A cleaning method of a semiconductor manufacturing process is provided. The cleaning method is applied to a semiconductor component including a plurality of material layers formed thereon. An opening is defined in the material layers, and a side wall is exposed from the opening. The side wall at least includes a first material layer and a second material layer. At first, a first cleaning process is performed till a lateral etched thickness of the first material layer is equal to a lateral etched thickness of the second material layer. Then, a byproduct formed in the first cleaning process is removed.