METHOD OF FORMING AN ISOLATION STRUCTURE IN A SEMICONDUCTOR DEVICE

摘要

A method for forming an isolation layer in a semiconductor device is provided to protect a lateral side of a trench and to prevent boron segregation and a leakage current by performing a fluorine ion implantation process in the trench. A first ion implant process is performed in a semiconductor substrate(100) to control a threshold voltage. A hard mask layer(116) exposing an isolation region is formed on an upper portion of the semiconductor substrate. The isolation region of the semiconductor substrate is etched to form a trench. A second ion implant process is performed on a sidewall of the trench to implant fluorine ion and to prevent diffusion of impurities implanted for controlling the threshold voltage. An isolation layer is formed on the isolation region to gap-fill the trench. Before the first ion implant process is performed, a TN-well ion implant process and a p-well ion implant process are performed on the semiconductor substrate to form a TN-well junction(102) and a p-well junction(104).