A CELL MODEL FOR NON-VOLATILE RANDOM ACCESS MEMORY AND A SUBSEQUENT METHOD FOR INCREASING DENSITY

ABSTRACT

A cell model for non-volatile random access memory (RAM) is suggested in this study. An indicator, a cell, was introduced to simplify the explanation. If the indicator is good, then the device to which it belongs is acceptable. An inequality acquired through modeling a cell can determine whether a cell is good or not. To satisfy the pass condition, the energy barrier for storage (Eb), the sum of uniformities (uniformity of non-volatile material (Ui), uniformity related to the relative position of a data cell and a reference cell (Us)), and the sensing signal margin (Vsm) must be high. The inequality means that e^EbUie^EbUs Vsm is larger than a constant. If the parameters of an indicator satisfy the inequality condition, the device will be acceptable. As any general property of the cell changes, the indicator's property will also change accordingly. As cell density increases, inequality will not be satisfied due to decreasing Ui. A new cell that can be predicted with the model is suggested. Increasing Eb for data storage and decreasing Eb for data transition seems to be necessary to increase the cell density of non-volatile RAM. Eb of non-volatile material is controlled by metallic lines in a new cell.

Keywords::

• Non-volatile RAM
• non-volatile material
• indicator
• cell
• cell model
• energy barrier
• uniformity
• signal margin
• inequality
• cell density
• new cell

Acknowledgments

Paper originally presented at ISIF-18, Honolulu, Hawaii, April 23–27, 2006. The original Proceedings of the Eighteenth International Symposium on Integrated Ferroelectrics (ISIF-18) are published in seven earlier volumes of INTEGRATED FERROELECTRICS (Volumes 84–90, inclusive).