A method for manufacturing a semiconductor device is provided. The method includes the following steps: forming a lining layer on a substrate and a plurality of gate structures; forming a first spacer layer on the lining layer; forming a stop layer on the first spacer layer; forming a first sacrificial layer on the stop layer and between the gate structures; removing a portion of the first sacrificial layer so that the top surface of the first sacrificial layer is located between the upper portions of the gate structures; forming a second spacer layer on the first sacrificial layer and the gate structures; and removing a portion of the second spacer layer so that the remaining second spacer layer is located between the upper portions of the gate structures.