Fabrication of shallow trench isolation structures with rounded corner and self-aligned gate

摘要

For fabricating a shallow trench isolation structure, a notched masking structure is formed over an active area of a semiconductor substrate. A shallow trench opening is formed at a side of the active area with a top corner of the shallow trench opening being exposed and facing a notched surface of the notched masking structure. Liner oxide is formed in a thermal oxidation process at the top corner of the shallow trench opening to round the top corner of the shallow trench opening. The liner oxide may also be formed on walls including the bottom corner of the shallow trench opening during the thermal oxidation process. The shallow trench opening is then filled with a trench dielectric material to form the shallow trench isolation structure.