Device isolation structure and manufacturing method thereof, and semiconductor device

Abstract

An example manufacturing method includes performing first ion implantation into a first area of a substrate to form a buried layer. Second ion implantation into a second area of the substrate is performed to form a pre-dopant, where the second area is disposed around a periphery of the first area, and a thermal diffusion capability of ions in the pre-dopant is higher than a thermal diffusion capability of ions at the buried layer. An epitaxial layer is formed on a side, of the substrate, on which the buried layer and the pre-dopant are disposed. Third ion implantation into the epitaxial layer is performed, in correspondence to the second area, to form a deep well. Thermal annealing is performed to thermally diffuse ions at the buried layer, in the pre-dopant, and in the deep well.