{HEAD ~ The semiconductor} filled {TAIL ~ portion} of each trench then serves as a drain and source of a field effect transistor 
filled
{ HEAD ~ The semiconductor } filled { TAIL ~ portion } of each trench then serves as a drain and source of a field effect transistor
HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH