A dry etching method, with a gas containing nitrogen added to an etching gas containing a halogen compound for an SiC film, applies a low dielectric constant film to an interlayer insulating film and reduces parasitic capacitance between groove wirings. The apparatus for manufacturing compacted irons according to the present invention includes a couple of rollers for compacting reduced materials containing fine reduced irons and manufacturing compacted irons, a guide chute for guiding compacted irons which are discharged from the couple of rollers; and crushers for crushing compacted irons which are guided into the guide chute. A pair of traffic matrices that is characterized by having the least merging cost is then merged.