Method, apparatus, and system having super steep retrograde well with engineered dopant profiles
Generally, in one embodiment, the present disclosure is directed to a method for forming a transistor. The method includes: implanting a substrate to form at least one of an n and p doped region; depositing an epitaxial semiconductor layer over the substrate; forming trenches through the epitaxial layer and partially through at least one of an n and p doped region; forming dielectric isolation regions in the trenches; forming a fin in an upper portion of the epitaxial semiconductor layer by partially recessing the dielectric isolation regions; forming a gate dielectric adjacent at least two surfaces of the fin; and diffusing dopant from at least one of the n and p doped regions at least partially into the epitaxial semiconductor layer to form a diffusion doped transition region adjacent a bottom portion of the fin.
1. A finFET transistor, comprising:
a substrate having at least one of an n doped region and a p doped region;
a fin having a lowly doped channel region;
a subfin region including a dopant diffusion inhibiting material intermediate the substrate and the channel of the fin, wherein the dopant diffusion inhibiting material is silicon carbon having a concentration of carbon less than 2.0%; and
a moderately doped region beneath the dopant diffusion inhibiting material.
2. The finFET transistor of 1 , wherein the silicon carbon has a concentration of carbon in a range of about 0.05 to about 1.0%.
3. The finFET transistor of claim 1 , wherein the silicon carbon has a thickness in a range of about 2 nm to about 30 nm.
4. The finFET transistor of claim 1 , wherein the silicon carbon has a concentration of carbon in a range of about 0.1 to about 0.4% and has a thickness in a range of about 5 nm to about 20 nm.
5. The finFET transistor of claim 1 , wherein the lowly doped channel region has an average active dopant concentration of less than about 8×10 17 cm −3 .
6. The finFET transistor of claim 1 wherein the moderately doped region has an average active dopant concentration in a range of about 8×10 17 cm −3 and about 6×10 18 cm −3 in a region comprising at least about 40 nm adjacent the dopant diffusion inhibiting material.
7. The finFET transistor of claim 1 wherein the dopant diffusion inhibiting material has a thickness in a range of about 5 nm to about 20 nm.
8. The finFET transistor of claim 1 , further comprising a shallow trench isolation (STI) dielectric adjacent a first side and a second side of the subfin region.
9. The finFET transistor of claim 1 , further comprising:
a gate dielectric disposed over the fin; and
a gate electrode disposed over the gate dielectric.
10. A finFET transistor, comprising:
a substrate comprising an n doped region and a p doped region;
a first fin disposed above the n doped region and having a doped channel region having a first doping concentration;
a second fin disposed above the p doped region and having a doped channel region having the first doping concentration;
a first subfin region including a dopant diffusion inhibiting material intermediate the substrate and the channel of the first fin;
a second subfin region including a dopant diffusion inhibiting material intermediate the substrate and the channel of the second fin;
a first doped region beneath the first subfin region and having a second doping concentration; and
a second doped region beneath the second subfin region and having the second doping concentration; wherein the second doping concentration is greater than the first doping concentration.
11. The finFET transistor of claim 10 , wherein the dopant diffusion inhibiting material of the first subfin region and the dopant diffusion inhibiting material of the second subfin region comprise silicon carbon and wherein the dopant diffusion inhibiting material of the first subfin region and the dopant diffusion inhibiting material of the second subfin region each have a concentration of carbon in a range of about 0.05 to about 1.0%.
12. The finFET transistor of claim 10 , wherein the dopant diffusion inhibiting material of the first subfin region and the dopant diffusion inhibiting material of the second subfin region each have a thickness in a range of about 2 nm to about 30 nm.
13. The finFET transistor of claim 12 , wherein the dopant diffusion inhibiting material of the first subfin region and the dopant diffusion inhibiting material of the second subfin region each have a thickness in a range of about 5 nm to about 20 nm.
14. The finFET transistor of claim 10 , wherein the dopant diffusion inhibiting material of the first subfin region and the dopant diffusion inhibiting material of the second subfin region each have a concentration of carbon in a range of about 0.1 to about 0.4% and a thickness in a range of about 5 nm to about 20 nm.
15. The finFET transistor of claim 10 , wherein the doped channel region of the first fin and the doped channel region of the second fin each have an average active dopant concentration of less than about 8×10 17 cm −3 .
16. The finFET transistor of claim 10 , further comprising a shallow trench isolation (STI) dielectric between the first subfin region and the second subfin region.
17. The finFET transistor of claim 10 , further comprising:
a first gate dielectric disposed over the first fin;
a second gate dielectric disposed over the second fin; and
a gate electrode disposed over the first gate dielectric and the second gate dielectric.
18. A finFET device, comprising:
a substrate comprising an n doped region and a p doped region;
a first fin disposed above the n doped region and having a first doped channel region;
a second fin disposed above the p doped region and having a second doped channel region;
a first subfin region including a dopant diffusion inhibiting material intermediate the substrate and the channel of the first fin;
a second subfin region including a dopant diffusion inhibiting material intermediate the substrate and the channel of the second fin;
a third doped region beneath the first subfin region; and
a fourth doped region beneath the second subfin region;
wherein the first and second doped regions each has a first dopant concentration and the third and fourth doped regions each has a second dopant concentration, wherein the second dopant concentration is greater than the first dopant concentration.
19. The finFET device of claim 18 , further comprising:
a shallow trench isolation (STI) dielectric between the first subfin region and the second subfin region;
a first gate dielectric disposed over the first fin;
a second gate dielectric disposed over the second fin; and
a gate electrode disposed over the first gate dielectric and the second gate dielectric.