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