The present disclosure provides a semiconductor device and a manufacturing method thereof. The semiconductor device includes a semiconductor layer, a source and a drain located on one side of the semiconductor layer, a blocking layer located on one side of the semiconductor layer, the blocking layer including silicide, wherein the distance between an interface at one side of the blocking layer close to the semiconductor layer and the semiconductor layer is equal to or more than 10 nm, and a gate located between the source and the drain, the gate penetrating through the blocking layer, the gate including a first conductive layer and a second conductive layer, the first conductive layer being close to the semiconductor layer, the second conductive layer being located on one side of the first conductive layer away from the semiconductor layer, and the first conductive layer including nickel.