| 摘要 |
PURPOSE:To prevent a software error due to alpha-ray by individually altering the depths of a well of a peripheral circuit and a memory cell, thereby reducing the number of implantation to an inverting layer of induced electrons due to the alpha-ray. CONSTITUTION:In a memory cell, a shallow P type well 2 is formed, and NMOS memory cells 4-6 are formed in the well 2. In a peripheral circuit, a deep P type well 2' is formed, an N type substrate 1 is formed with PMOS 5, 6, and P type well 2' is formed with NMOS 4, 6. Accordingly, the P type well 2 of the memory cell can be shallowed to the degree that a punch-through is not produced, and the depth of the P type well 2' of a peripheral circuit can be formed to the degree that a latchup does not occur. |
