| 摘要 |
PURPOSE:To improve integration degree, by holding a semiconductor layer, which has the first conductive type immediately beneath a memory insulating film by semiconductors, which are mutually connected and have the second conductive type, providing a triple structure in this way, thereby increasing the capacity of a bulk depletion layer in a memory part. CONSTITUTION:An epitaxial P layer 3 is formed on a P<-> layer 2. On a substrate at a region surrounded by an element separating insulating film 4 formed on the P<-> layer 2, a polysilicon layer 6, which constitutes the gate of an MOS transistor, is formed through an insulating film 5. On the substrate between the polysilicon layer 6 and the element separating insulating film 4, a polysilicon layer 8 is formed through an insulating film 7 as a memory insulating film. Under the insulating film 7, a triple structure, which comprises an N<+> layer 10 directly below the film 7, a P<+> layer 11 beneath the layer 10, and an N<+> layer 12 beneath the layer 11, is provided. The upper N<+> layer 10 and the lower N layer 12 are connected by the side surface of the element separating insulating film 4. |
