Gate structures in semiconductor devices

1 . A method, comprising:

forming nanostructured channel regions;

forming gate openings surrounding the nanostructured channel regions;

forming oxide layers on exposed surfaces of the nanostructured channel regions in the gate openings;

depositing, on the oxide layers, a diffusion barrier layer comprising a layer of metal oxide;

depositing, on and in contact with the diffusion barrier layer, a first dielectric layer comprising a high-k dielectric material;

performing a doping process on the diffusion barrier layer and the first dielectric layer to form a doped diffusion barrier layer and a doped dielectric layer; and

depositing a conductive layer on the doped dielectric layer.

2 . The method of claim 1 , wherein forming the oxide layers comprises performing a wet oxidation process on the exposed surfaces of the nanostructured channel regions.

3 . The method of claim 1 , wherein forming the oxide layers comprises oxidizing the exposed surfaces of the nanostructured channel regions in a solution mixture of diluted hydrochloric acid (HCl), hydrogen peroxide (H 2 O 2 ), and deionized (DI) water.

4 . The method of claim 1 , wherein forming the oxide layers comprises performing a wet oxidation process with a solution mixture of diluted hydrochloric acid (HCl), hydrogen peroxide (H 2 O 2 ), and deionized (DI) water in a volumetric ratio of about 1:1:50 to about 2:1:100.

5 . The method of claim 1 , wherein depositing the diffusion barrier layer comprises depositing the layer of metal oxide with a Gibbs free energy of formation lower than that of a metal oxide of the first dielectric layer.

6 . The method of claim 1 , wherein depositing the diffusion barrier layer comprises depositing the layer of metal oxide with a Gibbs free energy of formation lower than that of hafnium oxide.

7 . The method of claim 1 , wherein performing the doping process comprises depositing, on the first dielectric layer, a dopant source layer with a metal oxide that is different from a metal oxide of the diffusion barrier layer.

8 . The method of claim 1 , wherein performing the doping process comprises:

depositing a dopant source layer on the first dielectric layer; and

performing an anneal process on the dopant source layer.

9 . The method of claim 1 , wherein performing the doping process comprises:

depositing a rare-earth metal-based dopant source layer on the first dielectric layer; and

performing an anneal process on the rare-earth metal-based dopant source layer.

10 . The method of claim 1 , further comprising depositing a second dielectric layer on the doped dielectric layer prior to depositing the conductive layer.

11 . A method, comprising:

forming first and second nanostructured channel regions;

forming first and second gate openings surrounding the first and second nanostructured channel regions, respectively;

performing an oxidation process on exposed surfaces of the first and second nanostructured channel regions in the first and second gate openings, respectively;

depositing a diffusion barrier layer with first and second barrier portions in the first and second gate openings, respectively;

performing a doping process on the first and second barrier portions to form first and second doped barrier portions with first and second metal dopants, respectively, wherein performing the doping process comprises:

depositing, on the first barrier portion, a first dopant source layer with a first metal oxide that is different from a metal oxide of the diffusion barrier layer; and

depositing, on the second barrier portion, a second dopant source layer with a second metal oxide that is different from the first metal oxide and the metal oxide of the diffusion barrier layer; and

depositing a conductive layer on the first and second doped barrier portions.

12 . The method of claim 11 , wherein performing the oxidation process comprises oxidizing the exposed surfaces of the first and second nanostructured channel regions in a solution mixture of diluted hydrochloric acid (HCl), hydrogen peroxide (H 2 O 2 ), and deionized (DI) water.

13 . The method of claim 11 , wherein performing the oxidation process comprises performing a wet oxidation process with a solution mixture of diluted hydrochloric acid (HCl), hydrogen peroxide (H 2 O 2 ), and deionized (DI) water in a volumetric ratio of about 1:1:50 to about 2:1:100.

14 . The method of claim 11 , further comprising depositing a high-k dielectric layer on the diffusion barrier layer prior to performing the doping process.

15 . The method of claim 14 , wherein depositing the diffusion barrier layer comprises depositing a layer of metal oxide with a Gibbs free energy of formation lower than that of a metal oxide of the high-k dielectric layer.

16 . The method of claim 11 , wherein performing the doping process comprises:

performing a first anneal process after depositing the first and second dopant source layers;

removing the first and second dopant source layers; and

performing a second anneal process on the first and second doped barrier portions after removing the first and second dopant source layers.

17 . A method, comprising:

depositing an oxide layer on a channel region;

depositing a diffusion barrier layer on the oxide layer;

depositing a high-k dielectric layer on the diffusion barrier layer;

performing a doping process on the diffusion barrier layer and the high-k dielectric layer to form a doped diffusion barrier layer with a first dopant concentration and a doped high-k dielectric layer with a second dopant concentration lower than the first dopant concentration; and

depositing a conductive layer on the doped high-k dielectric layer.

18 . The method of claim 17 , wherein performing the doping process comprises doping the diffusion barrier layer and the high-k dielectric layer with metal dopants.

19 . The method of claim 17 , wherein performing the doping process comprises depositing, on the high-k dielectric layer, a dopant source layer with a metal oxide that is different from a metal oxide of the diffusion barrier layer.

20 . The method of claim 17 , wherein performing the doping process comprises:

depositing a dopant source layer on the high-k dielectric layer;

performing a first anneal process on the dopant source layer;

removing the dopant source layer; and

performing a second anneal process on the doped high-k dielectric layer after removing the dopant source layer.