The present invention provides a method for forming a semiconductor structure, including: first, a substrate is provided. Next, at least two gate structures are formed on the substrate, each gate structure including two spacers disposed on two sides of the gate structure. Afterwards, a dry etching process is performed to remove parts of the substrate, so as to form a recess in the substrate, and a wet etching process is performed, to etch partial sidewalls of the recess, so as to form at least two tips on two sides of the recess respectively. In addition, parts of the spacer are also removed through the wet etching process, and each spacer includes a rounding corner disposed on a bottom surface of the spacer.