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Atomic layer etch process using an electron beam

  • US 9,520,294 B2
  • Filed: 10/02/2014
  • Issued: 12/13/2016
  • Est. Priority Date: 08/29/2014
  • Status: Active Grant
First Claim
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1. A method of removing an overlying film from a workpiece, comprising:

  • supporting the workpiece in a chamber;

    coupling an RF bias voltage to said workpiece;

    (A) performing a passivation process for a time duration corresponding to a desired thickness of a layer of said overlying film to be passivated, said passivation process comprising;

    introducing a passivation process gas into said chamber;

    generating a plasma in said chamber for passivation, by radiating gas in said chamber with an electron beam having a beam direction parallel to a plane of said workpiece from an electron beam generator;

    controlling said RF bias voltage to set energy of ions in said chamber to a first ion energy level less than a first minimum ion energy required for etching said overlying film;

    (B) performing an etching process by;

    introducing an etching process gas into said chamber;

    generating a plasma in said chamber for etching, by radiating gas in said chamber with an electron beam having a beam direction parallel to a plane of said workpiece from an electron beam generator;

    controlling said RF bias voltage to set energy of ions in said chamber to a second ion energy level exceeding said first minimum ion energy;

    wherein said controlling said RF bias voltage to set energy of ions to a first ion energy level comprises conforming a time domain waveform of said RF bias voltage to an RF waveform in which the RF voltage is at a level corresponding to said first ion energy level for a duration of about 50% of a continuous wave RF cycle of said RF waveform; and

    wherein said controlling said RF bias voltage to set energy of ions to a second ion energy level comprises conforming a time domain waveform of said RF bias voltage to an RF waveform in which the RF voltage is at a level corresponding to said second ion energy level for a duration of about 50% of a continuous wave RF cycle of said RF waveform.

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