A semiconductor manufacturing method includes: forming a seed film including a first metal over a bottom surface and a side wall of an opening portion formed over interlayer insulating films and a field portion located over the interlayer insulating film except the opening portion, forming a resist over the seed film and filling the opening portion with the resist, removing part of the resist, exposing the seed film formed over the upper portion of the side walls of the opening portion and the field portion, forming a cover film including a second metal, whose resistivity is higher than that of the first metal, over the seed film located over the upper portion of the side wall of the opening portion and the field portion, exposing the seed film by removing the resist, and forming a plating film including the first metal over the exposed seed film.