Observations on the “Universal Law” for NV Memory Cells

Photo of Ron Neale, Renowned Phase-Change Memory ExpertRon Neale returns to The Memory Guy blog to discuss a “Universal Law” about memory elements and selectors that was presented by CEA Leti at the IEEE’s 2019 IEDM conference last December.

At IEDM 2019 D. Alfaro Robayo et al presented a paper titled: Reliability and Variability of 1S1R OxRAM-OTS for High Density Crossbar Integration that had a rather interesting claim of a “Universal Law”.  It is possible that some links to the past might help to provide an explanation for Continue reading “Observations on the “Universal Law” for NV Memory Cells”

3D NAND: Making a Vertical String

Toshiba's Original BiCS Diagram - IEDM 2007Let’s look at how one form of 3D NAND is manufactured.  For this post we will explore the original design suggested by Toshiba at the IEEE’s International Electron Device Meeting (IEDM) in 2007.  It’s shown in the first graphic of this post.  (Click on any of the graphics for a better view.)

Toshiba calls this technology “BiCS” for “Bit Cost Scaling.”  The technique doesn’t scale the process the way the world of semiconductors has always done to date – it scales the cost without shrinking the length and width of the memory cell.  It accomplishes this by going vertically, as is shown in this post’s first graphic.

This takes a special effort. This is where the real Continue reading “3D NAND: Making a Vertical String”