1. Field of the Invention
This invention pertains to an improvement in a semiconductor memory device, such as a DRAM (dynamic random access memory), SRAM (static random access memory), EEPROM (electric erasable and programmable read only memory) and other semiconductor devices requiring sufficient storage capacitance such as an analog IC with capacitance.
2. Background of the Invention
DRAM has become more and more minuscule in recent years. Thus, the area occupied by a single memory cell has decreased. To obtain a stable DRAM relative to soft errors, a storage capacitance of a sufficient value must be formed in this tiny area. Accordingly, various three dimensional memories, e.g. a stacked type of memory, a trenched type of memory, a crown type of memory, and a cylinder type of memory, have been put into use. Yet, a number of problems still remain to be solved to form memories having such structures.