The invention provides a method for manufacturing a semiconductor device. The method comprises the following steps: providing a semiconductor substrate, wherein the semiconductor substrate comprises an NMOS (N-channel Metal-Oxide-Semiconductor Transistor) region and a PMOS (P-channel Metal-Oxide-Semiconductor Transistor) region; sequentially forming an oxide layer and a polycrystalline silicon layer on the semiconductor substrate; removing the polycrystalline silicon layer on the PMOS region; forming a non-crystal germanium telluride layer on the semiconductor substrate; forming a pseudo gate structure of the PMOS region; forming a pseudo gate structure of the NMOS region; forming side wall structures on two sides of the pseudo gate structures; forming a stress material layer on the semiconductor substrate so as to cover the pseudo gate structures, and performing an annealing process; removing the stress material layer; removing the pseudo gate structures; forming gate trenches between the side wall structures. According to the method, a stress memory technique does not need to be respectively performed to the NMOS region and the PMOS region, so that procedures for forming a mask and removing the mask are canceled, the production time is shortened, and the manufacturing cost is lowered.