| 摘要 |
PURPOSE:To facilitate the selective use of an optional element by a method wherein a selective region, which can be negated by the diffusing dopants of the prescribed conductivity type, is provided between elements. CONSTITUTION:A P-type diffusion layer 6, a P<+> type isolation diffusion film 5 for element isolation, an oxide film 4 and an element isolation oxide film 3 and the like are laminated on a P-type Si substrate 1 and an N-well 2, and when the film 6 is formed into a selective region which can be negated by the diffusion of a conductivity type opposite to that of dopants in an ROM determination process, the optional element such as a transistor and the like can be easily selected and used by merely changing an ROM content determination mask. Besides, results the same as the above can be obtained even when a selective region, which can be brought into a conductive state by the diffusion of dopants, is provided. |
