AFM-based nano-machining: developing and validating a novel modelling approach for effective process implementation in nanotechnology applications

尽管光刻或扫描光束光刻是广泛用于制造具有纳米级特征的器件的技术，但仍然存在探索替代和互补的纳米级制造工艺的驱动力，特别是用于支持集成3D纳米结构的概念验证器件的开发。这是因为传统的纳米制造技术除了在制造真正的3D特征和可加工材料方面受到限制外，还依赖于资本密集型设备。此外，由于它们是能源和资源密集型的，并且会产生大量的废物，人们对它们的环境友好性也越来越关注。一种可能有助于解决这些限制的候选纳米制造工艺，特别是在纳米技术设备的开发阶段，依赖于原子力显微镜(AFM)探头尖端的机械加工。特别是，通过使用AFM探头尖端作为“纳米切割工具”，可以实现纳米级的材料去除操作。然而，AFM从业者目前不可能在没有完成实验试错活动的情况下确定所需的输入工艺参数，即尖端要施加的载荷和要遵循的切割方向，以实现特定的沟槽尺寸。为此，本项目旨在实现基于AFM的纳米加工的一种新的建模方法，以便在给定一组输入参数的情况下，用户可以预测加工槽的预期几何形状，反之亦然。为了实现这一总体目标，该项目将开发和验证基于AFM针尖的纳米加工过程的新的SPH-FE(即光滑粒子流体动力学-有限元)耦合模型。此外，为了确保这种过程建模基于可靠的数据，该项目建议采用新的实验表征技术来提取与纳米级切割特别相关的工件材料的机械性能。最后，该项目还旨在通过两个以实验室为基础的演示器，在应用拟议的建模方法时，展示这一纳米制造过程在开发和实施纳米技术应用方面的更大潜力。

Although photolithography or scanning beam lithography are techniques widely used for the fabrication of devices with nanoscale features, a drive still exists to explore alternative and complementary nanoscale manufacturing processes, particularly for supporting the development of proof-of-concept devices that integrate 3D nano-structures. This is due to the fact that conventional nanofabrication technologies rely on capital-intensive equipment in addition to being restricted in the fabrication of true 3D features and in the range of processable materials. Besides, there are also increased concerns over their environmental friendliness as they are energy and resource intensive and generate significant waste. One candidate nano-manufacturing process that may help address these limitations, particularly during the development stages of nanotechnology-enabled devices, relies on mechanical machining with the tip of an Atomic Force Microscope (AFM) probe. In particular, material removal operations on the nanoscale can be achieved as a result of using the AFM probe tip as a "nano-cutting tool". However, it is currently not possible for AFM practitioners to determine the required input process parameters, in terms of load to be applied by the tip and the cutting direction to be followed, for achieving specific groove dimensions without completing experimental trial-and-error campaigns first. For this reason, this project aims to implement a novel modelling approach of AFM-based nano-machining such that, given a set of input parameters, it will be possible for a user to predict the expected geometry of a machined groove, and vice versa. To achieve this overall aim, the project will develop and validate a new coupled SPH-FE (i.e. Smooth Particle Hydrodynamics - Finite Elements) model of the AFM tip-based nano-machining process. In addition, to ensure that such process modelling is based on reliable data, the project proposes to adopt novel experimental characterisation techniques to extract the mechanical properties of a workpiece material, which are specifically relevant for nanoscale cutting. Finally, the project also aims to demonstrate the increased potential of this nano-manufacturing process, when applied with the proposed modelling approach, for the development and implementation of nanotechnology applications through two lab-based demonstrators.