Patent ID: 7989898
Filing Date: 2011-08-02
Classification: H01L

Abstract:
1. A dual workfunction semiconductor device comprising: a first transistor in a first region of a semiconductor substrate, the first transistor comprising a first gate stack having a first effective workfunction, wherein the first gate stack comprises a first gate dielectric capping layer over the semiconductor substrate in the first region, a gate dielectric host layer overlying the first gate dielectric capping layer, a first metal gate electrode layer overlying the gate dielectric host layer, a barrier metal gate electrode overlying the first metal gate electrode layer, a second gate dielectric capping layer overlying the barrier metal gate electrode, and a second metal gate electrode overlying the second gate dielectric capping layer; and a second transistor in a second region of the semiconductor substrate, the second transistor comprising a second gate stack having a second effective workfunction being different from the first effective workfunction, wherein the second gate stack comprises a gate dielectric host layer overlying the semiconductor substrate in the second region, a first metal gate electrode overlying the gate dielectric host layer, a second gate dielectric capping layer overlying the first metal gate electrode, and a second metal gate electrode overlying the second gate dielectric capping layer, wherein the second metal gate electrode layer from the first gate stack and the second metal gate electrode from the second gate stack are formed by the same metal composition as the first metal gate electrode layer from the first gate stack and the first metal gate electrode from the second gate stack.