A 98 mm/sup 2/ die size 3.3-V 64-Mb flash memory with FN-NOR type four-level cell

In order to realize high-capacity and low-cost flash memory, we have developed a 64-Mb flash memory with multilevel cell operation scheme. The 64-Mb flash memory has been achieved in a 98 mm/sup 2/ die size by using four-level per cell operation scheme, NOR type cell array, and 0.4-/spl mu/m CMOS technology. Using an FN type program/erase cell allows a single 3.3 V supply voltage. In order to establish fast programming operation using Fowler-Nordheim (FN)-NOR type memory cell, we have developed a highly parallel multilevel programming technology. The drain voltage controlled multilevel programming (DCMP) scheme, the parallel multilevel verify (PMV) circuit, and the compact multilevel sense-amplifier (CMS) have been implemented to achieve 128 b parallel programming and 6.3 /spl mu/s/Byte programming speed.