Semiconductor device and method for fabricating the same
A method for fabricating a semiconductor device is disclosed. A fin is formed on a substrate. The fin protrudes from a trench isolation layer on a substrate. The fin comprises a source region, a drain region and a channel region therebetween. A dummy gate strides across the fin and surrounding the channel region. An upper portion of the fin is removed so as to form a hollow channel underneath the dummy gate. A replacement channel layer is in-situ epitaxially grown in the hollow channel.
1. A semiconductor device, comprising:
a bulk semiconductor substrate;
a fin on the bulk semiconductor substrate, the fin comprising a source region, a drain region and a channel region therebetween;
a replacement channel layer disposed in the channel region;
a gate striding across the fin and surrounding the replacement channel layer;
an epitaxial source layer in the source region; and
an epitaxial drain layer in the drain region, wherein the epitaxial source layer and the epitaxial drain layer are contiguous with the replacement channel layer, and wherein a bottom surface of the epitaxial source layer and the epitaxial drain layer is shallower than a bottom surface of the replacement channel layer.
2. The semiconductor device according to claim 1 , wherein the replacement channel layer comprises a SiGe layer.
3. The semiconductor device according to claim 2 , wherein the SiGe layer is an un-doped SiGe layer.
4. The semiconductor device according to claim 1 , wherein the thickness of the replacement channel layer ranges between 400˜600 angstroms.
5. The semiconductor device according to claim 4 , wherein the thickness of the replacement channel layer is uniform between the source region and the drain region.
6. The semiconductor device according to claim 1 , wherein the semiconductor device is a PMOS finFET device, and wherein the epitaxial source layer and the epitaxial drain layer are boron-doped SiGe epitaxial layers.
7. The semiconductor device according to claim 1 further comprising a gate dielectric layer between the gate and the replacement channel layer, and wherein the gate dielectric layer is in direct contact with the replacement channel layer.
8. A semiconductor device, comprising:
a bulk semiconductor substrate;
a fin on the bulk semiconductor substrate, the fin comprising a source region, a drain region and a channel region therebetween;
a replacement channel layer disposed in the channel region, wherein the replacement channel layer has a tapered sectional profile between the source region and the drain region;
a gate striding across the fin and surrounding the replacement channel layer;
an epitaxial source layer in the source region; and
an epitaxial drain layer in the drain region.
9. The semiconductor device according to claim 8 , wherein the fin comprises an upwardly convex surface that is in direct contact with a bottom surface of the replacement channel layer.
10. The semiconductor device according to claim 8 , wherein the replacement channel layer comprises a SiGe layer.
11. The semiconductor device according to claim 10 , wherein the SiGe layer is an un-doped SiGe layer.
12. The semiconductor device according to claim 8 , wherein the semiconductor device is a PMOS finFET device, and wherein the epitaxial source layer and the epitaxial drain layer are boron-doped SiGe epitaxial layers.
13. The semiconductor device according to claim 8 further comprising a gate dielectric layer between the gate and the replacement channel layer, and wherein the gate dielectric layer is in direct contact with the replacement channel layer.