A first polishing step is performed to remove {HEAD ~ a portion} of the silicon oxide layer until a thickness of the remaining portion of the oxide layer reaches {TAIL ~ a predetermined thickness} 
A first polishing step is performed to remove { HEAD ~ a portion } of the silicon oxide layer until a thickness of the remaining portion of the oxide layer reaches { TAIL ~ a predetermined thickness }
OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL