Semiconductor device
A semiconductor device is provided includes a substrate, a gate structure formed on the substrate, an epitaxial source/drain structure respectively formed at two sides of the gate structure, and a boron-rich interface layer. The boron-rich interface layer includes a bottom-and-sidewall portion and a top portion, and the epitaxial source/drain structure is enclosed by the bottom-and-sidewall portion and the top portion.
1. A semiconductor device comprising:
a substrate;
a gate structure formed on the substrate;
an epitaxial source/drain fin respectively formed at two sides of the gate structure; and
a boron-rich interface layer, the epitaxial source/drain structure being enclosed by the boron-rich interface layer, the boron-rich interface layer comprising a first portion and a second portion, the first portion being sandwiched in between the substrate and a bottom of the epitaxial source/drain fin, and a bottom width of the epitaxial source/drain fin being equal to or larger than a width of the boron-rich interface layer.
2. The semiconductor device according to claim 1 , wherein the epitaxial source/drain fin comprises silicon germanium (SiGe).
3. The semiconductor device according to claim 2 , wherein the epitaxial source/drain fin comprises a Ge concentration gradient increasing upwardly or a fixed Ge concentration.
4. The semiconductor device according to claim 1 , wherein the boron-rich interface layer further comprises SiGe.
5. The semiconductor device according to claim 1 , wherein the boron-rich interface layer comprises a boron concentration, and the boron concentration is between 1.0*10 21 atom/cm 3 and 3*10 21 atom/cm 3 .
6. The semiconductor device according to claim 1 , wherein the boron-rich interface layer comprises a thickness, and the thickness is between 10 angstroms (Å) and 100 Å.
7. The semiconductor device according to claim 1 , wherein the epitaxial source/drain fin is enclosed in the first portion and the second portion.
8. The semiconductor device according to claim 1 , wherein a boron concentration of the first portion is equal to or lower than a boron concentration of the second portion.
9. The semiconductor device according to claim 1 , wherein a thickness of the second portion is smaller than a thickness of the first portion.
10. The semiconductor device according to claim 1 , wherein a thickness of the second portion is the same with a thickness of the first portion.