Trench isolation structure and method for forming

摘要

An isolation structure is disclosed which isolates an active region (24) from other proximate active regions. The isolation structure utilizes the combination of a LOCOS structure (26) comprising bird's beak structure (26a) and (26b). A trench (34) is formed through the LOCOS structure (26). A channel stop implant region (40) is formed along the sidewalls of the trench (34). A trench plug (46) is used to fill the trench. The isolation structure thereby uses the isolation capabilities of trench isolation structures, but prevents the leakage currents common along trench sidewalls by isolating the trench sidewalls from the active region using the LOCOS structures.