The invention relates to a semiconductor device, a manufacturing method therefor, and an electronic device. The method comprises the steps: S1, providing a semiconductor substrate, wherein the semiconductor substrate comprises a core region and an input/output region, and the core region and the input/output region are respectively provided with a plurality of fins; S2, forming a grid oxide layer surrounding the fins on the fins in the input/output region; S3, forming virtual oxide layers on the fins of the core region and the grid oxide layer of the input/output region; S4, forming virtual grid electrodes on the fins, and forming interlayer dielectric layers between the virtual grid electrodes; S5, removing the virtual grid electrodes; S6, removing the virtual grid oxide layers; S7, processing the surface of a virtual opening through oxygen plasma. The method solves a problem of pollutant residuals, and further improves the performance and yield of the semiconductor device.