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