| 摘要 |
PURPOSE: To prevent the reduction in the breakdown strength at a low temperature, which is caused by the application of a field plate structure, and to obtain stable breakdown strength characteristics by a breakdown strength structure of a small size by a method wherein an RESURF structure and a guard ring structure are used in combination in the device. CONSTITUTION: A p-type lightly doped diffused layer (a p-type layer) 3 is formed in an n-type silicon substrate 1 using a field oxide film 5 or the like as a mask, but the surface impurity concentration of the layer 3 is set in a concentration of about 1×10<16> /cm<3> or lower for spreading effectively a depletion layer in this p-type layer 3. A plurality of guard rings 4 and a stopper region 9 are formed of a p-type diffused layer, which can be formed simultaneously with a p-type anode region 2 of an active region 11, and a field plate, which is formed using Al electrodes 71 and reaches up to the vicinities of the adjacent guard rings 4, is provided on the oxide film 5. Accordingly, the reduction in the breakdown strength of a high-breakdown strength semiconductor device at a low temperature, which is caused by a field plate structure which is continuously provided up to the peripheral edge part of a semiconductor base body, is eliminated and the increase in the area of the device because of a guard ring structure can be inhibited by a combination of an RESURF structure with the guard ring structure.
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