Source/drain junction formation

1. A method of forming a source/drain region for a transistor, comprising:

forming a first recess in a substrate;

epitaxially growing a first semiconductor material in the first recess;

performing a first plasma implant comprising a pre-amorphization implant to the first semiconductor material;

following the first plasma implant, performing a second plasma doping comprising doping the first semiconductor material with phosphorus to form a first ultra-shallow junction in a first source/drain region, wherein the second plasma doping of the phosphorous is performed at a continuously decreasing energy level;

after the second plasma doping, forming a silicide layer over the first source/drain region; and

performing a microwave anneal on the first source/drain region at a first temperature between 300 and 600 degrees Celsius, wherein the microwave anneal substantially repairs damaged portions of a crystalline structure of the first source/drain region, wherein a concentration of the phosphorus at the first ultra-shallow junction is between about 2.0×10 21 atoms per centimeter cubed and about 4.0×10 21 atoms per centimeter cubed at a junction depth of about 8 to 10 nanometers.

2. The method of claim 1 , wherein the pre-amorphization implant is performed at least in part by implanting helium into the first semiconductor material.

3. The method of claim 1 , wherein the first semiconductor material comprises silicon phosphorous having a phosphorous concentration of less than about 1×10 20 atoms per centimeter cubed to about 7×10 20 atoms per centimeter cubed.

4. The method of claim 1 , wherein a collective process time of the first plasma implant and the second plasma doping is less than about thirty seconds.

5. The method of claim 1 , wherein the first plasma implant includes implanting helium at a continuously decreasing energy level.

6. The method of claim 1 , wherein a part of the first ultra-shallow junction is higher than a top surface of the substrate.

7. The method of claim 1 , wherein the microwave anneal uses free carrier absorption and dipole resonance heating.

8. The method of claim 1 , further comprising:

performing a third plasma doping/implant comprising doping a semiconductor material with boron simultaneously with implanting helium to form a second ultra-shallow junction in a second source/drain region, wherein the third plasma doping/implant is performed at a continuously decreasing energy;

after the third doping/implant, forming a second silicide over the second source/drain region; and

wherein a concentration of the boron in the second source/drain region beneath the second silicide is between about 3.0×10 15 atoms per centimeter cubed and about 1.0×10 16 atoms per centimeter cube at a depth of about 8 to 12 nanometers, and wherein an abruptness of boron at the second ultra-shallow junction is less than about 0.5 nanometers per decade.

9. The method of claim 1 , wherein the continuously decreasing energy level of the second plasma doping is in a range of about 6 kiloelectron-volts (keV) to about 4 kiloelectron-volts (keV), wherein a decreasing phosphorous concentration of 5.0×10 18 atoms per centimeter cube is between a depth of about 25 and 28 nm, wherein an abruptness of the decreasing concentration is about 5.5 to about 7.5 nanometers per decade, and wherein a resistance of the first source/drain region is reduced between about 30% to about 70%.

10. A method of forming a source/drain region for a transistor, comprising:

forming a recess in a substrate;

epitaxially growing a semiconductor material in the recess;

performing a doping of the semiconductor material with boron simultaneously with an implant of helium using a simultaneous plasma doping/implant to form an ultra-shallow function in the source/drain region;

after the doping the semiconductor material, forming a silicide over the source/drain region; and

performing a microwave anneal on the source/drain region at a first temperature between 300 and 600 degrees Celsius to substantially repair a damaged crystalline structure of the source/drain region, wherein a part of the ultra-shallow junction is higher than a top surface of the substrate, wherein a concentration of the boron in the source/drain region beneath the silicide is between about 3.0×10 15 atoms per centimeter cubed and about 1.0×10 16 atoms per centimeter cube at a depth of about 8 to 12 nanometers, and wherein an abruptness of boron at the ultra-shallow junction is less than about 0.5 nanometers per decade.

11. The method of claim 10 , wherein semiconductor material comprises silicon germanium boron (SiGeB).

12. The method of claim 10 , wherein the doping utilizes B 2 H 6 and a dose of the boron is about 4.5×10 16 atoms per centimeter squared.

13. The method of claim 10 , wherein the simultaneous plasma doping/implant comprises utilizing about 0.5% B 2 H 6 and about 99.5% helium.

14. The method of claim 10 , wherein a process time of the plasma doping/implant is less than fifteen seconds.

15. A method of forming a source/drain region for a transistor, comprising:

forming first recesses adjacent a first dummy gate in a substrate;

forming second recesses adjacent a second dummy gate in the substrate;

epitaxially growing a first semiconductor material in the first recesses;

epitaxially growing a second semiconductor material in the second recesses;

after the epitaxially growing the first semiconductor material, performing a pre-amorphization implant of the first semiconductor material using a first plasma helium implant;

after the performing the pre-amorphization implant, doping the first semiconductor material with an n-type dopant using a second plasma doping to form first source/drain regions, the first source/drain regions having ultra-shallow junctions, wherein the second plasma doping is performed at a continuously decreasing energy in a range of about 6 kiloelectron-volts (keV) to about 4 kiloelectron-volts (keV) during the second plasma doping, wherein a part of each of the ultra-shallow junctions is higher than a top surface of the substrate;

after the second plasma doping, forming a silicide over the first source/drain regions;

performing an anneal on the first source/drain region to substantially repair a damaged crystalline structure of the first source/drain regions;

after the epitaxially growing the second semiconductor material, doping the second semiconductor material with a p-type dopant and simultaneously implanting helium using a third plasma doping/implanting to form second source/drain regions, the second source/drain regions having ultra-shallow junctions;

after the simultaneous doping/implanting, forming a silicide over the second source/drain regions; and

performing an anneal on the second source/drain regions to substantially repair a damaged crystalline structure of the second source/drain regions.

16. The method of claim 15 , wherein the first plasma helium implant is performed at least in part by continuously decreasing an energy level during the first plasma implant and wherein a concentration of helium of the helium implant is about 1.0×10 16 to about 2.0×10 16 atoms per centimeter cubed.

17. The method of claim 15 , wherein the second semiconductor material comprises silicon germanium boron (SiGeB).

18. The method of claim 15 , wherein the anneal is a a microwave anneal using free carrier absorption and dipole resonance heating.

19. The method of claim 15 , wherein a concentration of boron in the first source/drain region beneath the silicide is between about 3.0×10 15 atoms per centimeter cubed and about 1.0×10 16 atoms per centimeter cube at a depth of about 8 to 12 nanometers, and wherein an abruptness of boron at the ultra-shallow junctions is less than about 0.5 nanometers per decade.

20. The method of claim 15 , wherein a peak doping concentration of phosphorous in the first source/drain region beneath the silicide is between about 2.0×10 21 atoms per centimeter cubed and about 4.0×10 21 atoms per centimeter cube at a depth of about 8 to 10 nanometers, wherein a decreasing phosphorous concentration of 5.0×10 18 atoms per centimeter cube is between a depth of about 25 and 28 nm, and wherein an abruptness of the decreasing phosphorous concentration is about 5.5 to about 7.5 nanometers per decade.