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Semiconductor structure with substitutional boron and method for fabrication thereof

  • US 8,999,861 B1
  • Filed: 05/11/2012
  • Issued: 04/07/2015
  • Est. Priority Date: 05/11/2011
  • Status: Active Grant
First Claim
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1. A method for fabricating a semiconductor structure on a semiconductor substrate, comprising:

  • masking portions of the substrate to form a pattern of transistors;

    performing a pre-amorphization implant into selected open areas defining a channel stack underlying a gate for a plurality of transistor elements of a similar type;

    performing a carbon ion implantation into the selected open areas in addition to the pre-amorphization implant;

    performing a boron ion implantation into the selected open areas in addition to the carbon ion implantation so as to form a screening region for the transistor element;

    performing a solid phase epitaxy after the carbon and boron ion implantations to cause the amorphized portions to transform into crystalline structures;

    performing an activation anneal to activate the boron by rendering the boron substitutional;

    forming a threshold voltage control layer on the boron screening region of the transistor element; and

    forming an epitaxial channel layer on the threshold control layer of the transistor element.

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