According to the present invention, provided is a semiconductor device
including: a p-type silicon substrate; a shallow n-well formed in the
silicon substrate; a shallow p-well formed beside the shallow n-well in
the silicon substrate; and a deep n-well which is formed beside the
shallow p-well in the silicon substrate, and which is deeper than the
shallow p-well. In addition, a deep p-well, which is deeper than the
shallow p-well, is formed between the shallow p-well and the deep n-well
in the silicon substrate.