Metal gate structures and methods for forming thereof

1. A method for forming a metal gate structure on a substrate having a feature formed in a high k dielectric layer, comprising:

depositing a first layer within the feature atop the dielectric layer;

depositing a second layer comprising cobalt or nickel within the feature atop the first layer; and

depositing a third layer comprising a metal within the feature atop the second layer to fill the feature, wherein at least one of the first or second layers forms a wetting layer to form a nucleation layer for a subsequently deposited layer, wherein one of the first, second, or third layers forms a work function layer, and wherein the third layer forms a metal gate electrode.

2. The method of claim 1 , wherein the dielectric layer comprises one of hafnium silicon oxide (HfSiO), hafnium silicon nitride (HfSiN), aluminum silicon oxynitride (AlSiON), hafnium oxide (HfO), zirconium oxide (ZrO), lanthanum oxide (LaO), aluminum oxide (AlO).

3. The method of claim 1 , wherein forming the metal gate structure comprises forming a pMOS metal gate structure, and wherein depositing the first layer comprises depositing a layer comprising one of titanium (Ti), tantalum (Ta), titanium nitride (TiN), or tantalum nitride (TaN).

4. The method of claim 3 , wherein the first layer forms at least one of a barrier layer or work function layer.

5. The method of claim 1 , wherein forming the metal gate structure comprises forming a pMOS metal gate structure, and wherein depositing the second layer comprising cobalt (Co) or nickel (Ni) comprises depositing the second layer to a thickness of about 5 to about 70 Å.

6. The method of claim 1 , wherein forming the metal gate structure comprises forming an nMOS structure, and wherein depositing the first layer comprises depositing a layer comprising one of manganese (Mn), hafnium (Hf), titanium (Ti), tantalum (Ta), aluminum alloys thereof, titanium nitride (TiN), or tantalum nitride (TaN).

7. The method of claim 6 , wherein the first layer forms at least one of a barrier layer or work function layer.

8. The method of claim 1 , wherein forming the metal gate structure comprises forming an nMOS structure, and wherein the second layer comprising cobalt (Co) or nickel (Ni) is deposited to a thickness of less than about 20 Å.

9. The method of claim 1 , wherein depositing the third layer comprises depositing a metal gate layer comprising aluminum (Al), tungsten (W), cobalt (Co), copper (Cu), or nickel (Ni).

10. The method of claim 1 , wherein depositing the third layer comprises:

depositing a first sublayer comprising aluminum (Al) via chemical vapor deposition;

depositing a second sublayer comprising aluminum (Al) via physical vapor deposition, wherein depositing the second sublayer causes a reflow of the first sublayer, and wherein the first sublayer and second sublayer form a metal gate layer.

11. A method for forming a metal gate structure on a substrate having a feature formed in a high k dielectric layer, comprising:

depositing a first layer within the feature atop the dielectric layer, wherein the first layer is a barrier layer;

depositing a second layer within the feature atop the first layer, wherein the second layer acts as a work function layer and a wetting layer to form a nucleation layer for a subsequently deposited layer; and

depositing a third layer comprising aluminum (Al) within the feature atop the second layer to fill the feature, wherein the third layer forms a metal gate electrode.

12. The method of claim 11 , wherein the first layer comprises titanium nitride or tantalum nitride.

13. The method of claim 11 , wherein the second layer comprises at least one of tantalum, titanium, hafnium, and their alloys with aluminum.