Preparation method of semiconductor structure and semiconductor structure

The invention relates to a preparation method of a semiconductor structure and the semiconductor structure. The preparation method of the semiconductor structure comprises the steps of providing an initial semiconductor structure, wherein the initial semiconductor structure comprises a substrate, a gate structure, a first oxide layer and a dielectric layer; wherein the gate structure is located on the substrate; the first oxide layer is located on the side wall of the gate structure and on the substrate at the edge of the gate structure; the dielectric layer covers the surface of the first oxide layer; growing a second oxide layer on the exposed surface of the substrate and the top of the gate structure; forming a third oxide layer on the surface of the dielectric layer and the surface of the initial second oxide layer; and at least etching the third oxide layer to form a side wall structure which comprises a second oxide layer, a first oxide layer, a dielectric layer and a third oxide layer which are located