Ultra-Scaled AlOx Diffusion Barriers for Multibit HfOx RRAM Operation

For dense very large scale integration (VLSI) of high performance, multibit resistive memory (RRAM), scalability of material dimensions, as well as the operational sensitivity of the RRAM to voltage fluctuations, have to be considered. This report presents the benefits of adding 0.5-nm thick AlO
_x
diffusion barriers at the different electrode interfaces of HfO
_x
. It is found that implementing AlO
_x
-layers at both the bottom and the top electrode interface enables a tight control of the oxygen vacancy filament, resulting in low switching voltages and significantly improving switching endurance up to 10
⁶
cycles using a performance limiting resistor compliance. It is also shown that the filament in its low resistive state ( R
_LRS
) can be linearly reduced and enlarged at levels compatible to the conduction limitations of scaled selectors using an external 1T1R transistor compliance. With selector controlled resistance modulation, the R
_LRS
becomes independent of the magnitude of the programming voltage and thus less sensitive to losses throughout a large memory array.