NONVOLATILE SEMICONDUCTOR MEMORY DEVICE AND DEPLETION TYPE MOS TRANSISTOR

摘要

PROBLEM TO BE SOLVED: To provide a nonvolatile semiconductor memory device and a depletion type MOS transistor, which improve a breakdown voltage of a transistor and improve operation reliability.SOLUTION: The transistor is equipped with: a gate electrode 26; a channel region 22 having a first impurity concentration; a source and drain diffusion region 21 having a second impurity concentration higher than the first impurity concentration; an overlapping region 24 which is formed in a region where the channel region 22 overlaps the source and drain diffusion region 21 and has a third impurity concentration higher than the second impurity concentration region; a contact region 23 having a fourth impurity concentration higher than the second impurity concentration; and an impurity diffusion region 27 which is formed inside a part of the source and drain diffusion region 21 and has a fifth impurity concentration higher than the second impurity concentration and lower than the fourth impurity concentration. The impurity diffusion region 27 is in contact with the contact region 23 and away from the overlapping region 24.