| 摘要 |
PURPOSE:To reduce the breakover current of a pnpn switcing element by surrounding a four-layer switching function region with two-layer rectifying function region, increasing the avalanche breakdown voltage of the central pn-junction in the rectifying region and decreasing the voltage in the switching region. CONSTITUTION:The two-layer rectifying region (diode region) 102 of pn-junction is disposed to surround the four-layer switching function region (thyristor region) 101 of the pnpn-junction of a semiconductor substrate to form a reverse conducting switching element. Then, p-type first base layer 103 and n-type second base layer 104 are formed in stepwise configuration. The impurity distribution gradients a1, a2 of the regions 101, 102 are set to become a1>a2, and the breakdown voltage of the central pn-junction of the region 102 is set higher than the region 101. Thus, the breakover current is decreased to prevent the initial turn-off in the vicinity of the passivation portion 105 and to prevent the variation of the withstand voltage due to the local temperature change so as to improve the reliability of the switching element. |
