Nanowire structures having non-discrete source and drain regions

1. A method of fabricating a nanowire semiconductor device, the method comprising:

forming a plurality of vertically stacked nanowires above a substrate, each of the nanowires comprising a discrete channel region disposed in the nanowire;

forming a gate electrode stack surrounding the discrete channel regions of the plurality of vertically stacked nanowires;

forming a pair of non-discrete source and drain regions on either side of, and adjoining, the discrete channel regions of the plurality of vertically stacked nanowires, each of the non-discrete source and drain regions having an uppermost surface, sidewall surfaces and a bottommost surface; and

subsequent to forming the pair of non-discrete source and drain regions, forming a first conductive contact on and continuous around the uppermost surface, the sidewall surfaces and the bottommost surface of the non-discrete source region, and forming a second conductive contact on and continuous around the uppermost surface, the sidewall surfaces and the bottommost surface of the non-discrete drain region.

2. The method of claim 1 , wherein forming the pair of non-discrete source and drain regions comprises first forming discrete source and drain regions for each of the nanowires.

3. The method of claim 2 , wherein forming the pair of non-discrete source and drain regions comprises forming a faceted semiconductor material at least partially surrounding the discrete source and drain regions of each of the nanowires.

4. The method of claim 1 , wherein forming the pair of non-discrete source and drain regions comprises melting, by laser anneal, a portion of vertically stacked nanowires of a first semiconductor material along with an intervening second semiconductor material and a surrounding semiconductor layer.

5. The method of claim 1 , wherein the non-discrete source and drain regions are formed prior to forming the discrete channel regions.

6. The method of claim 1 , wherein the non-discrete source and drain regions are formed subsequent to forming the discrete channel regions.

7. A method of fabricating a nanowire semiconductor device, the method comprising:

forming a plurality of vertically stacked nanowires above a substrate, each of the nanowires comprising a discrete channel region disposed in the nanowire;

forming a gate electrode stack surrounding the discrete channel regions of the plurality of vertically stacked nanowires;

removing source and drain regions of each of the plurality of vertically stacked nanowires;

forming a pair of non-discrete source and drain regions on either side of, and adjoining, the discrete channel regions of the plurality of vertically stacked nanowires, each of the non-discrete source and drain regions having an uppermost surface, sidewall surfaces and a bottommost surface; and

subsequent to forming the pair of non-discrete source and drain regions, forming a first conductive contact on and continuous around the uppermost surface, the sidewall surfaces and the bottommost surface of the non-discrete source region, and forming a second conductive contact on and continuous around the uppermost surface, the sidewall surfaces and the bottommost surface of the non-discrete drain region.

8. The method of claim 7 , wherein the pair of non-discrete source and drain regions provides contact to the plurality of vertically stacked nanowires.

9. The method of claim 8 , wherein the pair of non-discrete source and drain regions consists essentially of metal.