Patent ID: 9748386
Date: 2017-08-29
CPC Classifications: H01L

Claim:
1. An epitaxial structure of semiconductor device, comprising: a substrate; a recess in the substrate disposed near a surface of the substrate, wherein the recess has a recess depth; a first epitaxial layer disposed on surfaces of a sidewall and a bottom of the recess; a second epitaxial layer disposed on a surface of the first epitaxial layer, wherein a germanium (Ge) concentration of the second epitaxial layer is greater than a Ge concentration of the first epitaxial layer; and a third epitaxial layer disposed on a surface of the second epitaxial layer, wherein a Ge concentration of the third epitaxial layer is greater than the Ge concentration of the second epitaxial layer and a depth of the third epitaxial layer is about ½ to about ¾ of the recess depth.