A monolithic 64 Gb MLC NAND flash based on 21 <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex Notation="TeX">$~$</tex></formula> nm process technology has been developed. The device consists of 4-plane arrays and provides page size of up to 32 KB. It also features a newly developed asynchronous DDR interface that can support up to the maximum bandwidth of 400 MB/s. To improve performance and reliability, on-chip randomizer, soft data readout, and incremental bit line pre-charge scheme have been developed.