To provide the manufacture of a semiconductor device which forms an insulating film having a flat top excellent in insulation property at a low cost and in a short time.

A undoped silicate glass(USG) film 26 is made to cover aluminum wiring 24 arranged on a field oxide film 22, and an organic SOG(spin-on- glass) layer 28 which is apt to be thick is made in the recess on the surface of the USG layer 26. Consequently, irregularities of the surface of the USG layer 26 can be relaxed to some degree. In addition to this, the flat interwiring insulating film 32, whose top is flat can be obtained by forming a USG layer 30, using vapor growth method utilizing high-density plasma superior in embedding property. Moreover, since the SOG process is made only in the formation process of the organic SOG layer 28, this manufacture can reduce the manufacture cost. Furthermore, with the USG layer 26 and the USG layer 30 of good film quality, the organic SOG layer 28 can be surrounded, so that even if the material quality of the organic SOG layer 28 is not so good, an interwiring insulating film 32 superior in insulation property can be obtained.