Semiconductor device having epitaxial layer with planar surface and protrusions
A semiconductor device includes: a substrate; a gate structure on the substrate; and an epitaxial layer in the substrate adjacent to the gate structure, in which the epitaxial layer includes a planar surface and protrusions adjacent to two sides of the planar surface. Preferably, a contact plug is embedded in part of the epitaxial layer, and a silicide is disposed under the contact plug, in which a bottom surface of the silicide includes an arc.
1. A semiconductor device, comprising:
a substrate;
a gate structure on the substrate;
a spacer adjacent to the gate structure;
a contact plug adjacent to the gate structure; and
an epitaxial layer adjacent to the gate structure and under the contact plug, wherein the epitaxial layer comprises a planar surface and a protrusion, both the planar surface and the protrusion are adjacent to two sides of the contact plug, all of the planar surface is higher than a top surface of the substrate, and a tip of the protrusion is higher than the planar surface and contacting a sidewall of the spacer directly.
2. The semiconductor device of claim 1 , further comprising the contact plug embedded in part of the epitaxial layer, wherein a bottom surface of the contact plug comprises an arc.
3. The semiconductor device of claim 2 , further comprising a silicide under the contact plug.
4. The semiconductor device of claim 3 , wherein a bottom surface of the silicide comprises an arc.
5. The semiconductor device of claim 4 , wherein the epitaxial layer comprises silicon phosphide.
6. The semiconductor device of claim 1 , further comprising a contact etch stop layer (CESL) adjacent to the gate structure, wherein the protrusion contacts the CESL directly.
7. The semiconductor device of claim 1 , wherein a tip of the protrusion is higher than a top surface of the substrate.