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Ultra-thin resist and oxide/nitride hard mask for metal etch

  • US 6,171,763 B1
  • Filed: 12/02/1998
  • Issued: 01/09/2001
  • Est. Priority Date: 12/02/1998
  • Status: Expired due to Term
First Claim
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1. A method of forming a metal line, comprising:

  • providing a semiconductor substrate comprising a metal layer, a silicon nitride layer over the metal layer, and an oxide layer over the silicon nitride layer;

    depositing an ultra-thin photoresist over the oxide layer, the ultra-thin photoresist having a thickness less than about 2,000 Å

    ;

    irradiating the ultra-thin photoresist with electromagnetic radiation having a wavelength of about 250 nm or less;

    developing the ultra-thin photoresist exposing a portion of the oxide layer;

    etching the exposed portion of the an oxide layer exposing a portion of the silicon nitride layer with a first etch chemistry being oxide;

    photoresist selective;

    etching the exposed portion of the silicon nitride layer exposing a portion of the metal layer with a second etch chemistry being both silicon nitride;

    oxide selective and silicon nitride;

    metal selective; and

    etching the exposed portion of the metal layer with a third etch chemistry being metal;

    silicon nitride selective thereby forming the metal line.

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