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Controlling plasma processing using parameters derived through the use of a planar ion flux probing arrangement

  • US 7,413,672 B1
  • Filed: 04/04/2006
  • Issued: 08/19/2008
  • Est. Priority Date: 04/04/2006
  • Status: Active Grant
First Claim
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1. A method for controlling a substrate processing process, said substrate processing process being configured to process a substrate using plasma in a substrate processing chamber, comprising:

  • providing a PIF (planar ion flux) measurement arrangement, said PIF measurement arrangement including at least a PIF probe that has a surface exposed to a plasma sheath of said plasma while said substrate is processed by said plasma;

    alternately creating a charging phase and a quiescent phase for said PIF arrangement using an energy source that is configured to provide energy to said plasma via said PIF probe;

    ascertaining a time tpoint2, said time tpoint2 representing a time during said charging phase of said PIF measurement arrangement wherein a first potential difference across said plasma sheath equals to a plasma potential of said plasma;

    ascertaining a time tpoint3a, said time tpoint3a representing a time during said charging phase of said PIF measurement arrangement wherein a second potential difference across said plasma sheath equals a floating potential, said floating potential representing a value of a potential difference across said plasma sheath during said charging phase when no current flows through said PIF probe; and

    generating a control signal to create at least one of an alarm and a transition in said substrate processing process if a time difference between said time tpoint2 and said time tpoint3a meets a predefined condition.

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