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