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Method of anisotropic extraction of silicon nitride mandrel for fabrication of self-aligned block structures

  • US 10,446,405 B2
  • Filed: 02/23/2018
  • Issued: 10/15/2019
  • Est. Priority Date: 02/23/2017
  • Status: Active Grant
First Claim
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1. A method of preparing a self-aligned block (SAB) structure, comprising:

  • providing a substrate having raised features defined by a first material containing silicon nitride and a second material containing silicon oxide formed on first and second side walls of the first material in which the first and second side walls are spaced from each other in a lateral direction such that the first material is between the second material on the first and second side walls, and a third material spaced laterally from the first and second side walls of the first material and containing an organic material covering some of the raised features and exposing some raised features according to a block pattern formed in the third material;

    forming a first chemical mixture by plasma-excitation of a first process gas containing H and optionally a noble gas;

    exposing the first, second, and third materials on the substrate to the first chemical mixture such that after exposing to the first chemical mixture a depth within the first material is hydrogenated;

    thereafter, forming a second chemical mixture by plasma-excitation of a second process gas containing S, F, and optionally a noble element; and

    exposing the first, second, and third materials on the substrate to the second plasma-excited process gas to selectively etch the first material relative to the second and third materials and to remove the first material while the second and third materials remain after exposing to the second plasma-excited process gas.

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