According to one embodiment, a method for manufacturing a semiconductor device includes forming a mask layer on a layer to be etched. The mask layer contains at least one type of a metal, boron, and carbon. The metal is selected from a group including tungsten, tantalum, zirconium, hafnium, molybdenum, niobium, ruthenium, osmium, rhenium and iridium. A composition ratio of the metal is higher than a composition ratio of the boron and a composition ratio of the carbon. The method includes making a hole or a slit in the layer to be etched by performing a dry etching to the layer to be etched using the mask layer being patterned.