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