ECCS - EPSRC Development of uniform, low power, high density resistive memory by vertical interface and defect design

节能计算的未来将越来越多地从以计算为中心转向以内存为中心。存储和移动数据需要消耗大量的能量，这比计算数据要高得多。事实上，在数据密集型应用程序中，内存占据了计算能量的主导地位（> 4倍）。新型超低功耗非易失性存储器（NVM）是计算各个方面的核心，从用于数据中心的独立存储类存储器（SCM）到用于物联网、汽车行业等的嵌入式非易失性存储器（e-NVM），再到新的计算形式。该领域正在巨大增长，沿着相关的能源消耗，例如，到2030年，数据中心将使用全球电力的10%以上，市场每年增长约10%，到2023年将达到1500亿美元。由于摩尔定律已接近尾声，而且新的处理器技术尚未建立，因此这种效率不可能来自于处理。最大的性能和节能收益将在内存中。用高性能存储器NVM替代标准存储器可以降低60%以上的功耗。在众多的NVM候选形式中，氧化物电阻RAM（RRAM）在成本、密度、简单性和3D集成潜力方面具有最大的潜力。然而，目前存在几个挑战，特别是需要成形电压、差的均匀性、缩放和耐久性。该项目的目的是克服这些挑战。这将通过采用我们从理想系统到行业平台的突破性成果来实现。到目前为止，在理想系统中，我们已经证明了a）精确和非随机的导电通道可以被设计到膜中以消除对高电压形成过程的需要; B）高且受控的氧空位浓度导致高度和可再现的开-关比; c）消除过渡金属的使用产生低泄漏并且强烈地降低膜与膜之间的可变性。我们将在这个项目中探索的工业平台是掺杂的HfO 2，通过溅射和原子层沉积生长。一个在提案领域有着超过15年强有力合作的国际领先团队将承担这项工作。首先，使用脉冲激光沉积（PLD）的货车膜的生长将在普渡大学进行。PLD是快速制备最完美的金属氧化物薄膜的最简单的方法。这些将使我们能够更全面地了解RS过程，并将提供有关如何通过工业规模化过程生长薄膜的信息。普渡大学和剑桥大学都将参与PLD用HfO 2纳米结构薄膜的设计。PLD生长的知识将转化为剑桥大学采用的溅射和ALD方法。布法罗大学的工作将集中在使用普渡大学和剑桥大学沉积的RS薄膜制造和测试原型忆阻器和RRAM。最先进的（一些在操作中）表征工具也将是材料理解和设备优化的核心，这些工具将在普渡大学和剑桥大学使用。小组之间将进行非常强烈的互动，定期进行样本和知识转移。我们的最终目标是一个无成型的器件，开/关比~104，耐久性>1012，每个开关<10 pJ，均匀性为几个百分点，规模为20纳米。在培训方面，我们将培养材料科学和电子工程专业的毕业生。我们将在美国和英国的世界领先的研究环境中培训3名以上的早期职业研究人员，涉及多家公司（从小到大），包括剑桥公司ARM，他们在英国和美国都非常活跃，在内存领域。

The future of energy-efficient computing will increasingly move from being compute-centric to being memory-centric. There is a huge-energy cost of storing and moving data, which is much higher than computing it. Indeed, memory dominates compute energy (>4X) in data-intensive applications. New ultralow power non-volatile memory (NVM) is central to all aspects of computing, from stand-alone, storage class memory (SCM) for use in data centres, to embedded non-volatile memory (e-NVM) for IoT, the automotive industry, etc, to new forms of computing. The area is growing hugely, along with the associated energy consumption, e.g. data centers will use >10% of global electricity by 2030 with a market growing ~10% per year, to >$150 billion by 2023. Such efficiency cannot come from processing as Moore's law reaches an end and new processor technologies are not yet established. The biggest performance and energy saving gains will be in memory. The replacement of standard memory with high performance memory NVM could reduce power usage by more than 60%.Of the many candidate NVM forms under intense investigation, oxide resistive RAM (RRAM) has the greatest potential in terms of cost, density, simplicity and potential for 3D integration. However, several challenges currently exist, notably the need for a forming voltage, poor uniformity, scaling, and endurance. The aim of this project is to overcome these challenges. It will be done by adopting our ground-breaking results from an ideal system to an industry platform. So far, in the ideal system, we have demonstrated that a) precise and non-random conducting channels can be engineered into films to eliminate the need for a high voltage forming process; b) high and controlled oxygen vacancy concentrations lead to highly and reproducible on-off ratios; c) eliminating use of transition metals produces low leakage and strongly reduces variabilities from film to film. The industry platform we will explore in this project is doped HfO2, grown by sputtering and atomic layer deposition. An internationally leading team with more than 15 years of very strong collaboration in the area of the proposal will undertake the work. First, growth of VAN films using pulsed laser deposition (PLD) will be undertaken at Purdue University. PLD is the simplest way to make the most perfect metal oxide films in a rapid way. These will enable us to understand the RS processes more fully and will provide information on how to grow the films by the industrially scaleable processes. Both Purdue and Cambridge will be involved in the HfO2 nanostructure film design for PLD. The knowledge from the PLD growth will then be translated to the sputtering and ALD approaches undertaken at the University of Cambridge. The effort at the University at Buffalo will focus on the fabrication and testing of prototype memristors and RRAMs using the RS films deposited by Purdue University and University of Cambridge. State-of-the art (some in-operando) characterisation tools will also be central to materials understanding and device optimisation and these will be used at Purdue and Cambridge. A very strong interaction between the groups, with regular sample and knowledge transfer will take place. Our ultimate goal is a forming free device, with on/off ratio~104, endurance >1012, <10pJ per switch, uniformity of few %, scaled to 20 nm.In terms of training, we will educate graduates in materials sciences and electronic engineering. We will train more than 3 early career researchers in world-leading research environments in the US and UK, with several companies involved (small to large), including the Cambridge company ARM who are very active, both in the UK and US, in the memory area.