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METHOD AND APPARATUS FOR MEASURING ELECTRON DENSITY OF PLASMA AND PLASMA PROCESSING APPARATUS

  • US 20070284044A1
  • Filed: 05/01/2007
  • Published: 12/13/2007
  • Est. Priority Date: 04/24/2003
  • Status: Active Grant
First Claim
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1. An apparatus for monitoring plasma, comprising:

  • an insulating pipe inserted and attached into and to a chamber in or into which plasma is created or introduced;

    a coaxial cable provided with a probe portion formed by exposing a front core wire of the coaxial cable, and inserted into the insulating pipe from one end of the insulating pipe;

    an actuator for moving the coaxial cable in the insulating pipe in the axial direction thereof;

    a scalar reflection coefficient measuring unit for, while sweeping frequencies, transmitting electromagnetic signals of respective frequencies to the probe portion of the coaxial cable at certain power to be irradiated to a surrounding space, measuring reflection coefficients from the levels of signals reflected through the probe portion with respect to the respective frequencies, and obtaining frequency characteristics of the reflection coefficients; and

    a measurement operation unit for measuring a plasma absorption frequency based on a first frequency characteristic obtained by the reflection coefficient measuring unit in a state where the plasma does not exist in the chamber and a second frequency characteristic obtained by the reflection coefficient measuring unit in a state where plasma exists in the chamber, at a measurement location determined by a location of the probe portion.

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