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