Methods of forming silicon nitride by atomic layer deposition and methods of forming semiconductor structures

1. A method of forming silicon nitride, comprising:

forming silicon nitride on a substrate by atomic layer deposition at a temperature of less than or equal to about 275° C., the silicon nitride formed by contacting a silicon precursor and a nitrogen precursor with the substrate, the silicon precursor comprising a brominated silane, a silylene compound, or combinations thereof; and

exposing the as-formed silicon nitride to a plasma.

2. The method of claim 1 , wherein forming silicon nitride on a substrate by atomic layer deposition comprises forming the silicon nitride in a plasma-free environment.

3. The method of claim 1 , wherein forming silicon nitride on a substrate by atomic layer deposition comprises forming the silicon nitride by atomic layer deposition at a temperature of from about 90° C. to about 275° C.

4. The method of claim 1 , wherein forming silicon nitride on a substrate by atomic layer deposition comprises forming the silicon nitride by atomic layer deposition at a temperature of from about 200° C. to about 275° C.

5. The method of claim 1 , wherein forming silicon nitride on a substrate by atomic layer deposition comprises forming the silicon nitride by atomic layer deposition at a temperature of from about 200° C. to about 250° C.

6. The method of claim 1 , wherein contacting a silicon precursor and a nitrogen precursor with the substrate comprises contacting the silicon precursor with a nitrogen precursor comprising ammonia, hydrazine, t-butyl hydrazine, a monoalkylhydrazine, a dialkylhydrazine, or combinations thereof with the substrate.

7. The method of claim 1 , wherein contacting a silicon precursor and a nitrogen precursor with the substrate comprises contacting a silicon precursor comprising silicon tetrabromide or N,N′-di-tert-butyl-1,3-diaza-2-silacyclopent-4-en-2-ylidene and a nitrogen precursor comprising ammonia with the substrate.

8. The method of claim 1 , wherein exposing the as-formed silicon nitride to a plasma comprises exposing the as-formed silicon nitride to a helium plasma, an argon plasma, a xenon plasma, a nitrogen (N 2 ) plasma, a hydrogen (H 2 ) plasma, or combinations thereof.

9. The method of claim 1 , further comprising repeating the forming silicon nitride on a substrate by atomic layer deposition at a temperature of less than or equal to about 275° C. and the exposing the as-formed silicon nitride to a plasma acts to form the silicon nitride to a desired thickness.

10. The method of claim 1 , wherein forming silicon nitride on a substrate by atomic layer deposition at a temperature of less than or equal to about 275° C. comprises forming an entire thickness of the silicon nitride before exposing the as-formed silicon nitride to the plasma.

11. The method of claim 1 , wherein forming silicon nitride on a substrate by atomic layer deposition at a temperature of less than or equal to about 275° C. comprises forming the silicon nitride in a plasma free environment.

12. A method of forming silicon nitride, comprising:

forming a portion of silicon nitride by atomic layer deposition on a substrate, the portion of silicon nitride formed by:

contacting a silicon precursor comprising a brominated silane, a silylene compound, or combinations thereof and a nitrogen precursor comprising ammonia with the substrate;

exposing the portion of silicon nitride to a plasma treatment;

forming at least one other portion of silicon nitride by atomic layer deposition on the portion of silicon nitride, the at least one other portion of silicon nitride formed by:

contacting a silicon precursor comprising a brominated silane, a silylene compound, or combinations thereof and a nitrogen precursor comprising ammonia with the portion of silicon nitride; and

exposing the at least one other portion of silicon nitride to a plasma treatment.

13. The method of claim 12 , wherein forming a portion of silicon nitride by atomic layer deposition comprises forming the portion of silicon nitride to a thickness of at least about 50% of a total thickness of the silicon nitride.

14. The method of claim 12 , wherein forming a portion of silicon nitride by atomic layer deposition comprises forming the portion of silicon nitride to a thickness of from about 80% to about 90% of a total thickness of the silicon nitride.

15. The method of claim 12 , further comprising exposing the substrate to ammonia before forming the portion of silicon nitride by atomic layer deposition on the substrate.

16. The method of claim 12 , wherein forming a portion of silicon nitride by atomic layer deposition on a substrate and forming at least one other portion of silicon nitride by atomic layer deposition on the portion of silicon nitride comprises contacting the silicon precursor and the nitrogen precursor in a plasma-free environment.

17. The method of claim 12 , wherein the silylene compound N,N′-di-tert-butyl-1,3-diaza-2-silacyclopent-4-en-2-ylidene.

18. A method of forming a semiconductor structure, comprising:

forming silicon nitride by atomic layer deposition at a temperature of less than or equal to about 275° C. on at least one feature on a substrate, the silicon nitride formed by contacting a silicon precursor and a nitrogen precursor with the substrate, the silicon precursor comprising a brominated silane, an iodinated silane, a silylene compound, or combinations thereof and the at least one feature having an aspect ratio of greater than about 10:1 on a substrate; and

exposing the as-formed silicon nitride to a plasma.

19. The method of claim 18 , wherein forming silicon nitride by atomic layer deposition at a temperature of less than or equal to about 275° C. on at least one feature on a substrate comprises forming the at least one feature comprising at least one thermally sensitive material on the substrate.

20. The method of claim 18 , wherein forming silicon nitride by atomic layer deposition at a temperature of less than or equal to about 275° C. on at least one feature on a substrate comprises forming the at least one feature comprising at least one of a chalcogenide material, a carbon material, or a reactive metal on the substrate.

21. The method of claim 18 , wherein forming silicon nitride by atomic layer deposition at a temperature of less than or equal to about 275° C. on at least one feature on a substrate comprises forming the at least one feature having an aspect ratio of at about least 12:1.

22. The method of claim 18 , wherein forming silicon nitride by atomic layer deposition at a temperature of less than or equal to about 275° C. on at least one feature on a substrate comprises forming the silicon nitride exhibiting a step coverage of greater than about 85%.

23. The method of claim 22 , wherein forming the silicon nitride exhibiting a step coverage of greater than about 85% comprises forming the silicon nitride exhibiting a step coverage of greater than about 90%.

24. The method of claim 22 , wherein forming silicon nitride by atomic layer deposition at a temperature of less than or equal to about 275° C. on at least one feature on a substrate comprises forming the at least one feature having an aspect ratio of about 12:1.

25. The method of claim 22 , wherein forming silicon nitride by atomic layer deposition at a temperature of less than or equal to about 275° C. on at least one feature on a substrate comprises forming the at least one feature having an aspect ratio of about 15:1.

26. A method of forming silicon nitride, comprising:

forming silicon nitride on a substrate by atomic layer deposition at a temperature of less than or equal to about 275° C., the silicon nitride formed by contacting a silicon precursor comprising a silylene compound and a nitrogen precursor with the substrate; and

exposing the as-formed silicon nitride to a plasma.