The invention discloses a
semiconductor structure and a forming method thereof. The forming method comprises the steps of providing a substrate, and forming a to-be-etched layer on the substrate, forming a core layer and a plurality of sacrificial
layers located in the core layer on the to-be-etched layer, and enabling the sacrificial
layers to be arranged at intervals, removing part of the core layer between the adjacent sacrificial
layers to form a first groove penetrating through the core layer, and exposing the sacrificial layers from the side wall of the first groove, carrying out first
ion doping treatment on the core layer of the side wall of the first groove, wherein the first
ion doping treatment is suitable for increasing the
etching resistance of the core layer of the side wall of the first groove, forming a side wall on the side wall of the first groove, after first
ion doping processing and side wall forming are carried out, removing the sacrificial layer, forming a second groove penetrating through the core layer, and isolating the second groove and the first groove by a side wall, and
etching the to-be-etched layers at the bottoms of the first groove and the second groove by taking the core layer and the side walls as masks. According to the embodiment of the invention, the probability that the core layer on the side wall of the first groove is mistakenly etched in the step of removing the sacrificial layer is reduced.