Semiconductor structure and forming method thereof

The invention provides a method for forming a semiconductor structure, which comprises the following steps of: sequentially forming a liner oxide layer and a first hard mask layer on the middle area of the surface of a semiconductor substrate from bottom to top, simultaneously exposing the surface corresponding to the edge area of the semiconductor substrate, and then forming a second hard mask layer on the edge area of the semiconductor substrate by utilizing a local oxidation process. Forming an edge protection object layer (namely silicon dioxide) on the exposed edge region of the semiconductor substrate, and then carrying out subsequent groove etching, cleaning and other processes on the semiconductor substrate with the edge protection object layer with the silicon dioxide on the edge region. A silicon material in an edge region (crystal edge) of a semiconductor substrate is firstly converted into silicon oxide which cannot be etched in a subsequent groove etching process, and then the silicon oxide is et