A 2.3 mu m/sup 2/ memory cell structure for 16 Mb NAND EEPROMs

A NAND structure memory cell with 2.2*1.05 mu m/sup 2/ size per bit, based on a 0.6 mu m design rule, has been developed for 16 Mb flash EEPROMs. The cell size is about 64% of the smallest 16 Mb EPROM cell so far reported. An extremely small cell can be realized by the following technologies: (1) newly developed 0.3 mu m space self-aligned stacked gate patterning, (2) a NAND structured cell array which contains 16 memory transistors in series, and (3) high-voltage field isolation technology used to isolate neighboring bits. The first and second technologies reduce the length of the cell by 67.6% compared with the conventional NAND structured cell using the same design rule, while the third technology reduces the width by 84.6%.<
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