Abstract
A semiconductor device includes a barrier layer, a dielectric layer, a first protection layer, a first spacer, and a gate. The dielectric layer is disposed on the barrier layer. The first protection layer is disposed on the barrier layer, in which the first protection layer extends from a first sidewall of the dielectric layer to a top surface of the barrier layer. The first spacer is disposed on and received by the first protection layer, in which a top end of the first protection layer comprises a first curved surface between the first spacer and the dielectric layer. The gate is disposed on the barrier layer, the dielectric layer, and the first spacer. The gate extends from a top surface of the dielectric layer and at least along the first curved surface of the first protection layer to make contact with the top surface of the barrier layer.