Effects of Electric Fields on the Switching Properties Improvements of RRAM Device With a Field-Enhanced Elevated-Film-Stack Structure

Abstract

In this paper, a resistive random access memory (RRAM) device using a field-enhanced elevated-film-stack (EFS) structure with a 15-nm-thick HfO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> dielectric layer was fabricated and measured to achieve a forming voltage (V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Forming</sub> ) of 2.04 V, set voltage (V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Set</sub> ) of 0.95 V, and reset voltage (V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Reset</sub> ) of -1.22 V, compared to the values of 2.73 V, 1.26 V, and -1.54 V for the planar one with 6-nm-thick HfO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> , respectively. These resistive switching characteristics were effectively reduced, and the uniformity of these characteristics from device to device were considerably improved. The improvements of such an EFS-structured RRAM device were attributed to the high local electric fields at the two sharp corners of the EFS structure, which facilitated the formation of conductive filaments, and the distribution of the electric field was verified by technology computer-aided design simulations.