Patent ID: 8729607

Claim:
A semiconductor device comprising: a fin field effect transistor (finFET) structure, the finFET structure comprising: a silicon substrate; a first fin formed on the silicon substrate, wherein the first fin has a needle-shaped profile; wherein the first fin has a first part under a gate, and a second part, which is continuous with the first part; the second part having a cross-sectional shape different from the first part, and wherein the second part has the needle-shaped profile, and a portion of the first part, which is at an interface with the second part, and is exposed resulting from a difference between the first part and the second part in cross-sectional shape, is covered with the doped layer at a vicinity of a top of the needle-shaped profile of the first fin; a second fin formed on the silicon substrate, wherein the first fin and second fin are formed on the same side of the silicon substrate with a trough located between the first fin and the second fin; a buffer layer formed epitaxially on the first fin, the second fin and the trough located between the first fin and the second fin; and a doped layer formed epitaxially on the buffer layer, wherein the doped layer covers the first fin and the second fin, and an upper surface of the doped layer has a substantially flat profile.