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Method to recess cobalt for gate metal application

  • US 10,615,078 B2
  • Filed: 08/30/2019
  • Issued: 04/07/2020
  • Est. Priority Date: 03/09/2017
  • Status: Active Grant
First Claim
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1. A method of forming a semiconductor structure comprising:

  • forming a gate structure over a semiconductor material portion, wherein the gate structure comprises, from bottom to top, a gate dielectric, a gate electrode and a gate cap;

    forming a gate spacer on sidewalls of the gate structure;

    forming a source/drain region on each side of the gate structure;

    forming an interlevel dielectric (ILD) layer over each source/drain region and laterally surrounding the gate structure;

    patterning the ILD layer to form a contact opening, wherein the contact opening extends through the ILD layer and physically exposes a surface of the source/drain regions and the gate structure, and the patterning the ILD layer also recesses the gate cap and gate spacer exposed by the contact opening;

    forming a contact liner and a cobalt contact structure within the contact opening, wherein a portion of the contact liner and a portion of the cobalt contact structure are located above the recessed gate cap and recessed gate spacer;

    recessing the cobalt contact conductor to provide a cobalt contact conductor portion overlying the source/drain regions, wherein the recessing the cobalt contact conductor is performed by repeating steps of oxidizing the cobalt contact conductor to form a cobalt oxide layer on a surface of the cobalt contact conductor and removing the cobalt oxide layer; and

    recessing the contact liner to provide a contact liner portion contacting one of the source/drain regions.

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