A semiconductor device includes a substrate, a first barrier layer disposed on the substrate, a first dielectric layer disposed on the first barrier layer, and a second barrier layer disposed on the first barrier layer. The semiconductor device further includes a third barrier layer and a first metal gate each being disposed between a first portion of the second barrier layer and a second portion of the second barrier layer. The first metal gate is disposed between the third barrier layer and the substrate. The semiconductor device further includes a second dielectric layer. The third barrier layer is disposed between the first metal gate and the second dielectric layer. The semiconductor device further includes a second metal gate. The semiconductor device further includes a contact hole positioned between the first metal gate and the second metal gate.