A manufacturing method of a semiconductor device includes following steps. First gate structures and second gate structures are formed on a first region and a second region of a semiconductor substrate respectively. A spacing distance between the second gate structures is larger than that between the first gate structures. A first ion implantation is preformed to form a first doped region between the first gate structures. A second ion implantation is performed to form a second doped region between the second gate structures. A tilt angle of the second ion implantation is larger than that of the first ion implantation. An implantation dose of the second ion implantation is lower than that of the first ion implantation. An etching process is performed to at least partially remove the first doped region to form a first recess and at least partially remove the second doped region to form a second recess.