| 摘要 |
PURPOSE:To improve data holding characteristic by a method wherein an Si substrate and a diffused region of a reverse conductivity type are formed in ring form in the circumference of a memory transistor (Tr), and the invading ion is gettered at this diffused region. CONSTITUTION:An oxide film 2 is formed at a part of the surface of the Si substrate 1. However, the region wherein the oxide film 2 is not formed is so provided in ring form as to surround the memory Tr. Next, the first gate Si oxide films 3a and 3b are formed by heat treatment. Then, the film 3b is removed, and the first polycrystalline Si film 4 is formed. Phosphorus implantation into the film 4 is performed, and accordingly a phosphorus diffused region 11 is formed at the ring region. The second gate Si oxide film 5 is formed, and then the second polycrystalline Si film 6 is formed. And, phosphorus is implanted into the film 6. The diffused layer of an impurity of a conductivity type reverse to that of the substrate 1 and an Si oxide film 8 are formed at a source and a drain region. |
