Spread-vertical-capacitor cell (SVC) for high-density dRAM's

An advanced three-dimensionally (3-D) stacked-capacitor cell, the spread-vertical-capacitor cell (SVC), was developed. SVC realized a storage capacitance (C/sub s/) of 30 fF with a cell area of 1.8 mu m/sup 2/, a capacitor height of 0.37 mu m, and an equivalent SiO/sub 2/ film thickness of 7 nm for oxide-nitride-oxide (ONO). By extrapolating these results to 256-Mb DRAMs, a C/sub s/ of 24 fF is obtained with a cell area of 0.5 mu m/sup 2/, a capacitor height of 0.4 mu m, and an equivalent SiO/sub 2/ thickness of 5 nm, and these values satisfy the specifications for 256-Mb DRAMs. The low capacitor height of SVC makes possible a fabrication process using ArF excimer laser lithography.<
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