Semiconductor device and method for fabricating the same
A semiconductor device includes a substrate having a first region and a second region and a gate structure on the first region and the second region of the substrate. The gate structure includes 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; and a diffusion barrier layer on a top surface and a sidewall of the first WFM layer on the first region and the first BBM layer on the second region. Preferably, 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.
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, 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 on a top surface and a sidewall of the first WFM layer on the first region and the first BBM layer on the second region.
2. The semiconductor device of claim 1 , further comprising:
a second WFM layer on the diffusion barrier layer; and
a low resistance metal layer on the second WFM layer.
3. The semiconductor device of claim 2 , 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 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.
5. The semiconductor device of claim 1 , wherein the first BBM layer and the diffusion barrier layer comprise a same material.
6. The semiconductor device of claim 1 , further comprising a second BBM layer between the first BBM layer and the substrate.
7. The semiconductor device of claim 6 , wherein the first BBM layer and the second BBM layer comprise different materials.