Integrated circuits having replacement metal gates with improved threshold voltage performance and methods for fabricating the same

1. A method for fabricating an integrated circuit, the method comprising: providing a bulk dielectric layer overlying a semiconductor substrate, the bulk dielectric layer having a first trench and a second trench; forming a gate dielectric layer in the first trench and the second trench; forming a first barrier layer overlying the gate dielectric layer; forming a work function material layer within the first trench and the second trench; recessing the work function material layer and the first barrier layer in the first trench and the second trench, wherein the work function material layer and the first barrier layer form a chamfered surface relative to and below the top planar surface of the bulk dielectric laver; recessing the gate dielectric layer in the first trench and the second trench; depositing a conductive gate electrode material such that it fills the first trench and the second trench; and recessing the conductive gate electrode material in the first trench and the second trench.

2. The method of claim 1 , further comprising forming a second barrier layer after forming the first barrier layer, wherein the second barrier layer overlies a portion of the first barrier layer in the first trench but is absent from the second trench.

3. The method of claim 2 , wherein forming the second barrier layer comprises:

forming the second barrier layer overlying the first barrier layer;

forming a mask on the second barrier layer;

forming a photoresist on the mask;

patterning the photoresist to form a patterned photoresist;

etching the mask using the patterned photoresist as an etch mask;

removing the second barrier layer from the second trench and a portion of the first trench.

4. The method of claim 3 , wherein forming the second barrier layer comprises forming a titanium nitride layer.

5. The method of claim 1 , wherein providing the dielectric layer comprises providing a hafnium oxide layer and wherein recessing the gate dielectric layer comprises etching gate dielectric layer stringers using a dry plasma etch.

6. The method of claim 1 , wherein depositing the first barrier layer comprises depositing a titanium nitride layer.

7. The method of claim 6 , wherein depositing the first barrier layer comprises depositing a tantalum nitride layer overlying the titanium nitride layer.

8. The method of claim 1 , wherein forming the work function material layer comprises forming titanium aluminum.

9. The method of claim 1 , wherein recessing the work function material layer and the first barrier layer comprises:

depositing a mask material overlying the work function material layer after forming the work function material layer;

forming a patterned photoresist on the mask material;

etching the mask material using the patterned photoresist as an etch mask, wherein the mask material remains in the first trench and the second trench;

removing a portion of the work function material layer using the mask material, the first barrier layer and the gate dielectric layer as an etch mask; and

removing a portion of the first barrier layer using the mask material, the work function material layer, and the gate dielectric layer as an etch mask.

10. The method of claim 1 , wherein depositing the conductive gate electrode material comprises depositing tungsten.

11. The method of claim 1 , wherein providing the bulk dielectric layer overlying the semiconductor substrate comprises providing the bulk dielectric layer overlying a fin structure of a subsequently-formed FinFET device.

12. The method of claim 1 , wherein the gate dielectric layer is in physical contact with sidewall spacers.

13. A method for fabricating an integrated circuit, the method comprising:

providing a dielectric layer overlying a semiconductor substrate, the dielectric layer having a first trench and a second trench;

forming a gate dielectric layer in the first trench and the second trench;

forming a first barrier metal layer overlying the gate dielectric layer;

depositing a second barrier metal layer overlying the first barrier metal layer;

forming a patterned mask such that the patterned mask partially fills the first trench and overlies a first portion of the second barrier metal layer, and wherein a second portion of the second barrier metal layer is exposed;

removing the second portion of the second barrier metal layer;

removing the patterned mask;

forming a work function material layer within the first trench and the second trench;

forming a mask material within the first trench and the second trench;

etching the mask material such that the mask material fills a portion of the first trench and a portion of the second trench;

anisotropically etching a portion of the work function material layer and a portion of the first barrier metal layer;

etching a portion of the gate dielectric layer;

removing the mask material from the first trench and the second trench;

depositing a conductive gate material overlying the work function material layer in the first trench and the second trench; and

removing a portion of the conductive gate material within the first trench and the second trench.

14. The method of claim 13 , wherein etching a portion of the gate dielectric layer comprises etching a portion of the gate dielectric layer using a dry plasma process.

15. The method of claim 13 , wherein anisotropically etching a portion of the work function material layer and a portion of the first barrier metal layer comprises forming a beveled surface of the first barrier metal layer and the work function material layer.

16. The method of claim 13 , wherein forming the gate dielectric layer comprises forming a hafnium oxide layer.

17. The method of claim 13 , wherein forming the first barrier metal layer comprises depositing a titanium nitride layer and depositing a tantalum nitride layer overlying the titanium nitride layer.

18. The method of claim 13 , wherein forming the work function material layer comprises forming a titanium aluminum layer.

19. The method of claim 13 , wherein depositing the second barrier metal layer comprises depositing a titanium nitride layer.