Fabrication method for a shallow trench isolation structure

摘要

A fabrication method for shallow trench isolation is provided. The method includes forming a pad oxide layer on a substrate, followed by forming a mask layer on the pad oxide layer. The mask layer is then patterned. Using the patterned mask as a mask, the pad oxide layer and the substrate are etched to form a trench in the substrate. A tilt-angled fluorine implantation is performed to form a substrate surface with fluorine ions around the top corner of the trench. A thermal oxidation process is further conducted on a surface of the trench to form a thicker liner oxide layer at the top corner of the trench. An insulation layer is then formed on the substrate, filling the trench. The insulation layer above the mask layer is removed followed by removing the mask layer and the pad oxide layer.