| 摘要 |
PURPOSE:To obtain a highly reliable device without erroneous operations, by isolating N type island regions by a double P type region wherein an N type region is interposed. CONSTITUTION:The double P<+> isolating layers 301, 302 are formed across the interposed region 303 wherein an N epitaxial layer is left as it is. N<+> layers 304, 305 are provided on the bottom and surface of the N layer 303 and go around the reduction of resistance. To isolate transistors Tr1, Tr2, a P type substrate 101 and P<+> layers 301 and 302 are grounded, and an N layer 303 surrounding a pnp Tr1 is also grounded by a wiring 306. In this constitution, when a negative voltage is impressed on an N type island 103, an npn transistor by the N layer 303, P<+> layer 301 and N island 103 is formed and turned equivalent to a diode of collector base circuit, and the current when forward bias of a junction between the P<+> layer 301 and N island 103 is supplied from a ground potential resulting in no influences to adjacent elements. Therefore, even when an npn Tr2 is at an adjoining location, erroneous operations do not occur. |
