sg to achieve the said improvement taking a p type substrate as an example the non volatile memory cell 40 may further comprise a first diffusion region 421 and a second diffusion region 422 formed over a first conductivity region of a first conductivity type such as an n well nw third fourth fifth and sixth diffusion regions 461 462 463 464 may be formed in a second conductivity region of a second conductivity type such as a p well pw seventh and eighth diffusion regions 481 482 may be formed in a third conductivity region of the first type such as another n well nw the p well pw may be located between the two n wells nw the first conductivity region is the first conductivity type and the second conductivity region may be located between the first conductivity region and the third conductivity region in another embodiment the first conductivity region is the second conductivity type and the third conductivity region is located between the first conductivity region and the second conductivity region the floating gate fg 400 may comprise a first gate part 401 formed between the first and second diffusion regions 421 422 and a second gate part 402 formed between the fourth and fifth.