Treatment of tungsten surface for tungsten gap-fill

1 . A method of filling a feature on a substrate, comprising:

performing a gradient oxidation process to oxidize exposed portions of a tungsten-containing liner layer, thereby forming tungsten oxide on the tungsten-containing liner layer,

wherein the gradient oxidation process preferentially oxidizes an overhang portion of the tungsten-containing liner layer, which obstructs or blocks top openings of one or more features formed within a field region of a substrate;

performing an etchback process to reduce the oxidized overhang portion of the tungsten-containing liner layer;

exposing the tungsten-containing liner layer to a chemical vapor transport (CVT) process to remove the tungsten oxide remaining on the tungsten-containing liner layer, wherein the CVT process comprises exposing the tungsten-containing liner layer to an inductively coupled plasma (ICP) comprising hydrogen and oxygen; and

performing a tungsten gap-fill process to fill or partially fill the one or more features.

2 . The method of claim 1 , wherein the CVT process reduces the tungsten oxide to tungsten.

3 . The method of claim 1 , wherein exposing the tungsten-containing liner layer to the ICP is performed at a temperature of 400 degrees Celsius or less and comprises supplying a processing gas comprising greater than or equal to 90% of hydrogen gas of a total flow of hydrogen gas and oxygen gas.

4 . The method of claim 3 , wherein performing the gradient oxidation process, performing the etchback process, and exposing the tungsten-containing liner layer to the CVT process are performed in a processing chamber without breaking vacuum.

5 . The method of claim 4 , wherein the one or more features comprise a bottom surface and at least one sidewall and the tungsten-containing liner layer is formed over the at least one sidewall and the bottom surface.

6 . A method of filling a feature formed on a substrate, comprising:

depositing one or more tungsten-containing layers over a surface of a substrate, wherein

the substrate comprises one or more features formed within a field region of the surface of the substrate,

each of the one or more features comprises a sidewall surface and a bottom surface, and

the one or more tungsten-containing layers are formed over the field region, the sidewall surface, and the bottom surface of the one or more features;

exposing the surface of the substrate to a gradient oxidizing process, wherein the gradient oxidizing process forms preferentially oxidized regions of the tungsten-containing layers that are disposed over the field region of the one or more features;

preferentially etching the preferentially oxidized regions of the one or more tungsten-containing layers formed on the surface of the substrate, wherein, after performing the process of preferentially etching the preferentially oxidized regions, a first portion of the one or more tungsten-containing layers remains on the bottom surface of each of the one or more features and a second portion of the one or more tungsten-containing layers remains on the sidewall surface of each of the one or more features;

exposing at least the second portion of the one or more tungsten-containing layers to a post-etch treatment process to reduce oxidized tungsten to tungsten and remove contaminants from surfaces of the one or more tungsten-containing layers, wherein the post-etch treatment process comprises exposing the tungsten-containing layers to a hydrogen and oxygen inductively coupled plasma treatment; and

filling the one or more features with a second tungsten layer, wherein the process of filling the one or more features with the second tungsten layer comprises preferentially growing the second tungsten layer from the second portion of the one or more tungsten-containing layers on the sidewall surface and the first portion of the one or more tungsten-containing layers that remain on the bottom surface of each of the one or more features.

7 . The method of claim 6 , wherein the post-etch treatment process further comprises exposing the tungsten-containing layers to argon.

8 . The method of claim 6 , wherein the hydrogen and oxygen inductively coupled plasma treatment is performed at temperatures of 400 degrees Celsius or less and comprises supplying a processing gas comprising greater than or equal to 90% of hydrogen gas of a total flow of hydrogen gas and oxygen gas.

9 . The method of claim 8 , wherein the sidewall surface is defined by a dielectric material selected from silicon oxide, silicon nitride, silicon oxynitride, or a combination thereof.

10 . The method of claim 9 , wherein depositing the one or more tungsten-containing layers over the surface of the substrate, comprises:

depositing a tungsten liner layer over the one or more features via a physical vapor deposition process; and

depositing a boron-tungsten nucleation layer over the tungsten liner layer via an atomic layer deposition (ALD) process.

11 . The method of claim 10 , wherein filling the one or more features with the second tungsten layer comprises a chemical vapor deposition (CVD) gap-fill process.

12 . The method of claim 6 , wherein exposing the surface of the substrate to the gradient oxidizing process, preferentially etching the preferentially oxidized regions of the one or more tungsten-containing layers formed on the surface of the substrate, and exposing at least the second portion of the one or more tungsten-containing layers to the post-etch treatment process are performed in a first process chamber disposed on a cluster tool.

13 . A method of filling a feature formed on a substrate, comprising:

depositing one or more tungsten-containing layers over a surface of a substrate, wherein

the substrate comprises one or more features formed within a field region of the surface of the substrate,

each of the one or more features comprises a sidewall surface and a bottom surface, and

the one or more tungsten-containing layers are formed over the field region, the sidewall surface, and the bottom surface of the one or more features;

exposing the surface of the substrate to a gradient oxidizing process, wherein the gradient oxidizing process forms preferentially oxidized regions of the tungsten-containing layers that are disposed over the field region of the one or more features;

preferentially etching the preferentially oxidized regions of the one or more tungsten-containing layers formed on the surface of the substrate, wherein, after performing the process of preferentially etching the preferentially oxidized regions, a first portion of the one or more tungsten-containing layers remains on the bottom surface of each of the one or more features and a second portion of the one or more tungsten-containing layers remains on the sidewall surface of each of the one or more features;

exposing at least the second portion of the one or more tungsten-containing layers to a post-etch treatment process to reduce oxidized tungsten to tungsten and remove contaminants from surfaces of the one or more tungsten-containing layers,

wherein the post-etch treatment process comprises a chemical vapor transport (CVT) process, the CVT process comprising a volatilization process and a reduction process, and the volatilization process proceeds via the following reaction (I) WO2+2H2O→WO2 (OH) 2+H2 and the reduction process proceeds via the following reaction (II) WO2 (OH) 2+3H2→W+4H2O; and

filling the one or more features with a second tungsten layer, wherein the process of filling the one or more features with the second tungsten layer comprises preferentially growing the second tungsten layer from the second portion of the one or more tungsten-containing layers on the sidewall surface and the first portion of the one or more tungsten-containing layers that remain on the bottom surface of each of the one or more features.

14 . The method of claim 13 , wherein the gradient oxidation process, the etching, and the post-etch treatment process are performed in a processing chamber without breaking vacuum.

15 . The method of any of claim 13 , wherein the sidewall surface is defined by a dielectric material selected from silicon oxide, silicon nitride, silicon oxynitride, or a combination thereof.

16 . The method of claim 15 , wherein depositing the one or more tungsten-containing layers over the surface of the substrate, comprises:

depositing a tungsten liner layer over the one or more features via a physical vapor deposition process; and

depositing a boron-tungsten nucleation layer over the tungsten liner layer via an atomic layer deposition (ALD) process.

17 . The method of claim 16 , wherein filling the one or more features with the second tungsten layer comprises a chemical vapor deposition (CVD) gap-fill process.

18 . The method of claim 13 , wherein exposing the surface of the substrate to the gradient oxidizing process, preferentially etching the preferentially oxidized regions of the one or more tungsten-containing layers formed on the surface of the substrate, and exposing at least the second portion of the one or more tungsten-containing layers to the post-etch treatment process are performed in a first process chamber disposed on a cluster tool.

19 . The method of claim 13 , wherein the volatilization process and the reduction process of the chemical vapor transport (CVT) process are performed cyclically to recover a conductive tungsten surface by removing surface contaminants comprising one or more of fluorine, boron, and nitrogen prior to filling the one or more features with the second tungsten layer.

20 . The method of claim 19 , wherein, after the etchback process and prior to filling the one or more features with the second tungsten layer, the post-etch treatment reduces impurity levels of the surface contaminants comprising one or more of fluorine, boron, and nitrogen on the tungsten-containing layers.