A well 31 having {TAIL ~ a first diffusion type} is formed in {HEAD ~ a substrate} 30 
A well 31 having { TAIL ~ a first diffusion type } is formed in { HEAD ~ a substrate } 30
OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH