Tungsten feature fill with nucleation inhibition
Described herein are methods of filling features with tungsten, and related systems and apparatus, involving inhibition of tungsten nucleation. In some embodiments, the methods involve selective inhibition along a feature profile. Methods of selectively inhibiting tungsten nucleation can include exposing the feature to ammonia vapor in a non-plasma process. Process parameters including exposure time, substrate temperature, and chamber pressure can be used to tune the inhibition profile. Also provided are methods of filling multiple adjacent lines with reduced or no line bending. The methods involve selectively inhibiting the tungsten nucleation to reduce sidewall growth during feature fill.
1. A method comprising:
providing a substrate including a feature having one or more feature openings and a feature interior,
selectively inhibiting tungsten nucleation in the feature such that there is a differential inhibition profile along a feature axis by exposing the feature to ammonia vapor in a non-plasma process; and
selectively depositing tungsten in the feature in accordance with the differential inhibition profile.
2. The method of claim 1 , wherein selectively inhibiting tungsten nucleation in the feature further comprises exposing the feature to a reducing agent and a tungsten-containing precursor.
3. The method of claim 1 , further comprising depositing a tungsten layer in the feature prior to selective inhibition.
4. The method of claim 3 , wherein the tungsten layer is deposited by a pulsed nucleation layer (PNL) process.
5. The method of claim 3 , wherein the tungsten layer is conformally deposited in the feature.
6. The method of claim 1 , wherein selectively depositing tungsten comprises a chemical vapor deposition (CVD) process.
7. The method of claim 1 , further comprising, after selectively depositing tungsten in the feature, depositing tungsten in the feature to complete feature fill.
8. The method of claim 1 , further comprising, after selectively depositing tungsten in the feature, non-selectively depositing tungsten in the feature.
9. The method of claim 1 , wherein selectively inhibiting tungsten nucleation comprises treating a tungsten surface of the feature.
10. The method of claim 1 , wherein selectively inhibiting tungsten nucleation comprises forming a tungsten nitride surface in the feature.
11. The method of claim 1 , wherein selectively inhibiting tungsten nucleation comprises exposing the feature to inhibition species in a mass-transport limited regime.
12. The method of claim 1 , wherein the ammonia vapor is introduced in pulses.
13. The method of claim 12 , wherein the ammonia vapor is introduced as one pulse in a sequence of reactant pulses.
14. The method of claim 1 , wherein the feature has a closed end and wherein the differential inhibition profile is such that the inhibition at the feature surface of the closed end is less than at the feature opening.
15. The method of claim 1 , wherein selectively depositing tungsten comprises an atomic layer deposition (ALD) process.
16. The method of claim 1 , further comprising repeating the selective inhibition and selective deposition operations one or more times.
17. The method of claim 1 , wherein selectively inhibiting tungsten nucleation comprises passivating a surface without forming a compound material.
18. The method of claim 1 , wherein the feature is exposed to ammonia vapor at substrate temperature of from 250° C. to 450° C.
19. The method of claim 1 , wherein the selective inhibition and selective deposition operations are performed in the same chamber.
20. The method of claim 1 , wherein the selective inhibition and selective deposition operations are performed in the different chambers.