Remote plasma activated nitridation
View Patent ↗A nitrogen precursor that has been activated by exposure to a remotely excited species is used as a reactant to form nitrogen-containing layers. The remotely excited species can be, e.g., N 2 , Ar, and/or He, which has been excited in a microwave radical generator. Downstream of the microwave radical generator and upstream of the substrate, the flow of excited species is mixed with a flow of NH 3 . The excited species activates the NH 3 . The substrate is exposed to both the activated NH 3 and the excited species. The substrate can also be exposed to a precursor of another species to form a compound layer in a chemical vapor deposition. In addition, already-deposited layers can be nitrided by exposure to the activated NH 3 and to the excited species, which results in higher levels of nitrogen incorporation than plasma nitridation using excited N 2 alone, or thermal nitridation using NH 3 alone, with the same process temperatures and nitridation durations.
1. A method for semiconductor processing, comprising:
providing a single substrate reaction chamber in gas communication with a source of NH 3 and in gas communication with an excited species generator;
providing a semiconductor substrate in the reaction chamber;
generating an excited species in the excited species generator;
exposing the NH 3 to the excited species upstream of the substrate and downstream of the excited species generator;
exposing the substrate to the NH 3 and the excited species after exposing the NH 3 to the excited species; and
providing energy from the substrate to locally generate radicals from the NH 3 and the excited species near the substrate.
2. The method of claim 1 , wherein precursor for the excited species is N 2 .
3. The method of claim 2 , wherein precursor for the excited species further comprises one or more species chosen from the group consisting of He and Ar.
4. The method of claim 1 , wherein precursor for the excited species is one or more species chosen from the group consisting of He and Ar.
5. The method of claim 1 , wherein exposing the NH 3 to the excited species comprises merging a flow of the excited species and a flow of the NH 3 to form a merged flow of NH 3 and excited species to the substrate.
6. The method of claim 5 , wherein merging the flow comprises flowing the excited species and the NH 3 into the chamber via separate inlets, wherein the flow of the excited species and the flow of the NH 3 converge inside the chamber upstream of the substrate.
7. The method of claim 1 , wherein exposing the NH 3 to the excited species activates the NH 3 to produce nitrogen radicals.
8. The method of claim 7 , wherein generating the excited species produces radicals, wherein exposing the NH 3 to the excited species produces an increase in a total number of radicals relative to an amount of radicals produced after generating the excited species.
9. The method of claim 1 , wherein exposing the substrate comprises nitriding the substrate.
10. The method of claim 9 , wherein a surface of the substrate comprises a dielectric layer, wherein nitriding the substrate comprises nitriding the dielectric layer.
11. The method of claim 10 , wherein the dielectric layer comprises SiO 2 .
12. The method of claim 10 , wherein the dielectric layer comprises a high k dielectric.
13. The method of claim 12 , wherein the high k dielectric is a metal silicate.
14. The method of claim 13 , wherein the metal silicate is HfSiO.
15. The method of claim 12 , wherein the high k dielectric is HfAlO.
16. The method of claim 10 , wherein nitriding the dielectric layer forms a gate dielectric layer for a transistor.
17. The method of claim 9 , wherein nitriding the substrate forms a dielectric layer.
18. The method of claim 17 , wherein nitriding the substrate forms a silicon nitride.
19. The method of claim 9 , further comprising annealing the substrate after nitriding the substrate.
20. The method of claim 19 , wherein annealing the substrate comprises exposing the substrate to an elevated temperature in an inert atmosphere.
21. The method of claim 20 , wherein the inert atmosphere comprises nitrogen gas.
22. The method of claim 20 , wherein the elevated temperature is about 800° C. or less.
23. The method of claim 22 , wherein the elevated temperature is about 700° C. or less.
24. The method of claim 19 , wherein annealing the substrate is performed for about 1-2 minutes.
25. The method of claim 1 , further comprising exposing the substrate to a flow of an other precursor species simultaneous with exposing the substrate to the NH 3 and the excited species, thereby forming a compound film.
26. The method of claim 25 , wherein the other precursor species is a silicon precursor.
27. The method of claim 26 , wherein the silicon precursor is a silane.
28. The method of claim 26 , wherein the silane is SiH 4 .
29. The method of claim 1 , further comprising exposing the substrate to a flow of an other precursor species and removing the other precursor species from the reaction chamber before exposing the substrate to the NH 3 and the excited species.
30. The method of claim 29 , wherein the other precursor species comprises trisilane.
31. The method of claim 1 , wherein generating the excited species comprises exposing the excited species precursor to microwave energy in a microwave radical generator disposed upstream of the reaction chamber.
32. The method of claim 1 , wherein reaction chamber is a laminar flow reaction chamber.
33. The method of claim 1 , wherein forming the merged flow is performed in the reaction chamber.
34. The method of claim 1 , wherein exposing the substrate is performed at about 650° C. or less.
35. The method of claim 34 , wherein exposing the substrate is performed at about 600° C. or less.
36. A method of nitriding a dielectric layer comprising:
providing the a partially fabricated integrated circuit having a dielectric layer in a reaction chamber;
providing a source of excited nitrogen species outside of the reaction chamber;
flowing the excited nitrogen species into the reaction chamber;
flowing ammonia to the reaction chamber separately from the excited nitrogen species;
exposing the ammonia to the excited nitrogen species; and
subsequently nitriding the dielectric layer by exposing the dielectric layer to the excited nitrogen species and ammonia, wherein a nitrogen incorporation is greater than about 5%.
37. The method of claim 36 , wherein nitrogen incorporation is greater than about 10%.
38. The method of claim 37 , wherein nitrogen incorporation is greater than about 15%.
39. The method of claim 36 , wherein nitriding the substrate is performed at about 600° C. or less.
40. The method of claim 36 , wherein the excited nitrogen species comprises nitrogen radicals.
41. The method of claim 36 , wherein the reaction chamber is a single substrate reaction chamber.
42. The method of claim 36 , wherein nitriding the substrate comprises nitriding a dielectric layer.
43. A method for semiconductor processing, comprising:
generating an excited species outside a reaction chamber;
providing a flow of ammonia to the reaction chamber, the flow separate from the excited species;
generating nitrogen radicals in a reaction chamber by exposing ammonia to the excited species; and
nitriding a gate dielectric layer by exposing the gate dielectric layer to the nitrogen radicals.
44. The method of claim 43 , wherein generating nitrogen radicals comprises separately flowing the excited species and the ammonia into the reaction chamber.
45. The method of claim 43 , further comprising forming a gate electrode over the gate dielectric layer.
46. The method of claim 43 , further comprising chemical vapor depositing a compound film on a substrate by exposing the substrate to the nitrogen radicals and an other precursor.
47. The method of claim 46 , wherein the other precursor is a silane and the film is a silicon nitride film.
48. The method of claim 43 , wherein the generating the excited species comprises flowing a gas through a radical generator.
49. The method of claim 47 , wherein the radical generator is a microwave radical generator.
50. The method of claim 47 , wherein the gas is selected from the group consisting of nitrogen gas, helium gas and argon gas.
51. The method of claim 43 , wherein the reaction chamber is a cold wall, single substrate reaction chamber.