A method for fabricating a semiconductor device is provided. The method includes: forming an inter-layer insulation layer on a substrate; forming a hard mask layer on the inter-layer insulation layer; etching the hard mask layer using a contact mask; and etching the inter-layer insulation layer using the hard mask layer as an etch barrier, thereby obtaining an opening wherein the etching of the hard mask layer and the etching of the inter-layer insulation layer are performed in one etch chamber.