a silicon nitride liner on the sidewalls and on {HEAD ~ the top surface} of {TAIL ~ each gate electrode} 
a silicon nitride liner on the sidewalls and on { HEAD ~ the top surface } of { TAIL ~ each gate electrode }
OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL