Patent ID: 8952451
Filing Date: 2015-02-10
Classification: H01L

Abstract:
1. A semiconductor device having a metal gate comprising: a substrate having a first gate trench and a second gate trench formed thereon, wherein an opening width of the second gate trench is larger than an opening width of the first gate trench; a gate dielectric layer respectively formed in the first gate trench and the second gate trench; a first work function metal layer formed on the gate dielectric layer in the first gate trench and the second gate trench; 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 wider than a lower area of the second work function metal layer in the first gate trench, wherein the second work function metal layer in the first gate trench covers topmost portions of the first work function metal layer in the first gate trench, and topmost portions of the second work function metal layer in the second gate trench are coplanar with topmost portions of the first work function metal layer in the second gate trench; and a filling metal layer formed on the second work function metal layer.