| 摘要 |
PURPOSE:To obtain high withstand voltage of the semiconductor device by forming subjunction surface on the peripheral region of a main junction surface thereof. CONSTITUTION:Annular grooves 51, 52 are formed on a P<+> type layer on an N type substrate, P<+> type layers 41, 42 are formed thereon, and main junction surface 11 and subjunction 12 are separate from each other Both the junction ends 11', 12', 12'' and groove inside surface are coated with protective films 31, 32 respectively. When the junction 11 is reversely biased, a depletion layer 61 is extended to thus reach the subjunction 12, and floating potential is inducted at the layer 42. Accordingly, a depletion layer 62 is newly formed on the N type layer on the periphery of the subjunction 12, a depletion width xd(L) is formed by the synthesis of the layers 61, 62, and surface electric field intensity can be weakened. Accordingly, the surface destructive voltage becomes increased. The withstand voltage thereof can be increased by suitably selecting the distance between the junctions 11 and 12, increasing the subjunctions, and allowing each depletion layer to interfere with each other to increase the width xd(L). |
