Method and apparatus for optical emission end point detection in plasma etching processes
First Claim
1. An apparatus for determining the time at which a plasma etching process should be terminated, said process generating at least one discrete plasma species indicative of the progress of said process and a continuum plasma emission, comprising:
- means for monitoring the optical emission intensity of said plasma in a narrow band centered about a predetermined spectral line and generating a first signal indicative of the spectral intensity of said plasma species;
means for monitoring the optical emission intensity of said plasma in a wide band distinct from said narrow band and the emission spectral line of any discrete plasma species and generating a second signal indicative of the spectral intensity of only said continuum plasma emission; and
means for monitoring the magnitudes of said first and second signals and generating a termination signal when said magnitudes diverge, thereby indicating when said plasma etching process should be terminated.
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Abstract
An apparatus and method for determining the time at which a plasma etching process should be terminated. The process generates at least one etch product species and a continuum plasma emission. The apparatus monitors the optical emission intensity of the plasma in a narrow band centered about a predetermined spectral line and generates a first signal indicative of the spectral intensity of the etch product species. The apparatus further monitors the optical emission intensity of the plasma in a wide band and generates a second signal indicative of the spectral intensity of the continuum plasma emission. The apparatus further monitors the magnitudes of the first and second signals and generates a termination signal when the magnitudes diverge.
68 Citations
16 Claims
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1. An apparatus for determining the time at which a plasma etching process should be terminated, said process generating at least one discrete plasma species indicative of the progress of said process and a continuum plasma emission, comprising:
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means for monitoring the optical emission intensity of said plasma in a narrow band centered about a predetermined spectral line and generating a first signal indicative of the spectral intensity of said plasma species; means for monitoring the optical emission intensity of said plasma in a wide band distinct from said narrow band and the emission spectral line of any discrete plasma species and generating a second signal indicative of the spectral intensity of only said continuum plasma emission; and means for monitoring the magnitudes of said first and second signals and generating a termination signal when said magnitudes diverge, thereby indicating when said plasma etching process should be terminated. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method for determining the time at which a plasma etching process should be terminated, said process generating at least one discrete plasma species indicative of the progress of said process and a contniuum plasma emission, comprising:
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monitoring the optical emission intensity of said plasma in a narrow band centered about a predetermined spectral line and generating a first signal indicative of the spectral intensity of said plasma species; monitoring the optical emission intensity of said plasma in a wide band distinct from said narrow band and the emission spectral line of any discrete plasma species and generating a second signal indicative of the spectral intensity of only said continuum plasma emission; monitoring the magnitudes of said first and second signals and generating a termination signal when said magnitudes diverge; and indicating when said plasma etching process should be terminated in response to said termination signal. - View Dependent Claims (8, 9, 10, 11, 12)
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13. An apparatus for determining the time at which a plasma etching process should be terminated, said process generating at least one discrete plasma species and a continuum plasma emission, comprising:
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means for monitoring the optical emission intensity of said plasma in a wide band distinct from the emission spectral line of any discrete plasma species and generating a signal indicative of the spectral intensity of only said continuum plasma emission; and means for monitoring said intensity signal and generating a termination signal when the magnitude of said signal changes a predetermined magnitude, thereby indicating when said plasma etching process shall be terminated.
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14. An apparatus for determining the time at which a plasma etching process should be terminated, said process generating at least one plasma species indicative of the progress of said process comprising:
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means for monitoring the optical emission intensity of said plasma in a narrow band centered about a predetermined spectral line and generating a first signal indicative of the spectral intensity of said plasma species; means responsive to changes in an electrical property of said plasma for generating a second signal indicative thereof; and means for monitoring the magnitudes of said first and second signals and generating a termination signal when said magnitudes diverge, thereby indicating when said plasma etching process should be terminated. - View Dependent Claims (15, 16)
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Specification