| 摘要 |
PURPOSE:To improve IIL element performance characteristics by a method wherein a high-concentration epitaxial layer is formed just under the base of a vertical type NPN transistor and a low-concentration epitaxial layer is formed on said high-concentration epitaxial layer. CONSTITUTION:An N<+> type low-resistance buried layer 2 is formed on a P type silicon substrate 1. On the substrate 1, a high-concentration N type epitaxial layer 3-1 is formed, to be followed by the formation of a low-concentration epitaxial layer 3-2 whose impurity concentration is lower than that of the epitaxial layer 3-1. A P<+> type isolating layer 4 is formed by diffusion to be deep enough to reach the substrate 1, which results in the formation of N type islands 5-1, 5-2. On the island 5-1, an injector 7-1 is formed of a P type IIL element, and then a base 7-2 of a vertical NPN transistor. On the island 5-2, a P type diffused layer 8 is formed with its diffusion shallower than the injection 7-1. An IIL element manufactured by this method is superior in performance characteristics to one manufactured by the conventional method. |
