Method of manufacturing semiconductor device having shallow trench isolation (STI)

A method of manufacturing a semiconductor device having a shallow trench isolation includes steps of forming a mask layer on a semiconductor substrate, forming a shallow trench in a semiconductor substrate using the mask layer, forming at least one step in the semiconductor substrate at the top of the shallow trench, and then forming a liner layer over the entire surface of the semiconductor substrate so as to line the shallow trench and thereby offer protection during subsequent oxidation. When the mask layer is subsequently removed, the at least one step in the semiconductor substrate allows portions of the liner layer extending outside the shallow trench to be removed without creating problematic dents in the structure.