Effect of bottom electrode of ReRAM with Ta2O5/TiO2 stack on RTN and retention

The Effect of the bottom electrode of ReRAM with a Ta
₂
O
₅
/TiO
₂
stack on noise and retention was investigated. The current fluctuation due to complex random telegraph noise (RTN) resulted in errors in the read-out with multi-level operation. We clarified that the Ti diffusion into the TiO
₂
layer from the bottom electrode increased the trap density and thus degraded current stability. The increased density caused the minority bit in the reset state to fail under a high temperature stress. The use of a stack with a Ru or Pt electrode with controlled Ti diffusion resulted in low noise and high thermal stability (>190°C).