Fin field effect transistor including asymmetric raised active regions
Merged and unmerged raised active regions on semiconductor fins can be simultaneously formed on a same substrate by control of growth rates of a deposited semiconductor material on surfaces of the semiconductor fins. In one embodiment, a growth-rate-retarding dopant can be implanted by angled ion implantation onto sidewall surfaces of first semiconductor fins on which retardation of growth rates is desired, while second semiconductor fins are masked by a masking layer. In another embodiment, a growth-rate-enhancing dopant can be implanted by ion implantation onto sidewall surfaces of second semiconductor fins, while first semiconductor fins are masked by a masking layer. The differential growth rates of the deposited semiconductor material can cause raised active regions on the first semiconductor fins to remain unmerged, and raised active regions on the second semiconductor fins to become merged.
1. A semiconductor structure comprising:
a semiconductor fin located on a substrate and having a first sidewall contained within a first vertical plane and a second sidewall contained within a second vertical plane that is parallel to said first vertical plane, wherein a dopant-including surface region including a species of dopants is located within said semiconductor fin, and contacting one of said first sidewall and said second sidewall; and
a raised active region comprising a semiconductor material and having an asymmetric vertical cross-sectional shape along a vertical plane perpendicular to said first and second vertical planes.
2. The semiconductor structure of claim 1 , wherein said asymmetric vertical cross-sectional shape includes a first region located on an opposite side of said semiconductor fin with respect to said first vertical plane, and a second region located on an opposite side of said semiconductor fin with respect to said second vertical plane, wherein said first region has a greater maximum lateral extent than said second region.
3. The semiconductor structure of claim 1 , wherein said first region has a shape that includes a corner at which a pair of non-horizontal and non-vertical faceted surfaces of said raised active region is joined.
4. The semiconductor structure of claim 3 , wherein said second region has a shape that includes a side that is parallel to said second vertical plane.
5. A semiconductor structure comprising:
a semiconductor fin located on a substrate and having a first sidewall contained within a first vertical plane and a second sidewall contained within a second vertical plane that is parallel to said first vertical plane; and
a raised active region comprising a semiconductor material and having an asymmetric vertical cross-sectional shape along a vertical plane perpendicular to said first and second vertical planes, wherein said asymmetric vertical cross-sectional shape includes a first region located on an opposite side of said semiconductor fin with respect to said first vertical plane, and a second region located on an opposite side of said semiconductor fin with respect to said second vertical plane, wherein said first region has a greater maximum lateral extent than said second region, and wherein said first region has a shape that includes a corner at which a pair of non-horizontal and non-vertical faceted surfaces of said raised active region is joined.
6. The semiconductor structure of claim 1 , wherein said dopant-including surface region has an upper portion having a same width as said semiconductor fin and a lower portion having a width that is less than said same width.
7. The semiconductor structure of claim 1 , wherein said semiconductor fin includes a cuboid active region in contact with said dopant-including surface region and not including said species of dopants.
8. The semiconductor structure of claim 1 , further comprising a gate stack straddling said semiconductor fin, said gate stack comprising a gate dielectric and a gate electrode.
9. The semiconductor structure of claim 1 , further comprising:
another semiconductor fin located on said substrate and having sidewalls that are parallel to said first and second vertical planes; and
another raised active region comprising said semiconductor material and having another asymmetric vertical cross-sectional shape along said vertical plane perpendicular to said first and second vertical planes that is congruent to said asymmetric vertical cross-sectional shape,
wherein said raised active region and said another raised active region are laterally spaced from each other by a distance less than a lateral extent of said asymmetric vertical cross-sectional shape.
10. The semiconductor structure of claim 9 , further comprising:
a plurality of parallel semiconductor fins having a pitch that is the same as a sum of a width of said semiconductor fin and a lateral distance between said semiconductor fin and said another semiconductor fin; and
a merged raised active region comprising said semiconductor material and in contact with said plurality of parallel semiconductor fins.
11. The semiconductor structure of claim 5 , further comprising a dopant-including surface region including a species of dopants located within said semiconductor fin, and contacting one of said first sidewall and said second sidewall.
12. A semiconductor structure comprising:
a semiconductor fin located on a substrate and having a first sidewall contained within a first vertical plane and a second sidewall contained within a second vertical plane that is parallel to said first vertical plane;
a raised active region comprising a semiconductor material and having an asymmetric vertical cross-sectional shape along a vertical plane perpendicular to said first and second vertical planes;
another semiconductor fin located on said substrate and having sidewalls that are parallel to said first and second vertical planes; and
another raised active region comprising said semiconductor material and having another asymmetric vertical cross-sectional shape along said vertical plane perpendicular to said first and second vertical planes that is congruent to said asymmetric vertical cross-sectional shape, wherein said raised active region and said another raised active region are laterally spaced from each other by a distance less than a lateral extent of said asymmetric vertical cross-sectional shape.