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Optical emission spectroscopy (OES) for remote plasma monitoring

  • US 10,319,649 B2
  • Filed: 04/11/2017
  • Issued: 06/11/2019
  • Est. Priority Date: 04/11/2017
  • Status: Active Grant
First Claim
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1. A method of etching a substrate, the method comprising:

  • placing the substrate in a substrate processing region of a substrate processing chamber;

    flowing a fluorine-containing precursor into a remote plasma region separated from the substrate processing region by a showerhead;

    forming a remote plasma having a remote plasma power in the remote plasma region;

    producing plasma effluents from the fluorine-containing precursor in the remote plasma in the remote plasma region;

    flowing the plasma effluents through the showerhead into the substrate processing region;

    etching the substrate with the plasma effluents;

    forming a local plasma having a local plasma power in the substrate processing region while maintaining the remote plasma and etching the substrate, wherein the remote plasma power of the remote plasma exceeds the local plasma power of the local plasma by a factor of ten or more;

    acquiring an optical emission spectrum through a viewport affixed to a side of the substrate processing chamber and forming a border of the substrate processing region, wherein the optical emission spectrum represents intensity as a function of optical wavelength, and wherein the optical emission spectrum is acquired with an optical emission spectrometer;

    determining a fluorine signal from the optical emission spectrum; and

    determining an etch rate of the substrate based on the fluorine signal, wherein the fluorine signal is linearly correlated with the etch rate of the substrate.

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