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

由于器件尺寸将继续低于20nm，并且新型纳米器件已经出现在市场上，因此对其电子结构的准确表征和详细理解是必不可少的，但也是具有挑战性的。特别是，纳米电容器和隧道势垒是大多数存储器的组成部分，由于其电容在阿托-法拉范围内，因此极难表征。最近开发的扫描微波显微镜（SMMs）几乎显示出这种能力，但它们的操作仅限于空气或氮气环境，由于众所周知的寄生水半月板的贡献，导致难以定量表征。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），已经提出了真空或超高真空版本，以消除这种寄生效应，同时也保护敏感器件。在这个项目中，我们首次提出建立一个真空下的SMM (VACSMM)，它将结合纳米级接触，成像，SEM观察和AFM尖端的FIB精炼，减少电寄生，直流和射频测量。它将配备一个干涉仪，允许aF电容灵敏度。10纳米以下的电容器和存储器将使用片上校准套件制造，以实现对这些器件的定量电子研究。特别是，将对电容，电导和开关速率（用于OxRAMs存储器）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，原子开关的物理学）。制造的VACSMM将共存于SEM内，自动化方法将作为一个视角，使该设备成为纳米级电容器和存储器表征的可能工业工具，然后再制造顶部电极。这个德法联合项目是一个很好的机会，可以结合纳米器件制造和SMM（法国合作伙伴）以及自制真空原子力显微镜/扫描电镜的互补专业知识，包括软件和机器人自动化工具（德国合作伙伴）。

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).