16-Gigabit, 8-level NAND flash memory with 51nm 44-cell string technology

Eight-level NAND flash memories with 51 nm design rule and 44-cell string floating gate technology have been successfully developed for the first time. 44-cell string with floating poly silicon and tungsten silicide (WSi) gate structure reduced the cell area per bit and improved chip cost efficiency. 44-cell string structure shows acceptable cell current and the results of endurance and interference are quite comparable to the conventional 32-cell string structure.