The invention provides a manufacturing method of a semiconductor device, and relates to the technical field of semiconductors. The method comprises the steps that a semiconductor substrate is provided, and multiple spaced nucleuses are formed on the semiconductor substrate; a space wall material layer is formed so as to cover the nucleuses and the nucleuses substrate, and the space wall material layer between the adjacent nucleuses is enabled to form an opening in an enclosing way; a sacrificial material layer is formed so as to fill in the openings; first plasma injection is performed so as to modify the space wall material layer arranged on the top surface of the nucleuses and form a first modified space wall material layer; the sacrificial material layer and the first modified space wall material layer are removed; the part arranged on the bottom part of the openings of the space wall material layer is removed so as to form the space wall on the side wall of the nucleuses; and the nucleuses are removed. According to the manufacturing method, the process window can be enlarged and the odd-even performance can be improved.