Embodiments of the present disclosure provide semiconductor device structures. In one embodiment, the semiconductor device structure includes a gate dielectric layer, a gate electrode layer in contact with the gate dielectric layer, a first self-aligned contact (SAC) layer disposed over the gate electrode layer, an isolation layer disposed between the gate electrode layer and the first SAC layer, and a first sidewall spacer in contact with the gate dielectric layer, the isolation layer, and the first SAC layer.