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.