Method for forming a nitrided germanium-containing layer using plasma processing

1. A method for forming a dielectric layer of a semiconductor device, the method comprising:

providing a germanium-containing substrate in a process chamber;

generating a plasma from a process gas containing N 2 and a noble gas, and selecting the plasma conditions effective to form plasma excited N 2 species while suppressing formation of plasma excited N species;

exposing the germanium-containing substrate to the plasma to form a nitrided germanium-containing layer on the germanium-containing substrate, wherein the nitrided germanium-containing layer comprises a germanium-containing oxynitride layer containing a greater amount of nitrogen species insoluble in H 2 O than nitrogen species soluble in H 2 O and a greater amount of oxygen species soluble in H 2 O than oxygen species insoluble in H 2 O; and

exposing the germanium-containing oxynitride layer to liquid H 2 O or gaseous H 2 O to reduce the thickness and increase the nitrogen concentration of the germanium-containing oxynitride layer by removing at least a portion of the oxygen species soluble in H 2 O.

2. The method according to claim 1 , wherein the plasma excited N 2 species comprise N 2 + ions and N 2 radicals, and the plasma excited N species comprise N radicals.

3. The method according to claim 1 , wherein the process gas comprises N 2 , a noble gas, and H 2 .

4. The method according to claim 1 , further comprising:

maintaining the substrate at a temperature between room temperature and about 500° C. during the exposing.

5. The method according to claim 1 , wherein the germanium-containing oxynitride layer is a germanium oxynitride layer or a silicon germanium oxynitride layer.

6. The method according to claim 1 , wherein the germanium-containing substrate is germanium, or germanium and silicon.

7. The method according to claim 6 , wherein the germanium-containing substrate further comprises a base dielectric layer containing oxygen overlying the germanium-containing substrate and the exposing comprises exposing the base dielectric layer to the plasma to form a nitrided base dielectric layer that comprises the germanium-containing oxynitride.

8. The method according to claim 1 , wherein the process gas further comprises an oxygen-containing gas.

9. The method according to claim 1 , wherein the process gas further comprises an oxygen-containing background gas.

10. The method according to claim 1 , wherein the germanium-containing substrate comprises an oxide layer or an adsorbed oxygen-containing species.

11. The method according to claim 1 , wherein the generating further comprises:

monitoring light emission from the excited species in the plasma by optical emission spectroscopy, wherein the excited species comprise N 2 + ions, N 2 radicals, and N radicals; and

adjusting the plasma conditions based on the monitoring.

12. The method according to claim 1 , wherein the plasma is generated by a microwave plasma source comprising an antenna.

13. The method according to claim 1 , wherein the plasma is generated by a radial line slot antenna plasma source.

14. The method according to claim 1 , wherein the nitrogen species insoluble in H 2 O include Ge 3 N 4 , the oxygen species soluble in H 2 O include GeO 2 , the nitrogen species soluble in H 2 O include GeN, and the oxygen species insoluble in H 2 O include GeO.

15. A method for forming a dielectric layer of a semiconductor device, the method comprising:

providing a germanium-containing substrate in a process chamber;

generating a plasma from a process gas containing N 2 and a noble gas, and selecting the plasma conditions effective to form plasma excited N 2 species while suppressing formation of plasma excited N species, wherein the plasma excited N 2 species comprise N 2 + ions and N 2 radicals, and the plasma excited N species comprise N radicals;

exposing the germanium-containing substrate to the plasma to form a germanium oxynitride layer on the germanium-containing substrate, wherein the germanium oxynitride layer contains a greater amount of nitrogen species insoluble in H 2 O than nitrogen species soluble in H 2 O and a greater amount of oxygen species soluble in H 2 O than oxygen species insoluble in H 2 O; and

exposing the germanium oxynitride layer to liquid H 2 O or gaseous H 2 O to reduce the thickness and increase the nitrogen concentration of the germanium oxynitride layer by removing at least a portion of the oxygen species soluble in H 2 O.

16. The method according to claim 15 , wherein the nitrogen species insoluble in H 2 O include Ge 3 N 4 , the oxygen species soluble in H 2 O include GeO 2 , the nitrogen species soluble in H 2 O include GeN, and the oxygen species insoluble in H 2 O include GeO.

17. The method according to claim 15 , wherein the plasma is generated by a radial line slot antenna plasma source.

18. A method for forming a dielectric layer of a semiconductor device, the method comprising:

providing a germanium-containing dielectric layer containing a greater amount of nitrogen species insoluble in H 2 O than nitrogen species soluble in H 2 O and a greater amount of oxygen species soluble in H 2 O than oxygen species insoluble in H 2 O; and

exposing the germanium-containing dielectric layer to liquid H 2 O or gaseous H 2 O to alter the thickness and the chemical composition of the germanium-containing dielectric layer.

19. The method according to claim 18 , wherein the germanium-containing dielectric layer is a germanium nitride layer, a germanium oxynitride layer, a silicon germanium nitride layer, a silicon germanium oxynitride layer, or a mixture of germanium and a high-k material.

20. The method according to claim 19 , wherein the high-k material comprises Ta 2 O 5 , TiO 2 , ZrO 2 , HfO 2 , Al 2 O 3 , Y 2 O 3 , HfSiO x , ZrSiO x , TaSiO x , SrO x , SrSiO x , LaO x , LaSiO x , YO x , or YSiO x , or a combination of two or more thereof.

21. The method according to claim 18 , wherein the nitrogen species insoluble in H 2 O include Ge 3 N 4 , the oxygen species soluble in H 2 O include GeO 2 , the nitrogen species soluble in H 2 O include GeN, and the oxygen species insoluble in H 2 O include GeO.

22. A method for forming a dielectric layer of a semiconductor device, the method comprising:

providing a germanium-containing substrate in a process chamber;

generating a plasma from a process gas containing N 2 and a noble gas, and selecting the plasma conditions effective to form plasma excited N 2 species while suppressing formation of plasma excited N species, wherein the plasma excited N 2 species comprise N 2 + ions and N 2 radicals, and the plasma excited N species comprise N radicals;

exposing the germanium-containing substrate to the plasma to form a germanium-containing oxynitride layer on the germanium-containing substrate, wherein the germanium-containing oxynitride layer contains a greater amount of Ge 3 N 4 , which is insoluble in H 2 O, than GeN, which is soluble in H 2 O, and a greater amount of GeO 2 , which is soluble in H 2 O, than GeO, which is insoluble in H 2 O; and

exposing the germanium-containing oxynitride layer to liquid H 2 O or gaseous H 2 O to reduce the thickness of the germanium-containing oxynitride layer and to remove at least a portion of the GeN and GeO 2 to thereby increase the nitrogen concentration in the germanium-containing oxynitride layer.

23. The method according to claim 22 , wherein the plasma is generated by a radial line slot antenna plasma source.