Patent ID: 8551876

Claim:
A manufacturing method for a semiconductor device having a metal gate comprising: providing a substrate having at least a first semiconductor device and a second semiconductor device formed thereon, the first semiconductor device being a p-type semiconductor device and the second semiconductor device being an n-type semiconductor device; forming a first gate trench in the first semiconductor device and a second gate trench in the second semiconductor device; forming a first work function metal layer in the first gate trench and the second trench after forming the first gate trench and the second trench; performing a decoupled plasma oxidation (DPO) to the first work function metal layer; removing the first work function metal layer from the second trench after the DPO; forming a second work function metal layer in the second gate trench after the DPO; and performing a decoupled plasma nitridation (DPN) to the second work function metal layer.