Source and drain epitaxial layers
AssigneeTaiwan Semiconductor Manufacturing Company, Ltd.
InventorsWen-Hsien Tu, Chee-Wee Liu, Fang-Liang Lu
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Abstract
The present disclosure is directed to semiconductor structures with source/drain epitaxial stacks having a low-melting point top layer and a high-melting point bottom layer. For example, a semiconductor structure includes a gate structure disposed on a fin and a recess formed in a portion of the fin not covered by the gate structure. Further, the semiconductor structure includes a source/drain epitaxial stack disposed in the recess, where the source/drain epitaxial stack has bottom layer and a top layer with a higher activated dopant concentration than the bottom layer.
Claims20
A semiconductor structure, comprising:
- a fin disposed on a substrate, wherein the fin and the substrate comprise a semiconductor material;
- a gate structure disposed on the fin, wherein the gate structure wraps around a portion of a sidewall surface of the fin;
- a recess formed in a portion of the fin adjacent to the gate structure;
- a source/drain epitaxial stack disposed in the recess, wherein a difference between a dopant concentration of the source/drain epitaxial stack and a carrier concentration of the source/drain epitaxial stack increases in a vertical direction towards the substrate;
- and
- a contact disposed on a top layer of the source/drain epitaxial stack, wherein the contact is adjacent to the gate structure.
A structure, comprising:
- a fin on a substrate, the fin having a recessed portion;
- a gate structure on the fin, wherein the gate structure wraps around a portion of a top surface of the fin and a portion of a sidewall surface of the fin;
- a source/drain epitaxial stack in the recessed portion of the fin, the source/drain epitaxial stack comprising:
- a bottom layer having a crystalline microstructure;
- and
- a top layer disposed on the bottom layer, wherein a roughness of an interface between the top layer and the bottom layer is greater than a roughness of a top surface of the top layer.
A structure, comprising:
- a fin on a substrate, the fin having recessed portions and non-recessed portions;
- a gate structure covering the non-recessed portions;
- and
- a source/drain epitaxial stack on recessed portions, the source/drain epitaxial stack comprising:
- a first layer having a first activated carrier concentration less than a chemical dopant concentration of the first layer;
- and
- a second layer disposed on the first layer, the second layer having a second activated carrier concentration substantially equal to a chemical dopant concentration of the second layer.
Dependencies are inferred from the claim text.