Moon-shaped bottom spacer for vertical transport field effect transistor (VTFET) devices
A uniform moon-shaped bottom spacer for a VTFET device is provided utilizing a replacement bottom spacer that is epitaxially grown above a bottom source/drain region. After filling a trench that is formed into a substrate with a dielectric fill material that also covers the replacement bottom spacer, the replacement bottom spacer is accessed, removed and then replaced with a moon-shaped bottom spacer.
1. A vertical transport field effect transistor (VTFET) device comprising:
at least one semiconductor fin extending upward from a surface of a substrate and located in a first active device region, wherein a trench isolation structure is located in the substrate and at an edge of the first active device region;
a bottom source/drain region located beneath, and on each side of, the at least one semiconductor fin;
a moon-shaped bottom spacer located laterally adjacent to a lower portion of at least a first side of the at least one semiconductor fin and above the bottom source/drain region, wherein the moon-shaped bottom spacer has a convex upper surface and a planar bottommost surface;
a functional gate structure contacting a middle portion of the at least one semiconductor fin and located on the convex upper surface of the moon-shaped bottom spacer;
a top spacer contacting an upper portion of the at least one semiconductor fin and on a surface of the functional gate structure; and
a top source/drain region contacting an upper surface of the at least one semiconductor fin.
2. The VTFET device of claim 1 , further comprising a cut moon-shaped spacer located laterally adjacent to the lower portion of a second side of the at least one semiconductor fin and located in the first active device region and at an edge of the trench isolation structure.
3. The VTFET device of claim 1 , further comprising a bottom source/drain contact structure contacting the bottom source/drain region, a top source/drain contact structure contacting the top source/drain region and a gate contact structure contacting the functional gate structure.
4. The VTFET device of claim 3 , wherein each of the bottom source/drain contact structure, the top source/drain contact structure, and the gate contact structure is embedded in an interlayer dielectric (ILD) material layer.
5. The VTFET device of claim 4 , wherein the bottom source/drain contact structure has a topmost surface that is coplanar with a topmost surface of each of the top source/drain contact structure, the gate contact structure and the ILD material layer.
6. The VTFET device of claim 1 , wherein the moon-shaped bottom spacer is composed of a dielectric material having a dielectric constant of less than 7.0.
7. The VTFET device of claim 6 , wherein the moon-shaped bottom spacer is composed of a dielectric material containing atoms of Si, C and 0 , a dielectric material containing atoms of Si, B, C and N, or a dielectric material containing atoms of Si and C.
8. The VTFET device of claim 1 , wherein the substrate is a semiconductor material.
9. The VTFET device of claim 1 , wherein the functional gate structure includes at least a gate dielectric material and a gate electrode, wherein the gate dielectric material physically contacts the middle portion of the at least one semiconductor fin.
10. The VTFET device of claim 1 , wherein the moon-shaped bottom spacer is located directly on a surface of the bottom source/drain region.
11. The VTFET device of claim 1 , wherein the moon-shaped bottom spacer is spaced apart from the bottom source/drain region by a semiconductor layer.
12. The VTFET device of claim 1 , further comprising a second active device region located laterally adjacent to the first active device region, wherein the first and second active device regions are isolated by the trench isolation structure.
13. The VTFET device of claim 12 , wherein the second active device region comprises at least one other semiconductor fin extending upward from the substrate, another bottom source/drain region located beneath, and on each side of, the at least one other semiconductor fin, another moon-shaped bottom spacer located laterally adjacent to a lower portion of at least a first side of the at least one other semiconductor fin and on a surface of the another bottom source/drain region, another functional gate structure contacting a middle portion of the at least one other semiconductor fin and located above the another moon-shaped bottom spacer, and another top spacer contacting an upper portion of the at least one other semiconductor fin and on a surface of the another functional gate structure, and another top source/drain region contacting an upper surface of the at least one other semiconductor fin.
14. A vertical transport field effect transistor (VTFET) device comprising:
at least one semiconductor fin extending upward from a surface of a substrate and located in a first active device region, wherein a trench isolation structure is located in the substrate and at an edge of the first active device region;
a bottom source/drain region located beneath, and on each side of, the at least one semiconductor fin;
a moon-shaped bottom spacer located laterally adjacent to a lower portion of at least a first side of the at least one semiconductor fin and above the bottom source/drain region, wherein the moon-shaped bottom spacer has a convex first surface and a planar second surface, opposite the convex first surface;
a functional gate structure contacting a middle portion of the at least one semiconductor fin and located directly on the convex first surface of the moon-shaped bottom spacer;
a top spacer contacting an upper portion of the at least one semiconductor fin and on a surface of the functional gate structure; and
a top source/drain region contacting an upper surface of the at least one semiconductor fin.