Patent ID: 8704294

Claim:
A semiconductor device having a metal gate comprising: a substrate having a first gate trench and a second gate trench formed thereon; a gate dielectric layer respectively formed in the first gate trench and the second gate trench; a first work function metal layer formed in the first gate trench; an inter layer formed between the gate dielectric layer and the first work function metal layer, the inter layer directly contacting the first work function metal layer and the gate dielectric layer, respectively; a second work function metal layer respectively formed in the first gate trench and the second gate trench, an upper area of the second work function metal layer in the first gate trench being larger than an upper area of the first work function metal layer in the first gate trench; a filling metal layer formed on the first work function metal layer and the second work function metal layer; wherein the inter layer has a height extending only to a height of the first work function metal in the first gate trench and with an upper edge directly contacting the upper area of the second work function metal in the first gate trench.