| 摘要 |
PURPOSE:To improve a semiconductor memory device in the degree of integration by a method wherein RAM cells constituting a memory cell array of the semiconductor memory device are surrounded with a field shield isolating structure so as to be insulated and isolated. CONSTITUTION:A RAM 1 is composed of a transfer gate transistor (Tr) 2, a gate oxide film 12, a shield electrode layer 13, and a capacitor 3 formed on a semiconductor substrate 4. The RAM cell 1 is insulated and isolated by an element isolating region 16 of a field shield isolating structure composed of an impurity diffusion layer 5 of the Tr 2 and others which keeps the Tr 2 in an OFF-state always. The layer 5 is formed as being self-aligned to the region 16, a capacitor is extended to a position above a layer 13, whereby the RAM cell 1 is not required to be insulated and isolated using a thick oxide film, so that obstacles to high integration caused by a redundant region such as a bird's beak or the like can be completely eliminated and the RAM cell 1 can be easily and highly integrated. |
