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 method for fabricating semiconductor device, comprising:
providing a substrate having a first region and a second region, wherein the first region comprises a PMOS region and the second region comprises a NMOS 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;
forming a diffusion barrier layer on the first WFM layer; and
removing the diffusion barrier layer on the second region.
2. The method of claim 1 , further comprising:
forming a gate structure on the substrate on the first region and the second region;
forming an inter-layer dielectric (ILD) layer around the gate structure;
removing the gate structure to form a recess;
forming the first BBM layer in the recess;
forming the first WFM layer on the first BBM layer;
forming the diffusion barrier layer on the first WFM layer;
removing the diffusion barrier layer and the first WFM layer on the second region;
forming a second WFM layer on the diffusion barrier layer on the first region and the first BBM layer on the second region; and
forming a low resistance metal layer on the second WFM layer to form a metal gate.
3. The method of claim 2 , further comprising forming the second WFM layer on a top surface and a sidewall of the diffusion barrier layer.
4. The method 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.
5. The method of claim 1 , wherein the first BBM layer and the diffusion barrier layer comprise a same material.
6. The method of claim 1 , further comprising forming a second BBM layer on the substrate before forming the first BBM layer.
7. The method of claim 6 , wherein the first BBM layer and the second BBM layer comprise different materials.