WOx-RRAM的制备及阻变机理探索
发布时间：2019-07-09 17:45
【摘要】：近年来，由于存储市场的巨大需求，非挥发性存储技术发展迅速，基于浮栅结构的传统Flash存储器在集成电路工艺中特征尺寸已经接近甚至达到其物理极限，发展遇到瓶颈。在各种新型非挥发性存储器中，阻变存储器（RRAM）以其简单的存储单元结构、可缩小化的特征尺寸、极快的读写速度、很低的器件功耗、多值存储潜力、可三维堆叠，以及低成本等特点，受到了广大科研工作者的关注。本文主要研究一种与CMOS工艺兼容，制备容易的WOx基RRAM，探寻改善器件性能，降低器件功耗的方法，并对器件的阻变机制作了初步分析。 本文使用金属钨靶采用直流反应磁控溅射沉积氧化钨薄膜，并利用X射线衍射仪（XRD）、原子力显微镜（AFM）等手段对氧化钨薄膜的结晶取向及表面形貌进行了表征；使用半导体参数分析仪（SPA）对阻变单元的非挥发存储特性进行测试，通过对置位（SET）、复位（RESET）过程的I-V曲线进行线性拟合结合电阻的温度依赖性对氧化钨薄膜的电阻转变机制进行了探索。 主要研究内容及结果如下： 1、基于氧化钨材料制备了简单的Al/WOx/Cu结构RRAM。WOx膜在300℃退火后，以（110）晶相的WO2.9为主。器件具有较好的双极阻变特性，有较小的操作电压（Vset=1.6V, Vreset=-0.9V）及超过三个数量级的阻变倍率。有较好的耐擦写特性（1000cycles）、电阻保持性(10000S)。WOx薄膜中形成的Cu细丝及Cu细丝数量的变化是薄膜电阻转变的主导机制。 2、通过对Cu下电极进行热氧化处理，制备了叠层结构的Al/WOx/CuOx/Cu RRAM。与单层结构相比，叠层结构有更高的成品率，接近100%；更低、更一致的Forming电压、SET、RESET电压，更小的操作电流；器件的功耗降低了四个数量级以上。器件的电阻转变机制为低阻态时阻变层中形成了Cu细丝，高阻态时Cu细丝与阴极接触处部分断开，在电极与阻变层界面处形成肖特基势垒，器件的电流传输主要为肖特基发射。 3、在Cu下电极热氧化处理时间为30S，WOx膜制取氧氩流量比为25:55sccm时，成功制备了单极型的Al/WOx/CuOx/Cu结构RRAM。器件有较好的非挥发存储特性，且是Forming-free器件。通过对电流的传导机制进行分析，发现低阻态时器件阻变层中形成了氧空位导电细丝，高阻态时氧空位导电细丝断开，器件的电流传输由空间电荷限制电流效应（SCLC）主导。
文内图片：
图片说明：MRAM单元的结构示意图
[Abstract]:In recent years, due to the huge demand of storage market, non-volatile storage technology has developed rapidly. The characteristic size of traditional Flash memory based on floating gate structure in integrated circuit technology has approached or even reached its physical limit, and the development has encountered a bottleneck. Among all kinds of new non-volatile memory, resistive memory (RRAM) has attracted the attention of many researchers because of its simple memory cell structure, reduced characteristic size, very fast reading and writing speed, low device power consumption, multi-valued storage potential, 3D stacking, and low cost. In this paper, a WOx-based RRAM, which is compatible with CMOS process and easy to fabricate is studied to explore the method of improving device performance and reducing device power consumption, and the resistance mechanism of the device is preliminarily analyzed. Tungsten oxide thin films were deposited by DC reactive magnetron sputtering with tungsten target. The crystallization orientation and surface morphology of tungsten oxide thin films were characterized by X-ray diffractometer (XRD), atomic force microscope (AFM). The non-volatile storage characteristics of resistance unit were tested by semiconductor parameter analyzer (SPA). The resistance transition mechanism of tungsten oxide thin films was explored by linear fitting of I 鈮，
本文编号：2512321
文内图片：
图片说明：MRAM单元的结构示意图
[Abstract]:In recent years, due to the huge demand of storage market, non-volatile storage technology has developed rapidly. The characteristic size of traditional Flash memory based on floating gate structure in integrated circuit technology has approached or even reached its physical limit, and the development has encountered a bottleneck. Among all kinds of new non-volatile memory, resistive memory (RRAM) has attracted the attention of many researchers because of its simple memory cell structure, reduced characteristic size, very fast reading and writing speed, low device power consumption, multi-valued storage potential, 3D stacking, and low cost. In this paper, a WOx-based RRAM, which is compatible with CMOS process and easy to fabricate is studied to explore the method of improving device performance and reducing device power consumption, and the resistance mechanism of the device is preliminarily analyzed. Tungsten oxide thin films were deposited by DC reactive magnetron sputtering with tungsten target. The crystallization orientation and surface morphology of tungsten oxide thin films were characterized by X-ray diffractometer (XRD), atomic force microscope (AFM). The non-volatile storage characteristics of resistance unit were tested by semiconductor parameter analyzer (SPA). The resistance transition mechanism of tungsten oxide thin films was explored by linear fitting of I 鈮，
本文编号：2512321
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