Alternate metal virtual ground (AMG)-a new scaling concept for very high-density EPROMs

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- mu m technology is 2.56 mu m/sup 2/ and a 1- mu mm/sup 2/ cell is under development on a 0.5- mu m 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.<<ETX>>

[1]  Kuniyoshi Yoshikawa,et al.  An asymmetrical lightly-doped source (ALDS) cell for virtual ground high density EPROMs , 1988, Technical Digest., International Electron Devices Meeting.

[2]  A. Shubat,et al.  A new staggered virtual ground array architecture implemented in a 4Mb CMOS EPROM , 1989, Symposium 1989 on VLSI Circuits.

[3]  R. Lahiry,et al.  High density contactless, self aligned EPROM cell array technology , 1986, 1986 International Electron Devices Meeting.

[4]  S. Sweha,et al.  A 29ns 8Mb EPROM With Dual Reference-column ATD Sensing , 1991, 1991 IEEE International Solid-State Circuits Conference. Digest of Technical Papers.

[5]  M. Melanotte,et al.  A new self-aligned field oxide cell for multimegabit EPROMs , 1989, International Technical Digest on Electron Devices Meeting.

[6]  M. Okada,et al.  16Mb ROM design using bank select architecture , 1988, Symposium 1988 on VLSI Circuits.

[7]  Albert Fazio,et al.  A novel memory cell using flash array contactless EPROM (FACE) technology , 1990, International Technical Digest on Electron Devices.