Methods of forming bulk FinFET devices so as to reduce punch through leakage currents

1. A method of forming a FinFET device comprised of a gate structure, the method comprising:

forming a plurality of trenches in a semiconducting substrate to thereby define a plurality of spaced-apart fins in a semiconducting substrate, each of said trenches having a bottom surface;

forming a doped liner layer of insulating material on said fins and on the entire bottom surface of said trenches;

forming an undoped layer of insulating material above said doped liner layer such that said undoped layer of insulating material overfills said trenches and is positioned between said fins, wherein said undoped layer of insulating material has an upper surface that is positioned at a level that is above a level of an upper surface of said fins and above an upper surface of said doped liner layer;

performing at least one recess etching process to consume a portion of said doped liner layer and a portion of said undoped layer of insulating material to thereby define a recessed doped liner layer of insulating material and a recessed undoped layer of insulating material said recessed doped liner layer covering the entire bottom surface of said trenches and having a recessed upper surface that is positioned at a level that is below a level of the upper surface of each of said fins, wherein an exposed portion of each of said fins extends above said recessed upper surface of said recessed doped liner layer of insulating material while a covered portion of each of said fins is positioned below said recessed upper surface of said recessed doped liner layer of insulating material;

forming said gate structure comprised of a gate insulation layer and a gate electrode around said exposed portions of each of said fins and above said recessed doped liner layer of insulating material positioned on the entire bottom surface of said trenches and said recessed undoped layer of insulating material; and

at some point after forming said recessed doped liner layer of insulating material, performing at least one process operation to heat at least said recessed doped liner layer of insulating material to cause a dopant material in said recessed doped liner layer of insulating material to migrate from said recessed doped liner layer of insulating material into said covered portions of said fins and thereby define a doped region in said covered portions of said fins that is positioned under said exposed portions of said fins.

2. The method of claim 1 , wherein forming said doped liner layer of insulating material comprises introducing said dopant material into said doped liner layer of insulating material by performing an in situ doping process whereby said dopant material is introduced into said doped liner layer of insulating material as it is being formed.

3. The method of claim 1 , wherein forming said doped liner layer of insulating material comprises:

depositing an undoped liner layer of insulating material; and

performing at least one ion implantation process to introduce said dopant material into said undoped liner layer of insulating material.

4. The method of claim 1 , wherein said FinFET device is an N-type FinFET device and wherein said doped liner layer of insulating material is doped with a P-type dopant.

5. The method of claim 4 , wherein said doped liner layer of insulating material is boron silicate glass (BSG).

6. The method of claim 1 , wherein said FinFET device is a P-type FinFET device and wherein said doped liner layer of insulating material is doped with an N-type dopant.

7. The method of claim 6 , wherein said doped liner layer of insulating material is phosphorus silicate glass (PSG).

8. The method of claim 1 , wherein said doped liner layer of insulating material has a dopant concentration of about 10 22 -10 23 ion/cm −1 .

9. The method of claim 1 , wherein said doped region in said covered portions of said fins has a dopant concentration of about 10 19 -10 21 ion/cm 3 .

10. The method of claim 1 , wherein said doped region in said covered portions of said fins extends along an entire axial length of each of said fins.

11. The method of claim 1 , wherein said doped region in said covered portions of said fins is positioned below said gate structure for said device.

12. A method of forming a FinFET device comprised of a gate structure, the method comprising:

forming a plurality of trenches in a semiconducting substrate to thereby define a plurality of spaced-apart fins in a semiconducting substrate, each of said trenches having a bottom surface;

performing an in situ doping deposition process to form a doped liner layer of insulating material on said fins and on the entire bottom surface of said trenches, said doped liner layer of insulating material comprising a dopant material;

depositing an undoped layer of insulating material in said trenches above said doped liner layer of insulating material such that it overfills said trenches and is positioned between said fins, wherein said undoped layer of insulating material has an upper surface that is positioned at a level that is above a level of an upper surface of said fins and above an upper surface of said doped liner layer,

performing at least one recess etching process to consume a portion of said doped liner layer and a portion of said undoped layer of insulating material to thereby define a recessed doped liner layer of insulating material and a recessed undoped layer of insulating material, said recessed doped liner layer of insulating material covering the entire bottom surface of said trenches and having a recessed upper surface that is positioned at a level that is below a level of an upper surface of each of said fins, wherein an exposed portion of each of said fins extends above said recessed upper surface of said doped liner layer of insulating material while a covered portion of each of said fins is positioned below said recessed upper surface of said doped liner layer of insulating material;

forming said gate structure comprised of a gate insulation layer and a gate electrode around said exposed portions of each of said fins and above said recessed doped liner layer of insulating material positioned on the entire bottom surface of said trenches and said recessed undoped layer of insulating material; and

at some point after forming said recessed doped liner layer of insulating material, performing at least one process operation to heat at least said recessed doped liner layer of insulating material to cause a dopant material in said recessed doped liner layer of insulating material to migrate from said recessed doped liner layer of insulating material into said covered portions of said fins and thereby define a doped region in said covered portions of said fins that is positioned under said exposed portions of said fins.

13. The method of claim 12 , wherein said FinFET device is an N-type FinFET device and wherein said doped liner layer of insulating material is doped with a P-type dopant.

14. The method of claim 13 , wherein said doped liner layer of insulating material is boron silicate glass (BSG).

15. The method of claim 12 , wherein said FinFET device is a P-type FinFET device and wherein said doped liner layer of insulating material is doped with an N-type dopant.

16. The method of claim 15 , wherein said doped liner layer of insulating material is phosphorus silicate glass (PSG).

17. The method of claim 12 , wherein said doped liner layer of insulating material has a dopant concentration of about 10 22 -10 23 ion/cm 3 .

18. The method of claim 12 , wherein said doped region in said covered portions of said fins has a dopant concentration of about 10 19 -10 21 ion/cm 3 .

19. The method of claim 12 , wherein said doped region in said covered portions of said fins extends along an entire axial length of each of said fins.