Field shield isolation structure for semiconductor memory device and method for manufacturing the same

摘要

In a DRAM having stacked capacitor cells, elements are isolated by field shield isolating structure. The field shield isolating structure is formed surrounding both X and Y directions of the memory cell in the DRAM. The field shield isolating structure comprises an isolating electrode layer formed on a semiconductor substrate between adjacent memory cells with an insulating film interposed therebetween. Two impurity regions included in the adjacent memory cells and the isolating electrode layer constitute a MOS transistor. A voltage for maintaining the MOS transistor normally-off is applied to the isolating electrode layer. A portion of the stacked capacitor extends to the isolating electrode layer. One of the source/drain regions of the MOS transistor is formed in self-alignment, using a sidewall spacer formed of an insulating film on a sidewall of the field shield electrode as a mask.