Gate material for semiconductor device fabrication
In forming an electronic device, a semiconductor layer is pre-doped and a dopant distribution anneal is performed prior to gate definition. Alternatively, the gate is formed from a metal. Subsequently formed shallow sources and drains, therefore, are not affected by the gate annealing step.
1. A method for forming a structure, the method comprising the steps of:
providing a substrate comprising a semiconductor material;
defining an n-type metal-oxide semiconductor field-effect transistor (NMOSFET) disposed over the substrate, the NMOSFET including:
a first source and a first drain defining a first channel therebetween and each of the first source and first drain comprising n-type dopants,
a first gate disposed above the first channel, the first gate having a first workfunction and comprising a first metal, and
a first gate dielectric layer disposed between the first gate and the first channel; and
defining a p-type metal-oxide semiconductor field-effect transistor (PMOSFET) over the substrate, the PMOSFET including:
a second source and a second drain, defining a second channel therebetween and each of the second source and second drain comprising p-type dopants;
a second gate disposed above the second channel, the second gate having a second workfunction and comprising a second metal; and
a second gate dielectric layer disposed between the second gate and the second channel,
wherein the first workfunction is substantially different from the second workfunction, and at least one of the first channel and the second channel comprises a strained semiconductor channel material.
2. The method of claim 1 , wherein each of the first channel and the second channel comprises the strained semiconductor channel material.
3. The method of claim 1 , wherein the first channel is under tensile strain and the second channel is under compressive strain.
4. The method of claim 3 , wherein the strained semiconductor channel material is silicon.
5. The method of claim 4 , wherein the substrate induces substantially none of the strain of the strained semiconductor channel material.
6. The method of claim 1 , wherein at least one of the first channel and the second channel consists essentially of the strained semiconductor channel material.
7. The method of claim 6 , wherein the strained semiconductor channel material is silicon.
8. The method of claim 7 , wherein the silicon comprises isotopically pure silicon.
9. The method of claim 7 , wherein the strained semiconductor channel material is disposed on and in contact with the substrate and the substrate consists essentially of silicon.
10. The method of claim 7 , wherein the strained semiconductor channel material is disposed in contact with relaxed silicon.
11. The method of claim 1 , wherein the semiconductor channel material is the same as the substrate semiconductor material.
12. The method of claim 1 , wherein the substrate induces substantially none of the strain of the strained semiconductor channel material.
13. The method of claim 1 , wherein the substrate consists essentially of silicon.
14. The method of claim 1 , wherein at least one of the first and second gates consists essentially of a doped metal-semiconductor alloy.
15. The method of claim 14 , wherein both the first and second gates consist essentially of a doped metal-semiconductor alloy.
16. The method of claim 15 , wherein the metal of the metal-semiconductor alloy comprises nickel.
17. The method of claim 16 , wherein the metal consists essentially of nickel.
18. The method of claim 1 , wherein at least one of the first source, first drain, second source, and second drain comprises a second semiconductor material.
19. The method of claim 18 , wherein the second semiconductor material comprises strained SiGe.
20. The method of claim 18 , wherein the second semiconductor material comprises relaxed SiGe.
21. The method of claim 1 , wherein at least one of the first gate dielectric layer and the second gate dielectric layer comprises a high-k dielectric material.
22. The method of claim 21 , wherein both the first gate dielectric and the second gate dielectric comprise a high-k dielectric material.
23. The method of claim 1 , further comprising performing an activation anneal to activate at least one of the n-type dopants and p-type dopants.
24. The method of claim 23 , wherein the activation anneal comprises at least one of a flash lamp anneal and a laser anneal.
25. The method of claim 1 , further comprising providing a strained layer over the substrate.
26. The method of claim 25 , wherein the strained layer comprises germanium.
27. The method of claim 26 , wherein the strained layer consists essentially of SiGe.
28. The method of claim 27 , wherein the strained layer is formed by chemical vapor deposition.
29. The method of claim 28 , wherein the chemical vapor deposition is performed in a single-wafer reactor with a germane precursor.
30. The method of claim 1 , wherein at least one of the first source, first drain, second source, and second drain regions comprises an extension including SiGe.