| 摘要 |
PROBLEM TO BE SOLVED: To reduce electric field concentration in a high breakdown voltage MOS transistor of a offset structure. SOLUTION: A silicon oxide film 19 is formed on the upper surface of an N type diffusion layer 12 (outside of the V shaped diffusion layer 12) between a P type diffusion layer 13 and an N type drain diffusion layer 17 on the N type diffusion layer 12, and the outer periphery of the silicon oxide film has tilted angles not smaller than 3 degrees and not larger than 30 degrees. Consequently, when a voltage BVdss is applied between a drain and a gate, the influence of a gate electrode 15 on the interior of silicon of the N type diffusion layer 12 slowly varies due to a variation in the thickness of the silicon oxide film 19. As a result, electric field concentration at an end of the silicon oxide film 19 is reduced to suppress an increase in electric field intensity, so that a breakdown when the impurity concentration of the N type diffusion layer 12 can be prevented. Thus a breakdown voltage BVdss can be increased while preventing increase of an ON resistance. COPYRIGHT: (C)2009,JPO&INPIT
|
