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Biasing system for a plasma processing apparatus

  • US 10,290,475 B2
  • Filed: 09/24/2014
  • Issued: 05/14/2019
  • Est. Priority Date: 10/11/2012
  • Status: Active Grant
First Claim
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1. A plasma processing apparatus comprising:

  • a process chamber housing defining a process chamber;

    a platen positioned in the process chamber for supporting a workpiece;

    a source configured to generate a plasma in the process chamber;

    a controller;

    a gas inlet to introduce a first process gas into the process chamber during a first processing time interval;

    a cleaning gas, different than the first process gas, into the process chamber during a cleaning time interval and a second process gas into the process chamber during a conditioning time interval; and

    a biasing system, comprising a dual polarity DC power supply in communication with the controller and wherein the controller controls the biasing system to bias the platen with a negatively biased DC signal, comprising a plurality of consecutive negative pulses, to attract ions from the plasma towards the workpiece during the first processing time interval;

    to bias the platen with a first positively biased DC signal, comprising a plurality of consecutive positive pulses, to repel ions from the platen and form a plasma sheath proximate the process chamber walls so that the ions are accelerated towards interior surfaces of the process chamber housing during the cleaning time interval separate from the first processing time interval and occurring after the first processing time interval; and

    to bias the platen with a second positively biased DC signal having an amplitude less than the first positively biased DC signal, comprising a plurality of consecutive positive pulses during the conditioning time interval to treat the interior surfaces, wherein the controller is configured to stop a flow of the first process gas after the first processing time interval, to start a flow of the cleaning gas after the flow of the first process gas has been stopped, to stop the flow of the cleaning gas after the cleaning time interval, and to start the flow of the second process gas after the flow of cleaning gas has been stopped.

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