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