c) removing said one or more extractable materials leaving {HEAD ~ a porous structure} comprising said {TAIL ~ one or more non extractable insulation materials} to form said low dielectric constant insulation layer; and 
comprising
c ) removing said one or more extractable materials leaving { HEAD ~ a porous structure } comprising said { TAIL ~ one or more non extractable insulation materials } to form said low dielectric constant insulation layer ; and
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH