Regenerable Resistive Switching in Silicon Oxide Based Nanojunctions
Regenerable Resistive Switching in Silicon Oxide Based Nanojunctions
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DOI：
10.1002/adma.201104301
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发表时间：
2012-03-02
影响因子：
29.4
通讯作者：
Murgia, Mauro
中科院分区：
文献类型：
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作者：
Cavallini, Massimiliano;Hemmatian, Zahra;Murgia, Mauro
具有存储能力的新型超小型器件的开发是基础和应用研究中最热门的领域之一，因为现有的CMOS技术正在迅速接近其物理极限。[1，2]从这个角度来看，绝缘或半导体薄膜中的电阻开关[3]由于相应器件的多功能性和简单架构而受到极大关注，这些器件被称为“记忆电阻器”或“忆阻器”。[4-6]在最简单的配置中，忆阻器由夹在两个电极之间的绝缘或半导体薄膜组成，其中在施加高电场之后发生电阻切换。[4]薄膜可以是无机或有机的，并且通过使用磁性电极，忆阻器可以独立地执行电阻开关和磁阻开关。[7]忆阻器可以高速工作，适合于高密度集成，具有几个非易失性电阻状态，具有长的保持时间，以及低功耗。[8]由于所有这些原因，它们是纳米级存储器位单元中后CMOS技术最有可能的候选者之一。虽然忆阻器的概念在四十多年前由L. Chua [9]，在过去的几年里，由于薄膜和纳米纤维技术的巧妙结合，其应用才取得了突破。[6，10 - 12]忆阻器最近技术成功的关键点是使用标准，易于加工和充分研究的材料，器件的简单架构（例如，交叉结构）以及通过与微电子和纳米电子学中使用的当前技术兼容的稳健方法制造的可能性。[13尽管忆阻器正快速接近技术应用阶段，但一些主要问题仍未解决，即与磁存储相比的有限数量的编程-擦除循环以及串扰，串扰通过绝缘（半导体）薄膜和经由穿过交叉点的潜行路径两者发生。[15]即使是电阻开关的机制在大多数系统中仍然难以捉摸。[16]这些问题变得更加严格，当一个通过从微米到纳米尺度。在这里，我们提出了一个基于纳米忆阻器的原创系统，与传统器件相比，该系统提供了几个关键的技术和科学突破：i）在施加适当的电压周期时再生或修复结的可能性; ii）绝缘层的空间控制图案化，其在原位制造，防止通过薄膜的串扰问题; iii）可移除顶部电极的使用，其允许在切换之后暴露金属/薄膜界面的两侧的独特可能性以用于后续研究。我们在Si/SiO2/金属结上展示了我们的方法，其中SiO2通过局部氧化光刻原位制造;[17 - 19]这些材料通常用于硅基技术。[20]我们的系统的示意图描绘于图1中（参见实验部分中的详细描述）。将金属化印模放置在高湿度环境中与掺杂Si表面接触（图1a）。通过施加偏置电压（图1b），样品表面被氧化，形成完全适应印模特征的氧化膜。[21]的
The development of new ultraminiaturized devices with memory capabilities is one of the hottest fields in fundamental and applied research because the existing CMOS technology is rapidly approaching its physical limits.[1, 2] From this perspective, resistive switching [3] in insulating or semiconducting thin films is receiving great attention due to the versatility and simple architecture of the corresponding devices, which are called “memory resistors” or “memristors”.[4–6] In the simplest configuration a memristor consists of an insulating or semiconducting thin film sandwiched between two electrodes where the resistive switching occurs after the application of a high electric field.[4] The thin film can be either inorganic or organic and by using magnetic electrodes, memristors can independently perform both electrical and magnetic resistive switches.[7] Memristors can operate at high speed, are amenable to highdensity integration, have several nonvolatile resistive states with long retention times, and a low power consumption.[8] For all these reasons they are one of the most likely candidates for the post-CMOS technology in nanoscale memory-bit cells. Although the memristor concept was first proposed theoretically more than forty years ago by L. Chua,[9] a breakthrough towards its application has been achieved only in the last few years, thanks to the skillful combination of thin-film and nanofabrication techniques.[6, 10–12] The key points of the recent technological success of memristors are the use of standard, easily processable and well-studied materials, the simple architecture of the device (eg, crossbar structures) and the possibility to be fabricated by robust methods compatible with the current technology used in micro-and nanoelectronics.[13, 14] Despite the fact that memristors are quickly approaching the stage of technological application, some major problems remain unsolved, viz. the limited number of program-erase cycles compared to magnetic storage and the cross-talk, which occurs both through the insulating (semiconducting) thin film and via sneak paths through the cross-points.[15] Even the mechanism of resistive switching remains elusive in most systems.[16] These problems become more stringent when one passes from the micro-to the nano-scale. Here, we propose an original system based on nano-memristors that offers several crucial technological and scientific breakthroughs compared to conventional devices: i) the possibility to regenerate or repair the junction upon the application of an appropriate voltage cycle; ii) the spatially controlled patterning of the insulating layer, which is fabricated in situ, preventing the problems of cross-talk through the thin film; iii) the usage of removable top electrodes, which allow the unique possibility to expose the two sides of the metal/thin film interface after switching for subsequent investigation. We demonstrated our approach on a Si/SiO2/Metal junction where the SiO2 is fabricated in situ by local oxidation lithography;[17–19] these materials are commonly used in silicon-based technology.[20] A schematic drawing of our system is depicted in Figure 1 (see detailed description in the experimental section). A metalized stamp is placed in contact with the doped Si surface in a high-humidity environment (Figure 1a). By applying a bias voltage (Figure 1b) the sample surface is oxidized, forming an oxide film that perfectly adapts to the stamp features.[21] The