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Monitoring a discharge in a plasma process

  • US 10,290,477 B2
  • Filed: 08/05/2016
  • Issued: 05/14/2019
  • Est. Priority Date: 02/07/2014
  • Status: Active Grant
First Claim
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1. A method of monitoring a discharge in a plasma process, the method comprising:

  • supplying a plasma process with a periodic power supply signal;

    determining a first power supply signal waveform in a first time interval within a first period of the power supply signal;

    determining a second power supply signal waveform in a second time interval within a second period of the power supply signal, wherein the second time interval is at a position within the second period corresponding to a position of the first time interval within the first period;

    comparing the second power supply signal waveform of the second time interval with a reference signal waveform associated with the first power supply signal waveform of the first time interval to thereby obtain a first comparison result;

    if the first comparison result corresponds to a given first comparison result, time-shifting one of the second power supply signal waveform and the reference signal waveform, and comparing the time-shifted signal waveform with the other one of the second power supply signal waveform and the reference signal waveform that was not time-shifted to thereby obtain a second comparison result; and

    generating an arc detection signal indicating an arc is present in the plasma process if the first comparison result corresponds to the first given comparison result and the second comparison result corresponds to a second given comparison result, respectively.

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