Effect of bottom electrode of ReRAM with Ta<inf>2</inf>O<inf>5</inf>/TiO<inf>2</inf> stack on RTN and retention

Abstract

The Effect of the bottom electrode of ReRAM with a Ta <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sub> /TiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> 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 <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> 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).