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 method for forming a transistor, comprising:
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, wherein the diffusion doped transition region adjacent a bottom portion of the fin has a higher dopant concentration than the diffusion doped transition region adjacent the at least one of the n and p doped region.
2. The method of claim 1 , further comprising depositing a dopant diffusion inhibiting material intermediate the substrate and the epitaxial semiconductor layer.
3. The method of claim 2 , wherein depositing the dopant diffusion inhibiting material intermediate the substrate and the epitaxial semiconductor layer further comprises depositing an epitaxial layer of silicon carbon intermediate the substrate and the epitaxial semiconductor layer.
4. The method of claim 3 , wherein depositing the epitaxial layer of silicon carbon intermediate the substrate and the epitaxial semiconductor layer further comprises depositing an epitaxial layer of silicon carbon intermediate the substrate and the epitaxial semiconductor layer having a concentration of carbon in a range of about 0.05 to about 1.0%.
5. The method of claim 3 , wherein depositing the layer of silicon carbon intermediate the substrate and the epitaxial semiconductor layer further comprises depositing a layer of silicon carbon intermediate the substrate and the epitaxial semiconductor layer having a thickness in a range of about 2 nm to about 30 nm.
6. The method of claim 3 , wherein depositing the epitaxial layer of silicon carbon intermediate the substrate and the epitaxial semiconductor layer further comprises depositing a an epitaxial layer of silicon carbon intermediate the substrate and the epitaxial semiconductor layer having a concentration of carbon in a range of about 0.1 to about 0.4% and having a thickness in a range of about 5 nm to about 20 nm.
7. The method of claim 1 , wherein implanting the substrate to form the at least one of the n and p doped region further comprises implanting the substrate with at least one of boron (B), gallium (Ga), and indium (In) using a peak dopant concentration in a range of about 8×10 17 cm −3 and about 2×10 19 cm −3 .
8. The method of claim 1 , wherein implanting the substrate to form the at least one of the n and p doped region further comprises implanting the substrate with at least one of boron (B), gallium (Ga), and indium (In) to produce an average dopant concentration over about the first 40 nm of depth in a range of about 8×10 17 cm −3 and about 6×10 18 cm −3 .
9. The method of claim 1 , wherein implanting the substrate to form the at least one of the n and p doped region further comprises implanting the substrate with at least one of phosphorus (P), arsenic (As) and antimony (Sb) using a peak dopant concentration in a range of about 8×10 17 cm −3 and about 2×10 19 cm −3 .
10. The method of claim 1 , wherein implanting the substrate to form the at least one of the n and p doped region further comprises implanting the substrate with at least one of phosphorus (P), arsenic (As) and antimony (Sb) to produce an average dopant concentration over about the first 40 nm of depth in a range of about 8×10 17 cm −3 and about 6×10 18 cm −3 .
11. The method of claim 1 , wherein 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 the bottom portion of the fin further comprises forming a diffusion doped transition region having a dopant concentration adjacent the bottom of the fin that is at least a factor of 2 lower than a dopant concentration of the diffusion doped transition region adjacent the substrate implanted to form at least one of the n and p doped region.
12. The method of claim 1 , wherein 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 the bottom portion of the fin further comprises forming a diffusion doped transition region having a thickness in a range of about 5 nm to about 30 nm.
13. The method of claim 1 , wherein implanting the substrate to form the at least one of the n and p doped region further comprises implanting the substrate to form at least one n doped region and at least one p doped region and forming at least one pMOS transistor and at least one nMOS transistor therefrom.