| 摘要 |
PURPOSE:To obtain large capacitance in a small occupying area by forming an impurity layer into a substrate in the lower section of a transistor region, using the impurity layer as a capacitance region and increasing a capacitance area. CONSTITUTION:N-type source-drain 13 are shaped to a p-type Si substrate 11, one part of an n layer is extended to an approximately L shape into the substrate, and the n layer 19 is formed extending over a wide area. A capacitance region is shaped by a depletion layer formed between the n layer 19 and the p-type substrate 11. Consequently, large capacitance is acquired in a small occupying area. The structure can be realized in such a manner that the n layer 19 is shaped to the surface of the p-type Si substrate 11, a p layer is formed in an epitaxial manner and the surface and the n layer 19 are coupled through ion implantation. |
