Annealing Effect on the Performance of Copper Oxide Resistive Memory Devices
Chih-Chieh Hsu, Yu-Sheng Lin, Chao-Wen Cheng, Wun-Ciang Jhang
Abstract
In this article, the annealing effect on resistive switching (RS) characteristics of Al/CuO/indium tin oxide (ITO) resistive random access memory (RRAM) devices is investigated. The RRAM performance is highly sensitive to the annealing temperature of the CuO RS layer. RS characteristics are not observed in the device that uses the as-fabricated CuO film as the active layer. When an annealing process at 250 °C is applied to the CuO layer, bipolar RS behavior is found. However, the resistance ratio of the high resistance state (HRS) to the low resistance state (LRS) is a low value:18. A dramatic improvement in the resistive window can be obtained when the annealing temperature increases to 350 °C. A stable resistive window of 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sup> is observed for over 250 switching cycles. Data retention and read disturb tests for 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sup> s are performed to verify the nonvolatility and the data retention capability. Degradation in the RS characteristics is found when the annealing temperature further increases to 400 °C. The performance variation caused by different annealing temperatures is explained by differences in the crystallinities, grain sizes, and defect densities of the CuO RS layers.