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 a direct or remote plasma. Pre-inhibition and post-inhibition treatments are used to modulate the inhibition effect, facilitating feature fill using inhibition across a wide process window. The methods described herein can be used to fill vertical features, such as in tungsten vias, and horizontal features, such as vertical NAND (VNAND) wordlines. The methods may be used for both conformal fill and bottom-up/inside-out fill. Examples of applications include logic and memory contact fill, DRAM buried wordline fill, vertically integrated memory gate and wordline fill, and 3-D integration using through-silicon vias.
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,
after selectively inhibiting tungsten nucleation in the feature and prior to selectively depositing tungsten in the feature, modulating the differential inhibition profile to form a modified differential inhibition profile, wherein modulating the differential inhibition profile comprises raising the substrate temperature to an anneal temperature, maintaining the substrate in an inert or oxidizing environment at the anneal temperature to thermally anneal the substrate; and
selectively depositing tungsten in the feature in accordance with the modified differential inhibition profile, wherein selectively depositing tungsten in the feature comprises inletting a tungsten-containing precursor to a chamber containing the substrate and wherein modulating the differential inhibition profile is performed prior to inletting the tungsten-containing precursor into the chamber.
2. The method of claim 1 , wherein selectively inhibiting tungsten nucleation in the feature comprises exposing the feature to a direct plasma while applying a bias to the substrate.
3. The method of claim 2 , wherein the plasma contains one or more of nitrogen, hydrogen, oxygen and carbon activated species.
4. The method of claim 2 , wherein the plasma is nitrogen-based and/or hydrogen-based.
5. The method of claim 1 , wherein selectively inhibiting tungsten nucleation in the feature comprises exposing the feature to a remotely-generated plasma.
6. The method of claim 1 , further comprising depositing a tungsten layer in the feature prior to selective inhibition.
7. The method of claim 1 , wherein modulating the differential inhibition profile comprises thermally annealing the substrate by raising the substrate temperature at least 50° C.
8. The method of claim 1 , wherein modulating the differential inhibition profile comprises exposing the feature to a hydrogen-containing plasma.
9. The method of claim 1 , further comprising, after selectively depositing tungsten in the feature, non-selectively depositing tungsten in the feature.
10. The method of claim 9 , wherein transitioning from selective to non-selective deposition comprises allowing a CVD process to continue without deposition of an intervening tungsten nucleation layer.
11. The method of claim 10 , wherein transitioning from selective to non-selective deposition comprising deposition of a tungsten nucleation layer on the selectively deposited tungsten.
12. The method of claim 1 , wherein selectively inhibiting tungsten nucleation comprises treating a tungsten surface of the feature.
13. The method of claim 1 , wherein selectively inhibiting tungsten nucleation comprises treating a metal nitride surface of the feature.
14. The method of claim 1 , wherein selective inhibition is performed without etching material in the feature.
15. The method of claim 1 , wherein the feature fill is performed without etching material in the feature.
16. The method of claim 1 , wherein modulating the differential inhibition profile comprises thermally annealing the substrate by raising the substrate temperature at least 200° C.
17. The method of claim 1 , wherein modulating the differential inhibition profile comprises reducing an inhibition effect prior to deposition of a tungsten bulk layer in the feature.
18. The method of claim 1 , wherein the selective deposition is performed at a substrate temperature that is different than the anneal temperature.
19. The method of claim 1 , wherein the substrate is annealed for an anneal duration of at least 50 seconds.