Envelope follower end point detection in time division multiplexed processes
First Claim
1. A method for etching a feature in a substrate comprising the steps of:
- subjecting the substrate to an alternating cyclical process within a plasma chamber;
monitoring a variation in plasma emission intensity;
extracting an amplitude information from said plasma emission intensity using an envelope follower algorithm; and
discontinuing said alternating cyclical process at a time based on said monitoring step.
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Abstract
The present invention provides a method and an apparatus for establishing endpoint during an alternating cyclical etch process or time division multiplexed process. A substrate is placed within a plasma chamber and subjected to an alternating cyclical process having an etching step and a deposition step. A variation in plasma emission intensity is monitored using known optical emission spectrometry techniques. An amplitude information is extracted from a complex waveform of the plasma emission intensity using an envelope follower algorithm. The alternating cyclical process is discontinued when endpoint is reached at a time that is based on the monitoring step.
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Citations
47 Claims
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1. A method for etching a feature in a substrate comprising the steps of:
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subjecting the substrate to an alternating cyclical process within a plasma chamber; monitoring a variation in plasma emission intensity; extracting an amplitude information from said plasma emission intensity using an envelope follower algorithm; and discontinuing said alternating cyclical process at a time based on said monitoring step. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. A method of establishing endpoint during a time division multiplex process comprising the steps of:
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subjecting a substrate to the time division multiplex process; monitoring an attribute of a signal generated from the time division multiplex process; processing said attribute of the periodic signal generated from the time division multiplex process using an envelope follower; and discontinuing the time division multiplex process at a time based on the processing step. - View Dependent Claims (20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37)
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38. A method for establishing endpoint during a time division multiplexed process, the method comprising the steps of:
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a. etching a surface of a substrate in an etching step by contact with a reactive etching gas to removed material from the surface of the substrate and provide exposed surfaces; b. passivating the surface of the substrate in a passivating step during which the surfaces that were exposed in the preceding etching step are covered by a passivation layer thereby forming a temporary etching stop; c. alternatingly repeating the etching step and the passivating step; d. analyzing an intensity of at least one wavelength region of a plasma emission through the use of an envelope follower algorithm; and e. discontinuing the time division multiplexed process at a time which is dependent on said analysis step.
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39. A method of establishing endpoint during a time division multiplex process comprising the steps of:
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subjecting a substrate to the time division multiplex process; monitoring an attribute of a signal generated from the time division multiplex process; processing said attribute of the periodic signal generated from the time division multiplex process using a peak-hold and decay algorithm; and discontinuing the time division multiplex process at a time based on the processing step. - View Dependent Claims (40, 41, 42, 43, 44, 45, 46, 47)
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Specification