TRENCH STRUCTURE SEMICONDUCTOR DEVICE

摘要

A semiconductor substrate (1) of an IGBT has inner trenches (2a) and outer trenches (2b). An emitter area (3) is formed adjacent to each trench (2a, 2b). A P-type base area (4) is formed adjacent to the emitter area (3) and each trench (2a, 2b). A first N-type base area (31) is formed adjacent to the inner trench (2a). A second N-type base area (32) having a lower impurity concentration than that of the first N-type base area (31) is formed adjacent to the outer trench (2b) and the first N-type base area (31). When an excessive voltage is applied, a breakdown occurs in the vicinity of the inner trench (2a) so that the concentration of an electric current is released to prevent the breakage of the IGBT.