A Low Power Non-Volatile Memory Element Based on Copper in Deposited Silicon Oxide

Abstract

We describe the electrical characteristics of W-(Cu/SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> )-Cu switching elements formed by thermal diffusion of copper into deposited silicon oxide. These devices switch via the electrochemical formation of a conducting filament within the high resistance Cu/SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> electrolyte film. Unwritten and fully- erased devices of 350 nm to 1 mum in diameter transitioned from a high resistance state in excess of 100 MΩ to their on state at 1.3V or less, and the erase was initiated below -0.5V. The on resistance was a function of programming current and a range of approximately 2 MΩ to below 300 Ω was demonstrated. Switching was possible using 3V pulses of 1 mus duration and retention was good with no systematic upward drift evident beyond 105 s for devices programmed at 10 &3x003BC;A and read at 300mV. Endurance for 350nm diameter devices was determined to be in excess of 107 cycles.