Robust memory cell capacitor using multi-stack storage node for high performance in 90 nm technology and beyond

90 nm DRAM technology and beyond requires the robust memory cell capacitor structure in order to increase cell capacitance for high performance and low power applications. Thus, the cell technology must have the feature of high capacitance of memory cell capacitor while maintaining its mechanical stability. To accomplish these purposes, we develop the multi-stack storage node structure whose enlarged bottom size of OCS(One Cylindrical Storage node) can give much better mechanical stability of the capacitor than that of the conventional capacitor. Using Al/sub 2/O/sub 3//HfO/sub 2/ dielectric material together with this structure can give high cell capacitance 30fF/cell and low leakage current less than 1fA/cell.