动态原子力显微镜(atomic force microscope, AFM)是通过检测悬臂谐振状态的变化来对物体表面形貌进行测量的。通过对谐振状态的三种因素即振幅、相位、频率的检测, 动态AFM可以分为三种工作模式, 即振幅反馈、相位反馈与频率反馈模式, 这三种反馈模式有着不同的扫描特点。基于硅悬臂具有高阶谐振的特性, 动态原子力显微镜可以在悬臂工作于高阶谐振状态时对物体进行扫描。综合上述工作模式研制了一套多模态动态AFM, 可以在三种反馈模式、不同阶谐振状态下对物体进行扫描测量。利用该系统在不同反馈模式、不同阶谐振状态下进行了扫描测试, 结果显示, 系统在各模式下具有亚纳米分辨力, 其中在相位反馈模式, 悬臂二阶谐振时可达到最优灵敏度与分辨力, 分别为17.5V/μm和0.29nm, 在最优灵敏度与分辨力状态下对光栅试样进行了三维扫描, 得到光栅的三维形貌图。

Dynamic atomic force microscope (AFM) is able to measure the surface topography of objects by detecting the changes of resonance state of the cantilever. Through the detection on three factors of such resonance state, amplitude, phase and frequency, dynamic AFM could be divided into three kinds of working modes, which are amplitude feedback mode, phase feedback mode and frequency feedback mode, and such feedback modes have different scanning characteristics. Based on the higher-order resonance characteristics of the silicon cantilever, dymamic AFM is able to scan objects when the cantilever is working under the high-order resonance. By combining above working modes, a multi-mode dynamic AFM was developed, which could scan and measure the objects under the above three feedback modes and different order of resonance state. The results of scanning tests under different feedback modes and different order of resonance state by application such system show that the system has sub nanometer resolution in each working mode, in which the system can achieve the optimal sensitivity and resolution under phase feedback mode and when the cantilever runs under the second order resonance, which is 17.5V/μm and 0.29nm respectively. Uuder such optimal sensitivity and resolution, the three dimensional scanning test of grating is conducted to obtain its 3D topography image.