VERTICAL FIELD-EFFECT-TRANSISTORS HAVING MULTIPLE THRESHOLD VOLTAGES
First Claim
1. A method for fabricating a semiconductor structure comprising a plurality of vertical transistors each having different threshold voltages, the method comprising:
- forming a structure comprising at least a substrate, a source contact layer on the substrate, a first spacer layer on the source contact layer, a replacement gate on the first spacer layer, a second spacer layer on the replacement gate, and an insulating layer on the second spacer layer;
forming a first trench in a first region of the structure, the first trench extending from a top surface of the insulating layer down to a top surface of the source contact layer;
epitaxially growing a first channel layer with a first doping concentration up from the top surface of the source contact layer, the first channel layer filling the first trench;
forming a second trench in a second region of the structure, the second trench extending from the top surface of the insulating layer down to the top surface of the source contact layer; and
epitaxially growing a second channel layer with a second doping concentration up from the top surface of the source contact layer, the second channel layer filling the second trench, where the second doping concentration is different from the first doping concentration.
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Abstract
Various embodiments disclose a method for fabricating a semiconductor structure including a plurality of vertical transistors each having different threshold voltages. In one embodiment the method includes forming a structure having at least a substrate, a source contact layer on the substrate, a first spacer layer on the source contact layer, a replacement gate on the first spacer layer, a second spacer layer on the replacement gate, and an insulating layer on the second spacer layer. A first trench is formed in a first region of the structure. A first channel layer having a first doping concentration is epitaxially grown in the first trench. A second trench is formed in a second region of the structure. A second channel layer having a second doping concentration is epitaxially grown in the second trench. The second doping concentration is different from the first doping concentration.
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Citations
20 Claims
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1. A method for fabricating a semiconductor structure comprising a plurality of vertical transistors each having different threshold voltages, the method comprising:
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forming a structure comprising at least a substrate, a source contact layer on the substrate, a first spacer layer on the source contact layer, a replacement gate on the first spacer layer, a second spacer layer on the replacement gate, and an insulating layer on the second spacer layer; forming a first trench in a first region of the structure, the first trench extending from a top surface of the insulating layer down to a top surface of the source contact layer; epitaxially growing a first channel layer with a first doping concentration up from the top surface of the source contact layer, the first channel layer filling the first trench; forming a second trench in a second region of the structure, the second trench extending from the top surface of the insulating layer down to the top surface of the source contact layer; and epitaxially growing a second channel layer with a second doping concentration up from the top surface of the source contact layer, the second channel layer filling the second trench, where the second doping concentration is different from the first doping concentration. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification