planarizing the second layer of dielectric material, using {HEAD ~ the plurality} of {TAIL ~ carbon nanotubes} as a stopping layer 
planarizing the second layer of dielectric material , using { HEAD ~ the plurality } of { TAIL ~ carbon nanotubes } as a stopping layer
OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH