Method for fabricating a semiconductor device

A method for fabricating a semiconductor device, the method comprising:

• forming an etch target layer over a substrate, wherein the substrate includes a cell region and a peripheral region;
• forming a first hard mask layer, a second hard mask layer, and an anti-reflective coating layer over the etch target layer;
• forming a photosensitive pattern over the anti-reflective coating layer;
• etching the anti-reflective coating layer to have a width smaller than a width of the photosensitive pattern;
• etching the second hard mask layer;
• performing a main etching treatment and an over-etching treatment on the first hard mask layer to form first hard mask patterns in the cell region, wherein the first hard mask patterns have a sloped profile;
• and
• etching the etch target layer using the first hard mask patterns as an etch mask.