Vacuum Scanning Microwave Microscopy for quantitative characterization of sub-10 nm and atto-Farad scale capacitors and memories

由于器件比例将继续低于20纳米，而且新的纳米器件已经出现在市场上，准确地表征和详细了解它们的电子结构是必要的，但也是具有挑战性的。特别是，作为大多数存储器中的构建块的纳米电容器和隧道势垒，由于在atto-Farad范围内的电容而极难表征。最近发展起来的扫描微波显微镜(SMM)几乎显示了这种能力，但它们的工作仅限于空气或氮气环境，由于众所周知的寄生水弯月面贡献，导致很难进行定量表征。其他扫描探针显微镜(原子力显微镜、开尔文力显微镜、扫描隧道显微镜等)已经被提出了真空或超高真空版本，以消除这种寄生效应，但也可以保护敏感设备。在这个项目中，我们首次提出建立一个真空下SMM(VACSMM)，它将结合纳米级接触、成像、扫描电子显微镜观察和AFM尖端的FIB精炼，减少电寄生，DC和RF测量。它将配备一个干涉仪，允许自动对焦电容灵敏度。将使用片上校准套件制造10 nm以下的电容和存储器，以实现对这些器件的定量电子研究。特别是，将对OXRAM存储器的电容、电导和开关率进行统计研究，并提出模型/理论(有限元建模、S参数的分析模型、原子开关物理)。所制造的VACSMM将共存于扫描电子显微镜中，自动化方法将被开发为前景，使该装置可能成为在顶部电极制造之前的纳米级电容器和存储器表征的工业化工具。这个德法合作项目是将纳米器件制造和SMM(法国合作伙伴)和真空下自制原子力显微镜/扫描电子显微镜(包括软件和机器人自动化工具(德国合作伙伴))方面的互补专业知识结合在一起的绝佳机会。

As device scaling will continue below 20 nm and novel nanodevices already appear on the market, accurate characterization and detailed understanding of their electronic structure is essential, yet challenging. In particular, nanocapacitors and tunnel barriers, that are building blocks in most memories, are extremely difficult to characterize due to capacitances in the atto-Farad range. Recently developed Scanning Microwave Microscopes (SMMs) are almost showing such abilities but their operation, only limited to air or nitrogen environment, lead to difficult quantitative characterization due to well-known parasitic water meniscus contribution. Other Scanning Probe Microscopes (Atomic Force Microscopes, Kelvin Force Microscope, Scanning Tunneling Microscopes and other), have been proposed with vacuum or ultra-high vacuum versions to remove this parasitic effect, but also to protect sensitive devices.In this project, we propose to build, for the first time, a SMM under vacuum (VACSMM) that will combine nanoscale contact, imaging, SEM observation and FIB refining of AFM tips, reduced electrical parasitics, DC and RF measurements. It will be equipped with an interferometer allowing aF capacitance sensitivity. Sub-10 nm capacitors and memories will be fabricated with an on-chip calibration kit to achieve a quantitative electronic study on these devices. In particular, statistical studies will be performed on the capacitance, conductance and switching rates (for OxRAMs memories) and models/theory will be proposed (finite element modeling, analytical models for S parameters, physics of atomic switches).The fabricated VACSMM will coexist inside a SEM, automation methods will be developed as a perspective to make this apparatus a possible industrial tool for nanoscale capacitors and memory characterization before top electrode fabrication. This German-French joint project is a great opportunity to combine complementary expertise in nanodevices fabrication and SMM (French partner) and self-made Atomic Force Microscope/SEM under vacuum including software and robotic automation tools (German partner).