A 117-MM(2) 3.3-V ONLY 128-MB MULTILEVEL NAND FLASH MEMORY FOR MASS-STORAGE APPLICATIONS

For a quantum step in further cost reduction, the multilevel cell conc ept has been combined with the NAND flash memory, Key requirements of mass storage, low cost, and high serial access throughput have been ac hieved by sacrificing fast random access performance. This paper descr ibes a 128-Mb multilevel NAND flash memory storing 2 b per cell. Multi level storage is achieved through tight cell threshold voltage distrib ution of 0.4 V and is made practical by significantly reducing program disturbance by using a local self-boosting scheme, An intelligent pag e buffer enables cell-by-cell and state-by-state program and inhibit o perations, A read throughput of 14.0 MB/s and a program throughput of 0.5 MB/s are achieved, The device has been fabricated with 0.4-mu m CM OS technology, resulting in a 117 mm(2) die size and a 1.1 mu m(2) eff ective cell size.