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Interferometric endpoint detection in a substrate etching process

  • US 6,905,624 B2
  • Filed: 07/07/2003
  • Issued: 06/14/2005
  • Est. Priority Date: 07/07/2003
  • Status: Expired due to Fees
First Claim
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1. A method of etching a substrate, the method comprising:

  • (a) placing a substrate in a process zone, the substrate comprising a material having a thickness;

    (b) introducing an etchant gas into the process zone;

    (c) energizing the etchant gas to etch the material; and

    (d) determining an endpoint of etching the material by (i) reflecting a light beam from the substrate, the light beam having a wavelength selected to have a coherence length in the substrate of from about 1.5 to about 4 times the thickness of the material, and (ii) detecting the reflected light beam to determine an endpoint of the substrate etching process.

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