| 摘要 |
A semiconductor layer provided on a BOX (buried oxide) layer includes a first P-type region, an N+-type region, and an N−-type region which together form a diode. A plurality of second P-type regions are provided on a bottom part of the semiconductor layer. A plurality of insulating oxide films are interposed between the plurality of second P-type regions. When the diode is in a reverse-biased state, the second P-type region directly below the N+-type region is approximately the same in potential as the N+-type region. The second P-type region will be lower in potential relative to this second P-type region directly below the N+-type region, as the second P-type region gets nearer to the first P-type region. Electric field concentration can thus be relaxed at an interface between the semiconductor layer and the BOX layer, whereby improvement in breakdown voltage of the diode is realized.
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