SEMICONDUCTOR DEVICE

摘要

Between a source electrode (25) of a main device (24) and a current sensing electrode (22) of a current detection device (21), a resistor for detecting current is connected. Dielectric withstand voltage of gate insulator (36) is larger than a product of the resistor and maximal current flowing through the current detection device (21) with reverse bias. A diffusion length of a p-body region (32) of the main device (24) is shorter than that of a p-body (31) of the current detection device (21). A curvature radius at an end portion of the p-body region (32) of the main device (24) is smaller than that of the p-body (31) of the current detection device (21). As a result, at the inverse bias, electric field at the end portion of the p-body region (32) of the main device (24) becomes stronger than that of the p-body region (31) of the current detection device (21). Consequently, avalanche breakdown tends to occur earlier in the main device 24 than the current detection device (21).

主权项

1. A semiconductor device comprising:
a main device; an insulated gate semiconductor device for current detection and configured to be smaller in size than the main device; and a resistor connected to the main device and the insulated gate semiconductor device, wherein under reverse bias, withstand voltage of the insulated gate semiconductor device is higher than withstand voltage of the main device, wherein the main device comprises:
a first semiconductor region of a second conductivity type selectively formed in a surface layer of a first principal surface of a first semiconductor layer of a first conductivity,a first high-density semiconductor region of the first conductivity selectively formed in a surface layer of the first semiconductor region of the second conductivity type,a first gate electrode formed on a first gate insulator film, over a surface of the first semiconductor region of the second conductivity type between the first high-density semiconductor region of the first conductivity and the first semiconductor layer of the first conductivity,a first electrode contacting the first high-density semiconductor region of the first conductivity and the first semiconductor region of the second conductivity type, anda second electrode formed at a side nearer to a second principal surface of the first semiconductor layer of the first conductivity, and the insulated gate semiconductor device for current detection comprises:
a second semiconductor region of the second conductivity type selectively formed in a surface layer of a first principal surface of a second semiconductor layer of the first conductivity,a second high-density semiconductor region of the first conductivity selectively formed in a surface layer of the second semiconductor region of the second conductivity type,a second gate electrode formed on a second gate insulator film over a surface of the second semiconductor region of the second conductivity type between the second high-density semiconductor region of the first conductivity and the second semiconductor layer of the first conductivity,a third electrode contacting the second high-density semiconductor region of the first conductivity and the second semiconductor region of the second conductivity type, anda fourth electrode formed at a side nearer to a second principal surface of the second semiconductor layer of the first conductivity, whereinthe resistor is connected to the first electrode and the third electrode,the second electrode and fourth electrode are short-circuited, anddiffusion depth of the first semiconductor region of the second conductivity type is shallower than diffusion depth of the second semiconductor region of the second conductivity type.