Formation method of semiconductor structure

The invention provides a formation method of a semiconductor structure. The formation method comprises the steps of forming a base, wherein the base comprises a substrate, fin parts and mask layers, wherein the fin parts are arranged on the substrate, and the mask layers are arranged on the fin parts; forming an isolation material layer on the substrate between the fin parts; and forming at least one oxide layer in the fin parts by oxidization step for at least one time, wherein the oxidization step comprises the steps of removing a partial thickness of the isolation material layer so that a part of a side wall of each fin part is exposed out of the isolation material layer; forming a shielding layer on the isolation material layer where the side wall of the fin part is exposed; removing a partial thickness of the isolation material layer below the shielding layer to expose a part of the side wall of the fin part; forming the oxide layer in the fin parts exposed out of the isolation material layer and the shielding layer by oxidization processing; and removing the mask layers and the shielding layer which is used in the oxidization step, wherein the isolation between the fin parts and the substrate can be achieved by the oxidization layer, and the oxidization layer can be used for reducing leakage currents of transistors after the transistors are formed in the fin parts.