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Impedance matching network and method

  • US 10,720,309 B1
  • Filed: 04/08/2020
  • Issued: 07/21/2020
  • Est. Priority Date: 07/10/2017
  • Status: Active Grant
First Claim
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1. A matching network comprising:

  • a) an RF input configured to operably couple to an RF source, the RF source configured to provide at least two repeating, non-zero pulse levels, the at least two pulse levels comprising a high-priority pulse level and a low-priority pulse level;

    b) an RF output configured to operably couple to a plasma chamber having a variable impedance; and

    c) at least one electronically variable capacitor (EVC), each EVC comprising discrete capacitors configured to switch in and out to vary a capacitance of the EVC and provide a plurality of match configurations for reducing a reflected power at an output of the RF source as the variable impedance of the plasma chamber changes;

    d) wherein each EVC of the at least one EVC has a switching limit comprising a predetermined number of switches in or out of the EVC'"'"'s discrete capacitors in a prior time interval of a predetermined time; and

    e) a control circuit configured to carry out the steps of;

    i) determining a parameter value related to the plasma chamber or the matching network;

    ii) determining a new match configuration for the at least one EVC based on the determined parameter value;

    iii) upon determining that switching the at least one EVC to the new match configuration would cause one or more of the at least one EVC to reach the switching limit, determining whether the new match configuration is for the low-priority pulse level or the high-priority pulse level;

    iv) upon determining in step iii) that the new match configuration is for the low-priority pulse level, preventing the switching of the at least one EVC to the new match configuration; and

    v) upon determining in step iii) that the new match configuration is for the high-priority pulse level, switching the at least one EVC to the new match configuration.

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