{HEAD ~ A barrier layer} is formed that extends over the core region and a pre metal dielectric film is formed that extends over {TAIL ~ the barrier layer} 
{ HEAD ~ A barrier layer } is formed that extends over the core region and a pre metal dielectric film is formed that extends over { TAIL ~ the barrier layer }
HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL