process 214 a well region 216 of the first conductivity type is formed above the well region 202 and under the well region 208 exposed by the patterned mask layer 212 in one embodiment the well region 216 is a p type region and has a p type dopant concentration of about 10 16 10 17 atoms cm 3 next another ion implant process 218 is then performed on the well region 208 exposed by the patterned mask layer 212 using the patterned mask layer 212 as an implant mask to implant dopants of the second conductivity type into the well region 208 in fig9 after removal of the patterned mask layer 212 a well region 220 of the second conductivity type forms and replaces the well region 208 shown in fig8 in one embodiment the well region 220 is an n type region and has an n type dopant concentration of about 10 16 10 17 atoms cm 3 next a plurality of isolation structures 222 are formed in various portions of the well regions 208 210 and 220 and a plurality of doping regions 224 and 226 are then formed in various portions of the well regions 208 210 and 220 and a gate stack 240 is then formed over a portion of the well region 220 and a portion of the well region 210 adjacent thereto the isolation structures 222 can be for example field oxides fox or shallow trench isolations sti and can be formed by the known isolation fabrication techniques the isolation structures 222 are illustrated as sti structures in fig9 but are not limited thereto the isolation structures 222 are formed in various portions of the well regions 208 210 and 220 and thus define a plurality of regions for forming the.