polishing the insulating layer until {HEAD ~ a top surface} of {TAIL ~ the lower polysilicon gate level} is exposed; and then 
of
polishing the insulating layer until { HEAD ~ a top surface } of { TAIL ~ the lower polysilicon gate level } is exposed ; and then
OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH