SEMICONDUCTOR MEMORY DEVICE HAVING A TRIPLE WELL

摘要

a p-substrate (21) which is biased first; a n-well (22) which is fabricated in the p-substrate (21) and is biased second; a first p-well (23) which is fabricated in the n-well (22) and is biased first or third; a second p-well (24) which is fabricated in the n-well (22) and is biased first; a MOS transistor which the first p-well (23) and the second p-well (24) are separated each other and are formed in the n-well (22).