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