Department of Applied Physics, Eindhoven University of Technology, PO Box 513, 5600 MB Eindhoven, The Netherlands.
Nanotechnology. 2016 Sep 2;27(35):355301. doi: 10.1088/0957-4484/27/35/355301. Epub 2016 Jul 25.
To increase the efficiency of current electronics, a specific challenge for the next generation of memory, sensing and logic devices is to find suitable strategies to move from two- to three-dimensional (3D) architectures. However, the creation of real 3D nano-objects is not trivial. Emerging non-conventional nanofabrication tools are required for this purpose. One attractive method is focused-electron-beam induced deposition (FEBID), a direct-write process of 3D nano-objects. Here, we grow 3D iron and cobalt nanopillars by FEBID using diiron nonacarbonyl Fe2(CO)9, and dicobalt octacarbonyl Co2(CO)8, respectively, as starting materials. In addition, we systematically study the composition of these nanopillars at the sub-nanometer scale by atom probe tomography, explicitly mapping the homogeneity of the radial and longitudinal composition distributions. We show a way of fabricating high-purity 3D vertical nanostructures of ∼50 nm in diameter and a few micrometers in length. Our results suggest that the purity of such 3D nanoelements (above 90 at% Fe and above 95 at% Co) is directly linked to their growth regime, in which the selected deposition conditions are crucial for the final quality of the nanostructure. Moreover, we demonstrate that FEBID and the proposed characterization technique not only allow for growth and chemical analysis of single-element structures, but also offers a new way to directly study 3D core-shell architectures. This straightforward concept could establish a promising route to the design of 3D elements for future nano-electronic devices.
为了提高现有电子设备的效率，下一代存储器、传感器和逻辑设备的一个特定挑战是找到合适的策略，从二维（2D）架构向三维（3D）架构转变。然而，创造真正的 3D 纳米物体并非易事。为此目的需要新兴的非常规纳米制造工具。一种有吸引力的方法是聚焦电子束诱导沉积（FEBID），这是一种 3D 纳米物体的直接写入工艺。在这里，我们分别使用二羰基二铁 Fe2(CO)9 和二羰基八钴 Co2(CO)8 作为起始材料，通过 FEBID 生长 3D 铁和钴纳米柱。此外，我们通过原子探针断层扫描系统地研究了这些纳米柱在亚纳米尺度上的组成，明确地绘制了径向和纵向组成分布的均匀性。我们展示了一种制造直径约 50nm、长为数微米的高纯度 3D 垂直纳米结构的方法。我们的结果表明，这种 3D 纳米元件（Fe 纯度高于 90%，Co 纯度高于 95%）的纯度与其生长状态直接相关，在这种生长状态下，所选的沉积条件对纳米结构的最终质量至关重要。此外，我们证明了 FEBID 和所提出的表征技术不仅允许单元素结构的生长和化学分析，而且还提供了一种直接研究 3D 核壳结构的新方法。这个简单的概念可以为未来纳米电子设备的 3D 元件设计建立一条有前途的途径。
