面向接触共振原子力显微术亚表面成像的定量重构方法研究

微纳尺度各研究领域的深入发展对高分辨、无损、定量的亚表面成像技术提出迫切需求。面向这一需求，接触共振原子力显微术（CR-AFM）在诸多前沿领域展现出广阔的应用前景。然而，目前，基于CR-AFM的亚表面研究仍多为定性的成像观察，缺乏对亚表面结构进行定量分析的方法。针对此问题，本项目基于CR-AFM中亚表面结构衬度源于其引入的接触刚度变化的成像机理，开展面向亚表面结构等效弹性模量、尺寸及深度参量的定量重构方法研究。主要研究内容包括：分析亚表面结构目标重构参量与表面形貌因素对接触刚度的耦合影响规律，建立亚表面定量重构理论模型，并提出形貌因素解耦方法；发展基于作用载荷、探针刚度及振动模态等多实验参数调控的亚表面定量重构成像策略；探索亚表面三维图像重建方法，并开展面向半导体器件缺陷检测等的应用研究。本项目的实施可为纳米制造、纳米材料及纳米生物学各领域开展亚表面定量表征奠定理论与技术基础。

High resolution, nondestructive and quantitative subsurface imaging techniques are in surging demands in various fields at the micro- and nanoscale. Contact resonance AFM (CR-AFM) has demonstrated great potentials meeting the demands in many cutting-edge fields. However, subsurface imaging using CR-AFM are mostly mere qualitative observations at present, lacking methods for quantitative subsurface analysis. To address this issue, we propose in this project to develop a methodology for CR-AFM of reconstructing quantitatively the subsurface feature's reduced modulus, dimension and depth based on the subsurface imaging mechanism of contact stiffness sensing. The project is planned to carry out as follows. Firstly, apply in-depth analysis of the coupling effects of the subsurface feature's abovementioned properties and the surface topography on the contact stiffness, and build the theoretical models for subsurface reconstruction which decouple the topography effect. Secondly, develop experimental strategies aiming at quantitative subsurface reconstruction by modulating multiple experimental parameters, including the applied load, the cantilever stiffness and the working eigenmode. Finally, explore an approach of three-dimensional (3D) subsurface reconstruction, and carry out application researches such as for subsurface defect inspection in semiconductor structures. The proposed project is aimed to lay the theoretical and technical foundations for CR-AFM to achieve quantitative nondestructive testing applications in nanofabrication, nanomaterial and nanobiology studies.