{HEAD ~ A wet etching process} is performed to remove {TAIL ~ the first un etched portion} of the substrate after the mask removing process, thereby forming the piezoelectric resonator element 
is performed to remove
{ HEAD ~ A wet etching process } is performed to remove { TAIL ~ the first un etched portion } of the substrate after the mask removing process , thereby forming the piezoelectric resonator element
HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH