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Forming epitaxial structures in fin field effect transistors

  • US 10,522,656 B2
  • Filed: 02/28/2018
  • Issued: 12/31/2019
  • Est. Priority Date: 02/28/2018
  • Status: Active Grant
First Claim
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1. A method, comprising:

  • forming a fin over a substrate;

    forming a gate structure over the fin;

    removing a portion of the fin adjacent to the gate structure to form a recess;

    forming a source/drain feature in the recess, wherein forming the source/drain feature includes;

    depositing a film including a first element in the recess, wherein the first element in a portion of the film penetrates bottom and sidewall surfaces of the recess to form a diffusion layer;

    removing a top portion of the film to expose the bottom and sidewall surfaces of the recess;

    thereafter, performing a first annealing process to the diffusion layer, thereby forming a first epitaxial layer;

    forming a second epitaxial layer over the first epitaxial layer, such that the second epitaxial layer is in contact with the bottom and sidewall surfaces of the recess; and

    forming a third epitaxial layer over the second epitaxial layer, wherein the second epitaxial layer and the third epitaxial layer include a second element different from the first element, and wherein both the first and the second elements are n-type dopants; and

    performing a second annealing process to the source/drain feature.

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