Method for forming semiconductor structure and semiconductor structure

A method for forming a semiconductor structure, comprising:

• providing a substrate, and forming a dielectric layer on a surface of the substrate;
• forming a mask layer on a surface of the dielectric layer, wherein the mask layer is arranged with a first opening penetrating the mask layer in a thickness direction of the mask layer;
• forming a first barrier layer on a sidewall of the first opening, wherein the first barrier layer surrounds and forms a second opening;
• forming a second barrier layer filling the second opening;
• removing the first barrier layer and the second barrier layer by a first etching process until the first barrier layer or the second barrier layer is completely removed, wherein a removed rate of the first barrier layer by the first etching process is different from a removed rate of the second barrier layer by the first etching process;
• and
• removing the dielectric layer exposed by the first opening and part of the substrate exposed by the first opening, to form a bit-line contact opening, wherein a bottom of the bit-line contact opening is arranged with a convex region and a concave region, and the convex region and the concave region have a height difference.