using a wet etch process for etching {HEAD ~ Cu}, etching {TAIL ~ said second layer} 
etching
using a wet etch process for etching { HEAD ~ Cu } , etching { TAIL ~ said second layer }
OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL