Process for selectively etching a layer of silicon dioxide on an underlying stop layer of silicon nitride

CAFC
  • US 5,286,344 A
  • Filed: 06/15/1992
  • Issued: 02/15/1994
  • Est. Priority Date: 06/15/1992
  • Status: Expired due to Term
First Claim
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1. A process for plasma etching a multilayer structure to form a predetermined etched pattern therein, comprising:

  • providing a multilayer structure, the outer layers of the multilayer structure comprising a silicon dioxide outer layer on an underlying silicon nitride stop layer;

    forming on the top surface of the multilayer structure a chemical etchant resistant layer having a pattern of openings in therein and thereby exposing areas of the silicon dioxide outer layer corresponding to the pattern of openings; and

    etching the exposed areas of the silicon dioxide outer layer to the silicon nitride stop layer, at a high SiO2 etch rate, and at a high level of selectivity of said SiO2 etch rate with respect to said Si3 N4 etch rate, with a fluorinated chemical etchant system including an etchant material ad an additive material, said additive material comprising a fluorocarbon material in which the number of hydrogen atoms is equal to or grater than the number of fluorine atoms, and sad etching step forming an etch pattern in the silicon dioxide outer layer in which the contact sidewalls of said SiO2 outer layer are perpendicular to the multilayer structure layers.

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