| 摘要 |
PURPOSE:To enable to obtain highly integrated circuit as well as to make them suitable for a D/A converter and the like by a method wherein a two-conductor type buried impurity layer, to be used for a passive element or a wiring, is buried at the lower part of the one-conductive type substrate constituting an active element on the main surface. CONSTITUTION:For example, a p<+> type buried layer 2 is formed on an n type substrate 1a, an n type layer 1b is epitaxially grown and after the buried layer 2 has been connected using p<++> layers 3a and 3b, an MOSFET, for example, is formed on the surface of the epitaxial layer 1b. The substrate 1a is connected to a positive power source and the buried layer 2 is utilized as a resistor by biassing it negatively. A wiring layer is formed by turning the buried layer 2 to p<++> type. Also, when the buried p<++> layer 2 is connected with the diffusion layer 3a only, their junction capacity can be utilized as a capacitor. Thus, the passive element and the wiring layer requiring a large area can be formed in the inner part of the substrate 1 and this enables to form a high density D/A converter and the like which will be used in combination with a plurality of resistance elements, for example. |
