| 摘要 |
PROBLEM TO BE SOLVED: To perform turn off at a high speed and to improve the breakdown strength of a semiconductor device which controls the channels forming current paths with the potential applied to the gate electrodes. SOLUTION: An electrostatic induction thyristor controls conduction and interruption of current by opening and closing channels constituting current paths between n-type cathode areas 12 formed on one surface of an n-type silicon substrate and a p-type anode area 15 formed on the other surface with the potential applied to the gate areas 14 and guard areas 18-20, by forming the guard areas of a p+-type guard areas 18 and 19 and a p-type auxiliary guard area 20 containing a low density of impurities formed between them. Diffusion of electrons toward the underside of the guard areas is suppressed and electrons are speedily ejected at the time of interruption. Since the ejection of electrons is performed uniformly, there is few concentration of electric field and the breakdown strength becomes high.
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