Method for forming semiconductor structure, and semiconductor structure

A method for forming a semiconductor structure, comprising:

• providing a substrate, wherein a gate structure is formed on the substrate;
• forming first side walls covering side surfaces of the gate structure, wherein the first side walls have a first preset thickness in a direction parallel to a plane of the substrate;
• performing first ion implantation on the substrate on both sides of the gate structure exposed to the first side walls;
• removing a part of the first side walls to form second side walls, wherein the second side walls have a second preset thickness in the direction parallel to the plane of the substrate;
• performing second ion implantation on the substrate on both sides of the gate structure, wherein a doping type of the first ion implantation and a doping type of the second ion implantation are different;
• wherein the first ion implantation is LDD ion implantation;
• and the second ion implantation is Halo ion implantation;
• and
• after performing the second ion implantation, performing thermal diffusion on the substrate on both sides of the gate structure to form LDD areas and Halo areas in the substrate,
• wherein in a direction perpendicular to the plane of the substrate, projections of the LDD areas and a projection of the gate structure do not overlap.