A Multi-page Cell Architecture For High-speed Programming Multi-level NAND Flash Memories

To realize low-cost, highly reliable, high-speed pro- gramming, and high-density multilevel flash memories, a mul- tipage cell architecture has been proposed. This architecture enables both precise control of the of a memory cell and fast programming without any area penalty. In the case of a four-level cell, a high programming speed of 236 s/512 bytes or 2.2 Mbytes/s can be obtained, which is 2.3 times faster than the conventional method. A small die size can be achieved with the newly developed compact four-level column latch circuit. A preferential page select method has also been proposed so as to improve the data retention characteristics. The IC error rate can be decreased by as much as 43%, and a highly reliable operation can be realized.