The zener diode is composed of {TAIL ~ a p type doped region} and {HEAD ~ an n type doped region}, wherein one of the doped regions, formed by deep diffusing impurities from a doped polysilicon layer, is arranged between two adjacent well regions 
The zener diode is composed of { TAIL ~ a p type doped region } and { HEAD ~ an n type doped region } , wherein one of the doped regions , formed by deep diffusing impurities from a doped polysilicon layer , is arranged between two adjacent well regions
OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD 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 OTH OTH OTH OTH OTH OTH OTH