| 摘要 |
PURPOSE:To protect the pn-junction of an internal circuit in a bipolar integrated circuit against damage and deterioration thereof by forming the surge preventive circuit integral with a semiconductor substrate having the internal circuit and lowering the voltage when the surge voltage is applied thereto. CONSTITUTION:A grounding electrode 28 is coated on the back surface of a p<+>- type silicon substrate 1, and two n<+>-type buried regions 17, 26 are diffused on the surface thereof. Then, an n-type layer 2 is epitaxially grown on the entire surface including these regions, isolated into island state by a plurality of p<+>-type regions 3 reaching the substrate 1, the portion (a) having no buried regions of the isolated layer 2 and the portion (b) having the region 17 are used for the surge preventive circuit, and the region (c) having the region 26 is used for the internal circuit. Thereafter, p-type resistive regions 4, 9 are diffused in the portions (a) and (b), respectively, and a p-type base region 18 and an n<+>-type emitter region 23 disposed therein are formed normally in the portion (c). Then, electrode wiring is executed, and the portion (c) is protected by the portions (a) and (b). |
