Atomic layer etch of tungsten for enhanced tungsten deposition fill
Methods of depositing tungsten into high aspect ratio features using a dep-etch-dep process integrating various deposition techniques with alternating pulses of surface modification and removal during etch are provided herein.
1. A method comprising:
preferentially etching a first amount of a metal in a feature on a substrate at or near an opening of the feature relative to an interior region of the feature by
(i) exposing the feature to a halogen-containing gas to form a modified surface of the first amount of the metal;
(ii) exposing the modified surface to an activation gas; and
(iii) applying a bias to the substrate during at least one of (i) and (ii) using a bias power.
2. The method of claim 1 , wherein the metal contains tungsten or molybdenum.
3. The method of claim 1 , wherein the bias power when applied during (i) is greater than OV and less than about 200 V.
4. The method of claim 1 , wherein the bias power when applied during (ii) is less than a threshold bias power.
5. The method of claim 1 , wherein the forming of the modified surface of the first amount of the metal is self-limiting.
6. The method of claim 1 , further comprising depositing the first amount of the metal in the feature on the substrate, wherein the depositing and the preferentially etching are performed without breaking vacuum.
7. The method of claim 6 , wherein the depositing and the preferentially etching are performed in different chambers of the same tool.
8. The method of claim 1 , further comprising igniting a plasma during at least one of (i) and (ii).
9. The method of claim 1 , further comprising, after preferentially etching the first amount of the metal, depositing a second amount of metal in the feature.
10. The method of claim 9 , wherein the metal is tungsten deposited using one or more tungsten precursors or combinations thereof.
11. The method of claim 9 , wherein the metal is selected from the group consisting of fluorine-free tungsten, titanium, tantalum, nickel, and cobalt.
12. The method of claim 1 , wherein the halogen-containing gas is selected from the group consisting of chlorine, bromine, iodine, and combinations thereof.
13. The method of claim 1 , wherein the activation gas is selected from a group consisting of helium, neon, krypton, and argon.
14. A method comprising:
preferentially etching a first amount of a metal in a feature on a substrate at or near an opening of the feature relative to an interior region of the feature by
(i) exposing the feature to a halogen-containing gas to form a modified surface of the first amount of the metal; and
(ii) exposing the modified surface to an activation gas at a chamber pressure between about 1 mTorr and about 15 mTorr.
15. The method of claim 14 , wherein the metal contains tungsten or molybdenum.
16. The method of claim 14 , wherein forming of the modified surface of the first amount of the metal comprises a self-limiting reaction.
17. The method of claim 14 , further comprising depositing the first amount of the metal in the feature on the substrate, wherein the depositing and the preferentially etching are performed without breaking vacuum.
18. The method of claim 14 , further comprising igniting a plasma during at least one of (i) and (ii).
19. The method of claim 14 , further comprising, after preferentially etching the first amount of the metal, depositing a second amount of metal in the feature.