Surface depassivation with thermal etch after nitrogen radical treatment

1 . A method of forming a structure on a substrate, comprising:

exposing at least one opening formed in a multi-tier portion of the substrate to a tungsten-containing gas at a precursor gas flow rate;

exposing the at least one opening of the substrate to a reducing agent at a reducing agent flow rate, wherein the tungsten-containing gas and the reducing agent are alternated cyclically to form a nucleation layer within the at least one opening of the substrate;

exposing the at least one opening of the substrate to a nitrogen-containing gas to inhibit growth of the nucleation layer at narrow portions within the at least one opening,

exposing the at least one opening of the substrate to the tungsten-containing gas to form a fill layer over the nucleation layer within the at least one opening; and

exposing the at least one opening to a molybdenum-containing gas to remove a desired amount of a tungsten nitride passivation layer from the fill layer.

2 . The method of claim 1 , wherein the molybdenum-containing gas is selected from the group consisting of molybdenum halides, molybdenum oxyhalides, and combinations thereof.

3 . The method of claim 2 , wherein exposing the at least one opening to a molybdenum-containing gas to remove a desired amount of a tungsten nitride passivation layer from the fill layer comprises flowing the molybdenum-containing gas at a first flow rate to produce a first etch rate.

4 . The method of claim 3 , wherein the first etch rate is proportional to the first flow rate of the molybdenum-containing gas.

5 . The method of claim 4 , wherein exposing the at least one opening of the substrate to a molybdenum-containing gas includes flowing the molybdenum-containing gas for a period ranging from about 1 second to about 30 seconds.

6 . The method of claim 1 , further comprising exposing the at least one opening of the substrate to a nitrogen-containing plasma to inhibit growth of the fill layer along the at least one opening.

7 . The method of claim 6 , further comprising determining sequence, time of exposure, and ratio of gas flow between the nitrogen-containing gas and the nitrogen-containing plasma based on a profile of the at least one opening.

8 . A method of forming a structure on a substrate, comprising:

exposing at least one opening formed within the substrate to a tungsten-containing precursor gas at a precursor gas flow rate, wherein the at least one opening comprises a lower portion and an upper portion, wherein the upper portion comprises a width smaller than a width of the lower portion;

exposing the at least one opening of the substrate to a reducing agent at a reducing agent flow rate, wherein the tungsten-containing precursor gas and the reducing agent are alternated cyclically to form a nucleation layer within the at least one opening of the substrate;

exposing the at least one opening of the substrate to the tungsten-containing precursor gas to form a fill layer over the nucleation layer within the at least one opening;

exposing the at least one opening of the substrate to a nitrogen-containing gas;

exposing the at least one opening of the substrate to a molybdenum-containing gas to remove a tungsten nitride passivation layer from the fill layer on the at least one opening; and

exposing the at least one opening of the substrate to the tungsten-containing precursor gas to form the fill layer within the at least one opening.

9 . The method of claim 8 , wherein the molybdenum-containing gas is selected from the group consisting of molybdenum halides, molybdenum oxyhalides, and combinations thereof.

10 . The method of claim 8 , wherein the at least one opening further comprises a middle portion between the upper portion and the lower portion, wherein the middle portion comprises a width smaller than the width of the upper portion and the width of the lower portion.

11 . The method of claim 10 , further comprising exposing the at least one opening of the substrate to the nitrogen-containing gas or a nitrogen-containing plasma to inhibit growth of the fill layer along the at least one opening.

12 . The method of claim 10 , wherein the substrate comprises an upper tier layer and a lower tier layer interfacing the upper tier layer at an interface, wherein a width of the at least one opening within the upper tier layer at the interface is narrower than a width of the at least one opening within the lower tier layer at the interface.

13 . The method of claim 10 , wherein exposing the at least one opening of the substrate to a molybdenum-containing gas includes flowing the molybdenum-containing gas for a period ranging from about 1 second to about 30 seconds.

14 . The method of claim 10 , wherein exposing the at least one opening of the substrate to a nitrogen-containing gas includes flowing the nitrogen-containing gas at a rate of about 0.5 sccm to about 500 sccm.

15 . The method of claim 10 , wherein the nitrogen-containing gas is selected from the group consisting of NF 3 , NH 3 , N 2 H 4 , and combinations thereof.

16 . A method of forming a structure on a substrate, comprising:

forming a tungsten nucleation layer within at least one opening formed in a multi-tier portion of the substrate;

exposing the tungsten nucleation layer to a nitrogen-containing plasma to inhibit growth of the tungsten nucleation layer at narrow portions within the at least one opening;

exposing the at least one opening to a tungsten-containing precursor gas to form a fill layer over the nucleation layer within the at least one opening;

exposing the at least one opening of the substrate to a nitrogen-containing gas to inhibit growth of the fill layer along the at least one opening; and

exposing the at least one opening to a molybdenum-containing gas to remove a tungsten nitride passivation layer from the fill layer on the at least one opening.

17 . The method of claim 16 , further comprising before exposing the at least one opening of the substrate to the nitrogen-containing gas, forming a second nucleation layer over the fill layer.

18 . The method of claim 17 , further comprising after exposing the at least one opening of the substrate to the nitrogen-containing gas, exposing the at least one opening to a molybdenum-containing gas to remove a tungsten nitride passivation layer from the tungsten nucleation layer on the at least one opening and then forming a second fill layer within the at least one opening.

19 . The method of claim 18 , further comprising exposing the second fill layer within the at least one opening to the nitrogen-containing gas or the nitrogen-containing plasma to inhibit growth of the second fill layer.

20 . The method of claim 19 , further comprising exposing the at least one opening to a molybdenum-containing gas to remove a tungsten nitride passivation layer from the second fill layer on the at least one opening then forming a third fill layer within the at least one opening.