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Methods and apparatus for controlling plasma in a plasma processing system

  • US 10,032,605 B2
  • Filed: 07/06/2015
  • Issued: 07/24/2018
  • Est. Priority Date: 02/22/2012
  • Status: Active Grant
First Claim
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1. A method for processing a substrate, comprising:

  • controlling a base radio frequency (RF) generator to generate a base RF signal that pulses between a first base power level and a second base power level; and

    synchronizing a non-base RF generator with the base RF generator to generate a non-base RF signal that pulses between a first pre-determined non-base power level and a second pre-determined non-base power level,wherein to synchronize the pulsing of the non-base RF signal with the pulsing of the base RF signal, the non-base RF signal is pulsed to achieve the first pre-determined non-base power level simultaneous with achievement of the first base power level and to achieve the second pre-determined non-base power level simultaneous with achievement of the second base power level,wherein to synchronize the pulsing of the non-base RF signal with the pulsing of the base RF signal, both the base RF generator and the non-base RF generator are coupled to one and a same electrode of a plasma chamber via an impedance matching network and another electrode of the plasma chamber is coupled to a ground potential, wherein the other electrode faces the electrode, and the substrate is located over the electrode,wherein the first pre-determined non-base power level and the second pre-determined non-base power level are achieved during the processing of the substrate without detection of changes in plasma impedance during the processing of the substrate,wherein each of the first pre-determined non-base power level and the second pre-determined non-base power level is configured to reduce a change in the plasma impedance caused by said pulsing of the base RF signal.

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