A first dielectric layer is formed overlying the substrate and has {HEAD ~ a dielectric island} surrounded by {TAIL ~ a ring shaped trench} 
surrounded by
A first dielectric layer is formed overlying the substrate and has { HEAD ~ a dielectric island } surrounded by { TAIL ~ a ring shaped trench }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL