Stressed channel bulk fin field effect transistor
Effective transfer of stress to a channel of a fin field effect transistor is provided by forming stress-generating active semiconductor regions that function as a source region and a drain region on a top surface of a single crystalline semiconductor layer. A dielectric material layer is formed on a top surface of the semiconductor layer between semiconductor fins. A gate structure is formed across the semiconductor fins, and the dielectric material layer is patterned employing the gate structure as an etch mask. A gate spacer is formed around the gate stack, and physically exposed portions of the semiconductor fins are removed by an etch. Stress-generating active semiconductor regions are formed by selective epitaxy from physically exposed top surfaces of the semiconductor layer, and apply stress to remaining portions of the semiconductor fins that include channels.
1. A semiconductor structure comprising:
a single crystalline material layer located in a substrate;
a plurality of semiconductor fins located directly on a first portion of a top surface of said single crystalline material layer;
at least one dielectric material portion located directly on a second portion of said top surface of said single crystalline material layer and laterally between each semiconductor fin of said plurality of semiconductor fins;
a gate structure including a vertical stack of a gate dielectric and a gate electrode and contacting a top surface of each of said at least one dielectric material portion and sidewalls of said plurality of semiconductor fins; and
a gate spacer laterally contacting sidewalls of said gate structure and sidewalls of said at least one dielectric material portion and a third portion of said top surface of said single crystalline material layer.
2. The semiconductor structure of claim 1 , wherein all sidewall surfaces of said at least one dielectric material portion are vertically coincident with sidewalls of said gate structure or sidewalls of said plurality of semiconductor fins.
3. The semiconductor structure of claim 1 , further comprising:
a source region overlying a fourth portion of said top surface of single crystalline material layer and in contact with first sidewalls of said plurality of semiconductor fins; and
a drain region overlying a fifth portion of said topmost surface of said single crystalline material layer and in contact with second sidewalls of said plurality of semiconductor fins.
4. The semiconductor structure of claim 3 , wherein bottom surfaces of said source region and said drain region are located below a horizontal plane including at least one top surface of said at least one dielectric material portion.
5. The semiconductor structure of claim 3 , wherein said at least one dielectric material portion is laterally spaced from said source region and said drain region by a width of said gate spacer.
6. The semiconductor structure of claim 3 , wherein each of said source region and said drain region is single crystalline and is epitaxially aligned to a single crystalline material within said single crystalline material layer.
7. The semiconductor structure of claim 6 , wherein said source region and said drain region comprise a doped semiconductor material having a lattice constant that is different from a lattice constant of said single crystalline material, and apply a stress to said plurality of semiconductor fins.
8. The semiconductor structure of claim 3 , wherein each of said source region and said drain region is in physical contact with said top surface of said single crystalline material layer.
9. The semiconductor structure of claim 3 , further comprising:
a source-side intrinsic semiconductor material portion in contact with said fourth portion of said top surface of said single crystalline material layer and a bottom surface of said source region; and
a drain-side intrinsic semiconductor material portion in contact with said fifth portion of said top surface of said single crystalline material layer and a bottom surface of said drain region.
10. The semiconductor structure of claim 1 , wherein interfaces between said plurality of semiconductor fins and said source region and interfaces between said plurality of semiconductor fins and said drain region are vertically coincident with outer sidewalls of said gate spacer.
11. The semiconductor structure of claim 1 , wherein said at least one dielectric material portion has a bottommost surface that is coplanar with a bottommost surface of each semiconductor fin of said plurality of semiconductor fins.
12. The semiconductor structure of claim 1 , wherein said single crystalline material layer is a rare-earth oxide material.
13. The semiconductor structure of claim 12 , wherein said rare-earth oxide comprises a rare earth element selected from La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu.