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