A method for fabricating a semiconductor structure includes: providing a substrate and a dielectric layer on the substrate; and forming an etching mask on the dielectric layer; and etching the dielectric layer using the etching mask to form at least one opening therein. The etching mask includes: a hard mask layer, a photoresist layer, and a hexamethyldisilazane (HMDS) layer. The photoresist layer is located over the hard mask layer, and the HMDS layer is located between the hard mask layer and the photoresist layer.