| 摘要 |
PROBLEM TO BE SOLVED: To control the high breakdown voltage and large current of a semiconductor switching element by forming a second-conductivity semiconductor layer which is connected with a source electrode between adjacent well layers, and making the total content of impurities in the semiconductor layer smaller than those of impurities in the well layers. SOLUTION: In a parallel-plate single-crystal silicon carbide semiconductor substrate 1 having main surfaces on its top and bottom sides, a low-resistance n+-type drain layer 2 and an n--type drift layer 3 having higher resistance than the layer 2 has are laminated upon another. A plurality of high- concentration p+-type well layers 41 is provided in the drift layer 3 from one main surface of the substrate 1 and a high-concentration n+-type source layer 5 and a p--type layer 10 containing impurities at a total content which is lower than that of impurities in the p+-type well layer 41 are formed in each p+-type well layer 41. The p--type layer 10 is brought into contact with the p-type well layers 41 on both sides. Consequently, the switching of a switching element provided with a voltage clamping function under a high-breakdown voltage and large-current condition can be inhibited.
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