A 48nm 32Gb 8-level NAND flash memory with 5.5MB/s program throughput

Lower cost per bit and higher density NAND flash memory is a general trend in nonvolatile memory applications, such as MP3 players, digital still cameras, video camcorders, USB memories and solid-state disk. Technology scaling has become expected from consumers and recently higher number of bits per cell, such as 8-level cell or 16-level cell, is becoming a viable alternative solution due to difficulties in scaling. However, a higher number of bits per cell has two technical hurdles to overcome. One is low program throughput and the other is insufficient V_T-window margin. We design 32 Gb 8-level NAND flash memory with 5.5 MB/s program performance that addresses these problems. The memory has two planes with 2800 blocks per plane, 192 pages per each block, and 4 KB of data per page.