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Controlling the shape of source/drain regions in FinFETs

  • US 8,975,144 B2
  • Filed: 11/30/2012
  • Issued: 03/10/2015
  • Est. Priority Date: 09/29/2009
  • Status: Active Grant
First Claim
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1. A method comprising:

  • forming a fin field-effect transistor (FinFET) comprising;

    forming a semiconductor fin over and adjacent insulation regions, wherein the;

    forming a gate dielectric on a top surface, and extending on sidewalls, of the semiconductor fin;

    forming a gate electrode on the gate dielectric; and

    forming a source/drain region over the insulation regions and adjoining the semiconductor fin, wherein the forming the source/drain region comprises;

    forming a first semiconductor region comprising silicon and an element selected from the group consisting of germanium and carbon, wherein the element has a first atomic percentage in the first semiconductor region, and wherein the first semiconductor region comprises an up-slant facet and a down-slant facet; and

    forming a second semiconductor region comprising silicon and the element, wherein the element has a second atomic percentage in the second semiconductor region with the second atomic percentage being lower than the first atomic percentage, wherein the second semiconductor region comprises a first portion on the up-slant facet and having a first thickness, and wherein a second portion of the second semiconductor region on the down-slant facet has a second thickness smaller than the first thickness.

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