Treatment of tungsten surface for tungsten gap-fill

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.

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.