A dual workfunction semiconductor device and a device made thereof is disclosed. In one aspect, the device includes a first gate stack in a first region and a second gate stack in a second region. The first gate stack has a first effective workfunction, and the second gate stack has a second effective workfunction different from the first effective workfunction. The first gate stack includes a first gate dielectric capping layer, a gate dielectric host layer, a first metal gate electrode layer, a barrier metal gate electrode, a second gate dielectric capping layer, and a second metal gate electrode. The second gate stack includes a gate dielectric host layer, a first metal gate electrode, a second gate dielectric capping layer, and a second metal gate electrode.