Method of manufacturing a semiconductor device

A method for fabricating a semiconductor device, comprising:

• providing a substrate having an active area and a trench isolation region surrounding the active area, wherein the trench isolation region protrudes from a top surface of the active area and forms a step height at an interface between the active area and the trench isolation region;
• performing a first lithographic process to form a first patterned resist layer on the substrate, wherein the first patterned resist layer has a first opening exposing the active area and partially exposing the trench isolation region;
• etching the exposed trench isolation region through the first opening;
• removing the first patterned resist layer;
• depositing a hard mask layer on the substrate, the hard mask layer comprising a first portion on the active area, a second portion on the trench isolation region, and a third portion at the interface between the active area and the trench isolation region, wherein the third portion extends between the first portion and the second portion;
• performing a second lithographic process to form a second patterned resist layer on the hard mask layer, wherein the second patterned resist layer has a second opening exposing the third portion and the first portion of the hard mask layer on the active area, and partially exposing the second portion of the hard mask layer on the trench isolation region;
• and
• performing an isotropic etching process to remove the exposed first portion, the second portion and the third portion of the hard mask layer from the second opening, thereby revealing the active area.