Semiconductor device and method for fabricating the same
A method for fabricating semiconductor device includes the steps of first providing a substrate having a first region and a second region, forming a first bottom barrier metal (BBM) layer on the first region and the second region, forming a first work function metal (WFM) layer on the first BBM layer on the first region and the second region, and then forming a diffusion barrier layer on the first WFM layer.
1. A semiconductor device, comprising:
a substrate having a first region and a second region;
a gate structure on the first region and the second region of the substrate, wherein the gate structure comprises:
a first bottom barrier metal (BBM) layer on the first region and the second region;
a first work function metal (WFM) layer on the first region;
a diffusion barrier layer on the first WFM layer; and
a second WFM layer on a top surface and a sidewall of the diffusion barrier layer.
2. The semiconductor device of claim 1 , further comprising a low resistance metal layer on the second WFM layer.
3. The semiconductor device of claim 1 , wherein the first WFM layer comprises a p-type WFM layer and the second WFM layer comprises a n-type WFM layer.
4. The semiconductor device of claim 1 , wherein the first BBM layer and the diffusion barrier layer comprise a same material.
5. The semiconductor device of claim 1 , further comprising a second BBM layer between the first BBM layer and the substrate.
6. The semiconductor device of claim 5 , wherein the first BBM layer and the second BBM layer comprise different materials.
7. A semiconductor device, comprising:
a substrate having a first region and a second region;
a gate structure on the first region and the second region of the substrate, wherein the gate structure comprises:
a first bottom barrier metal (BBM) layer on the first region and the second region, wherein a thickness of the first BBM layer on the second region is less than a thickness of the first BBM layer on the first region;
a first work function metal (WFM) layer on the first region; and
a diffusion barrier layer contacts a surface of the first WFM layer on the first region and the first BBM layer on the second region.
8. The semiconductor device of claim 7 , further comprising:
a second WFM layer on the diffusion barrier layer; and
a low resistance metal layer on the second WFM layer.
9. The semiconductor device of claim 8 , wherein the first WFM layer comprises a p-type WFM layer and the second WFM layer comprises a n-type WFM layer.
10. The semiconductor device of claim 7 , wherein a thickness of the first BBM layer on the first region is equal to a combined thickness of the first BBM layer and the diffusion barrier layer on the second region.
11. The semiconductor device of claim 7 , wherein the first BBM layer and the diffusion barrier layer comprise a same material.
12. The semiconductor device of claim 7 , further comprising a second BBM layer between the first BBM layer and the substrate.
13. The semiconductor device of claim 12 , wherein the first BBM layer and the second BBM layer comprise different materials.