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3D NAND STAIRCASE CD CONTROL BY USING INTERFEROMETRIC ENDPOINT DETECTION

  • US 20150011027A1
  • Filed: 07/08/2014
  • Published: 01/08/2015
  • Est. Priority Date: 07/08/2013
  • Status: Active Grant
First Claim
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1. A method of determining a photoresist trimming endpoint for forming stair-like structures on a substrate, comprising:

  • performing a trimming process on a substrate to trim a patterned photoresist layer disposed on a film stack from a first width to a second width in a processing chamber, wherein the patterned photoresist layer exposes a portion of the film stack uncovered by the patterned photoresist layer during the trimming process;

    directing an optical signal to a surface of the patterned photoresist layer while trimming the patterned photoresist layer;

    collecting a return reflected optical signal reflected from the photoresist layer; and

    determining a trimming endpoint by analyzing the return optical signal reflected from the photoresist layer.

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