The present invention relates to the technical field of semiconductor manufacturing, and in particular, to a method for forming a semiconductor structure and a semiconductor structure. The method for forming a semiconductor structure comprises: forming an interconnect layer and a conductive layer covered on a surface of the interconnect layer; forming a protective layer covering a surface of the conductive layer away from the interconnect layer; forming a trench penetrating the protective layer and the conductive layer; and filling a dielectric layer in the trench, and forming an air gap in the dielectric layer, the air gap extending from the trench in the conductive layer into the trench in the protective layer.