| 摘要 |
PURPOSE:To stabilize dielectric strength of a semiconductor device, by forming deep P<+> regions reaching an N<+> buried layer so that the P<+> regions provide a part of the base region of an NPN transistor to be formed in an island region of an epitaxial layer on a P-type substrate having the N<+> buried layer, or provide emitter and collector regions of a lateral PNP transistor. CONSTITUTION:An N<+> buried layer 2 and a P<+> buried layer are formed in a P-type silicon substrate 1 and an N<-> epitaxial layer 3 is deposited thereon. In the wafer thus constructed, a P<+> isolation region 4 is formed by diffusion so deep as to reach the P<+> buried layer. Simultaneously therewith, a P<+> region 6 is formed by diffusion in an island region 5 for an NPN transistor while P<+> regions 8 and 9 are formed in an island region 7 for a lateral PNP transistor such that they all reach the N<+> buried layer 2. A P-type region 10 is then formed by diffusion such that it is joined with the P<+> region 6. Then an N<+> region 11 for a collector electrode is formed by diffusion in the island region 5 and an N<+> region 12 for an emitter region is formed in the P region 10. Simultaneously therewith, N<+> region 13 for a base electrode is formed by diffusion in the island region 7. Accordingly, the semiconductor device is allowed to have increased and stable dielectric strength without increasing sizes of elements.
|
