| 摘要 |
PURPOSE:To enhance the performance and the integration of a semiconductor device by forming a low density region only one of regions to become source and drain regions, thereby preventing the deterioration of the characteristics of an element. CONSTITUTION:The first gate oxide film 37, a floating gate electrode 38, the second gate oxide film 39 and a control gate electrode 40 are sequentially formed on a substrate 31. Then, with the electrode 40 as a mask As ions are implanted vertically directly from above, and with the electrode 40 as a mask As ions are implanted in high dosage. Subsequently, the impurity is activated by a heat treatment, an n type region 41 made of a low density diffused layer 41a near a channel region is formed on one side of the surface of the substrate 31, and an n<+> type region 42 made of a high density diffused layer is formed on the other side. Finally, electrodes 44, 45 are formed, and an EPROM cell is manufactured. |
