| 摘要 |
PROBLEM TO BE SOLVED: To provide a MOS semiconductor device for reducing a threshold voltage, and for achieving breakdown voltage improvement and on-state resistance reduction. SOLUTION: A semiconductor device includes: an n-type first well diffusion layer 12; an n-type second well diffusion layer 15; a p-type source diffusion layer 13; a p-type third well diffusion layer 19; a p-type drain diffusion layer 14; a gate insulating film 16; a gate electrode 17; a device isolation insulating film 18; and a buffer layer 21. The buffer layer 21 is formed between the first well diffusion layer 12 and the third well diffusion layer 19 to be in contact with an end of the third well diffusion layer 19 opposing the source diffusion layer 13, and extends from immediately below the gate insulating film 16 to a position deeper than a peak of curvature of impurity concentration distribution of the third well diffusion layer 19. The buffer layer has an impurity concentration lower than an impurity concentration in the third well diffusion layer 19. COPYRIGHT: (C)2010,JPO&INPIT
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