Alternate metal virtual ground (AMG)--A new scaling concept for very high-density EPROM'S

A new erasable programmable read-only memory (EPROM) array concept that reduces the cell size to the poly pitch in both directions is introduced. The key concepts that made the dramatic scaling possible are the virtual ground array with one metal line for every two diffusion bit lines, the segmentation of every other bit line, and the fieldless array. The cell size on 0.8-μm technology is 2.56 μm2 and a 1-μm2 cell is under development on a 0.5-μm technology for the 64-Mb product. These cells are smaller by a factor of 2-3 than the standard EPROM cell on the same technology. The new array concept and its advantages are expandable to flash memories.