Method of forming isolation layer of semiconductor device

Abstract

A method of forming an isolation structure of a semiconductor device includes implanting dopants of a first type into a semiconductor substrate to form a doped region in the substrate. A mask layer is provided over the substrate and the doped region of the substrate. The mask layer is patterned to expose an isolation region of the substrate, the isolation region defining an active region, the isolation region and the active region being defined at least partly within the doped region. Dopants of a second type are implanted at an edge of the active region as defined by the isolation region. The isolation region of the semiconductor substrate is etched to form an isolation trench having a depth that extends below a depth of the doped region. Dopants of a third type are implanted on sidewalls of the trench in order to minimize the dopants of the second type provided on the sidewalls of the isolation trench from migrating away from the sidewalls. The trenches are filled with a dielectric layer to form an isolation structure.