The term etching factor refers to the ratio of etching depth with {TAIL ~ respect} to {HEAD ~ the amount} of side etching 
The term etching factor refers to the ratio of etching depth with { TAIL ~ respect } to { HEAD ~ the amount } of side etching
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH