METHOD OF FORMING A SHALLOW TRENCH ISOLATION STRUCTURE WITH REDUCED LEAKAGE CURRENT IN A SEMICONDUCTOR DEVICE

摘要

A method for fabricating a shallow trench isolation structure (94) for a subthreshold kink-free semiconductor memory device includes the steps of forming an oxide (62) -nitride (64) -oxide (66) -nitride (68) stack on top of a semiconductor substrate (60), etching shallow trenches (72) in selected areas and filling them with an insulating material (74) so that it is level with the top nitride layer (68), removing the top nitride layer, depositing a protective material (82) on top of a first device area (84), removing the top oxide layer {66) in a second device area (86), removing the protective material, removing the bottom nitride layer (64) in the second device area, performing an oxide etch to the whole device to remove the top oxide layer (66) in the first device area (84) and the bottom oxide layer (62) in the second device area (86), removing the bottom nitride layer (64) and the bottom oxide layer (62) in the first device area (84).