CAREER: Quantitative Ultrasonic Atomic Force Microscopy of Thin Films and Subsurface Interfaces

原子力显微镜（AFM）已经成为纳米科学和纳米技术中不可或缺的工具，它使用具有锋利尖端的软杠杆非破坏性地提供优异的横向和垂直表面形貌分辨率。然而，为了探测固体表面的机械特性并获得关于表面下界面和缺陷的信息，AFM悬臂梁需要更硬。人们可以通过在超声波频率下振动AFM悬臂来增加AFM的有效刚度，同时在低DC或轻敲接触力的情况下保持出色的横向分辨率。这项研究的目的是探讨潜在的超声波原子力显微镜技术的非破坏性，定量测量薄膜材料的性能和接口，更具体地说，在电子互连结构和其他纳米器件的亚表面缺陷的原位成像。拟议的创新研究计划有以下具体目标：（a）开发AFM悬臂尖端与图案化表面和超声波频率下的表面下缺陷的相互作用的理论模型，（B）开发将轻敲模式成像与超声波AFM相结合的测量方法，以具有与样品的可重复的间歇接触力，用于定量的原位测量，和超声波AFM，以纳米级向样品表面施加剪切应力，以增强对界面缺陷的灵敏度。此外，这些技术将被应用在流体环境中的生物和化学应用，使用声辐射压力驱动的AFM杠杆。教育发展计划的重点是通过指导参与研究生和本科生，支持高中学生科学项目和K-12教育工作者，为当地K-12教育机构和格鲁吉亚理工学院之间的合作伙伴关系计划做出长期贡献。从少数民族和代表性不足的群体中选出的本科生研究助理将参与研究项目，以及来自不同学科的研究生。除了在纳米技术领域的学生动手培训，扫描探针显微镜研究生水平的课程将与其他教师在格鲁吉亚技术合作开发。

The atomic force microscope (AFM) has become an indispensable tool for nanoscience and nanotechnology providing excellent lateral and vertical surface topography resolution non-destructively using soft cantilevers with sharp tips. To probe the mechanical properties of solid surfaces and obtain information about subsurface interfaces and defects, however, the AFM cantilever needs to be stiffer. One can increase the effective stiffness of the AFM by vibrating the AFM cantilever at ultrasonic frequencies surfaces while maintaining the outstanding lateral resolution with low DC or tapping contact force. This research proposal aims to investigate the potential of ultrasonic AFM techniques for non-destructive, quantitative measurements of thin film material properties and interfaces, and more specifically, for in-situ imaging of subsurface defects in electronic interconnect structures and other nanoscale devices. The proposed innovative research plan has the following specific aims: (a) Development of theoretical models of the interactions of the AFM cantilever tip and patterned surfaces and subsurface defects at ultrasonic frequencies, (b) Development of measurement methods combining tapping mode imaging with ultrasonic AFM to have repeatable, intermittent contact force with the samples for quantitative, in-situ measurements, and an ultrasonic AFM to apply shear stresses to the sample surface at the nanoscale for enhanced sensitivity to interface defects. Furthermore, these techniques will be applied in fluidic environments for biological and chemical applications using acoustic radiation pressure actuation of AFM cantilevers. The educational development plan is focused on long-term contributions to the partnership programs between the local K-12 education institutions and Georgia Tech through mentoring of participating graduate and undergraduate students, supporting high school student science projects, and K-12 educators. Undergraduate research assistants selected from minorities and underrepresented groups will be involved in the research project as well as graduate students from different disciplines. In addition to hands on training of students in the nanotechnology area, a graduate level course on Scanning Probe Microscopy will be developed in collaboration with other faculty members at Georgia Tech.