Department of Materials Science and Engineering, and Inter-University Semiconductor Research Center , Seoul National University , Seoul 08826 , Republic of Korea.
ACS Appl Mater Interfaces. 2018 Jun 27;10(25):21445-21450. doi: 10.1021/acsami.8b05031. Epub 2018 Jun 15.
The high nonuniformity and low endurance of the resistive switching random access memory (RRAM) are the two major remaining hurdles at the device level for mass production. Incremental step pulse programming (ISPP) can be a viable solution to the former problem, but the latter problem requires material level innovation. In valence change RRAM, electrodes have usually been regarded as inert (e.g., Pt or TiN) or oxygen vacancy (V) sources (e.g., Ta), but different electrode materials can serve as a sink of V. In this work, an RRAM using a 1.5 nm-thick TaO switching layer is presented, where one of the electrodes was V-supplying Ta and the other was either inert TiN or V-sinking RuO. Whereas TiN could not remove the excessive V in the memory cell, RuO absorbed the unnecessary V. By carefully tuning (balancing) the capabilities of V-supplying Ta and V-sinking RuO electrodes, an almost invariant ISPP voltage and a greatly enhanced endurance performance can be achieved.
高非均匀性和低耐久性是阻变随机存取存储器（RRAM）在器件级大规模生产中仍然存在的两个主要障碍。增量阶跃脉冲编程（ISPP）可以解决前一个问题，但后一个问题需要材料层面的创新。在价态变化 RRAM 中，电极通常被认为是惰性的（例如，Pt 或 TiN）或氧空位（V）源（例如，Ta），但不同的电极材料可以作为 V 的汇。在这项工作中，提出了一种使用 1.5nm 厚 TaO 开关层的 RRAM，其中一个电极是提供 V 的 Ta，另一个电极是惰性 TiN 或 V 吸收 RuO。虽然 TiN 不能去除存储单元中的过量 V，但 RuO 吸收了不必要的 V。通过仔细调整（平衡）提供 V 的 Ta 和吸收 V 的 RuO 电极的能力，可以实现几乎不变的 ISPP 电压和大大增强的耐久性性能。
