考虑摩擦力及试样表面倾角的原子力显微镜扫描模式

Operation Mode of AFM Considering Friction and Slope of Sample Surface

原子力显微镜(Atomic force microscopes,AFM)接触模式下的测量结果因受样本表面倾角和针尖—样本表面间摩擦力的影响而存在较大的测量误差。为避免针尖—表面间的摩擦力对AFM测量试样表面形貌的影响,并能够准确测量表面倾角,提出了一种新的AFM工作模式——消除倾角和摩擦力影响模式。在这种工作模式中,扫描方向垂直悬臂的长轴方向,通过测量悬臂的竖向和横向偏转而得到针尖所受的竖向和横向力,并计算得到针尖—试样表面间的vander Waals力及试样表面局部倾角,然后结合针尖顶点和扫描器的位置及针尖—试样表面间距可以得到试样表面形貌的测量结果。在上述工作模式下,针尖—试样表面间的摩擦力是可控的,能够避免针尖或试样的损伤。仿真结果证明了这种方法的可行性。

The measurement result of AFM＇s contact mode has big measurement error due to the inclination angle of sample surface and friction between the tip and sample surface. In order to eliminate the influence of the friction on the sample topography measured by AFM, and to measure the slope of surface accurately, a novel AFM operation mode that can eliminate the influence of inclination angle and friction （EIIAF）, is presented. In this mode, the scan direction is vertical to the long axis of cantilever. By measuring the deflection of cantilever separately in vertical and lateral directions, the forces added to the tip in the two directions can be easily obtained. And then the van der Waals force and the slope of local surface can be obtained by calculating the two forces. By synthesizing the calculated parameters with other parameters, such as the location of tip and scanner the space between the tip and sample surface, the sample＇s topography can be finally obtained. In the above operation mode, the friction force between tip and sample surface can be controlled, thus the damage to tip and sample can be avoided. And the feasibility of this method is verified by the simulation results.