The porous insulation layer is formed by {HEAD ~ a chemical vapor deposition} of {TAIL ~ a mixture} of the insulation material and a second extractable material; and then subsequently selectively removing the second extractable material, thereby leaving behind a porous matrix of the insulation material, comprising the low dielectric constant insulation layer 
of
The porous insulation layer is formed by { HEAD ~ a chemical vapor deposition } of { TAIL ~ a mixture } of the insulation material and a second extractable material ; and then subsequently selectively removing the second extractable material , thereby leaving behind a porous matrix of the insulation material , comprising the low dielectric constant insulation layer
OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH