using a plasma is performed for an object to be processed, an emission spectrum in a specific wavelength band of at least one first active species and a peak value of an emission intensity of at least one second active species in the plasma by using photodetecting means; obtaining an average value of an emission intensity of the emission spectrum during a time period; making two graphs, each showing the relationship between said average value and time and the relationship between said peak value and time, substantially equal to each other in inclination; calculating a ratio or a difference between the peak value of the emission intensity and said average value to obtain a coefficient; obtaining a calculated value using the coefficient and a newly obtained emission intensity; and determining a point at which the calculated value exceeds a reference value as an end point of the process. - View Dependent Claims (7, 8, 9, 10, 11)
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12. An end point detection apparatus comprising:
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an average value calculating means for calculating average values of emission intensities of emission spectra obtained by detecting, by using photodetecting means, the emission spectra generated in two specific wavelength bands when a process using a plasma is performed for an object to be processed; calculating means for calculating a ratio or a difference between average values, to obtain a calculated value; means for making two graphs, each showing a relationship between said average value and time, made substantially equal to each other in inclination; and determining means for determining a point at which the calculated value exceeds a reference value as an end point of the process.
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13. A plasma process apparatus for applying a process using a plasma to an object, comprising:
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a pair of electrodes arranged in a process chamber, an object to be processed being placed on one of said electrodes, and a high frequency power being applied therebetween to convert a process gas into a plasma; light-condensing means for condensing light emitted from the plasma in said process chamber; photodetecting means for detecting emission spectra in two specific wavelength bands from the light condensed by said light-condensing means; average value calculating means for calculating average values of emission intensities for each of the emission spectra on the basis of information from said photodetecting means; calculating means for calculating a ratio or a difference between average values, to obtain a calculated value; means for making two graphs, each showing a relationship between said average value and time, made substantially equal to each other in inclination; and determining means for determining a point at which the calculated value exceeds a reference value as an end point of the process. - View Dependent Claims (14)
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Specification