Formation method of semiconductor structure

A forming method of a semiconductor structure comprises the steps that a to-be-etched layer is provided, and the to-be-etched layer comprises a first region and a second region; forming a plurality of first core layers which are separated along a first direction parallel to the surface of the substrate on the first region; forming a plurality of second core layers which are separated along a second direction parallel to the surface of the substrate on the second region, wherein the second size of the adjacent second core layers is greater than the first size of the adjacent first core layers; forming side wall material layers on the side wall surfaces and the top surfaces of the first core layer and the second core layer; the side wall material layer is etched through a first etching process, a first side wall is formed on the side wall of the first core layer, and the first side wall has a first size in the first direction; the side wall material layer is etched through a second etching process, a second sid