a second conductive type high voltage well, which is formed in {HEAD ~ the substrate} beneath {TAIL ~ the upper surface} 
beneath
a second conductive type high voltage well , which is formed in { HEAD ~ the substrate } beneath { TAIL ~ the upper surface }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL