Performance Enhancement of Ag/HfO2 Metal Ion Threshold Switch Cross-Point Selectors

A metal ion threshold switch (MITS) based on an Ag/TiN/HfO
₂
/Pt stack is experimentally demonstrated with improved endurance. The incorporation of a low-temperature atomic layer deposition (ALD) TiN layer as an efficient diffusion barrier enables optimum Ag infiltration during the electroforming step. Further, the tunability of the threshold voltage (V
_TS
) from 0.25 to 1.1V via bottom electrode (BE) work function engineering is demonstrated. The Ag/TiN/HfO
₂
/Al MITS selector exhibits a 4.4× increase in V
_TS
, 100 μA ON-current handling capability, low leakage (~10 pA), 10
⁷
half-bias non-linearity and fast (<; 30 ns) turn-ON switching speed. The turn-OFF speed of the selector device is independent of the built-in field, indicating that the latter does not influence ionic relaxation during the filament rupture process.