Influence Of AFM Probe Tip Radius Change On Nanoscale Surface Measurement

Atomic force microscopy (atomiac force microscopy, AFM) is ultra-precision machinery and electronic equipment, and it is a typical electromechanical integration equipment. In the mechanical field, it can be used in precision machining microstructure on the surface of the test; in the field of micro-electromechanical system, it can be applied to the detection of Nano mechanical properties testing. However, during atomic force microscopy surface detection, the probe tip is inevitable wears when the Probe tip is scanned in contact with the specimen surface, and an atomic force microscope is very easy to wear sharp tip, so that the probe tip radius of curvature changes, the tip radius of curvature reflects wear degree. With the change in the radius of curvature of the tip, on the one hand it produces the impact force between the tip and the surface; on the other hand have an impact on the geometric surface morphology detection. Therefore, the wear of the probe directly affects the accuracy and image quality of the surface measurement. After the tip is necessary to study the wear, the force between the tip and the surface variation of different radius of curvature change rule between the tip and surface forces and to examine the effects of the surface geometry morphology.This topic from the National Natural Science Foundation Project:" Micro mechanical friction pair contact mechanics behavior of multi-scale coupling analysis method study." Research AFM probe tip due to wear different between the probe tip radius of curvature (representing different degree of wear of the probe) in contact with the surface of the nano-scale process variation of the force of impact on the surface topography detection geometry.Firstly, in the analysis of atomic force microscopy and nano-contact force works on the basis of the calculation model, based on the assumption Hamaker using continuum methods established with the sample surface nano-tip contact force calculation model close process; according to Hertzian contact theory, the tip in contact with the surface of the sample calculation model of the contact pressure force into the process. By superimposing calculation process to obtain the coupling and close contact during press-contact force calculation method. According to the calculation model, using Matlab programming calculated the tip and the sample surface nano-contact force variation.Secondly, the use of three-dimensional molecular dynamics simulation of different radius of curvature of the tip in contact with the single-crystal copper matrix material in the wear mechanisms are analyzed in depth at a certain contact, different contact forces at different radius of curvature of the probe, leading deformation of the material forming the base is not the same dislocation.Finally, the use of an atomic force microscope probe wear after study, the impact of different probe tip radius of curvature of the surface quality and surface contact force. Selection of different radius of curvature are measured tip to the different crystal single crystal copper and silicon materials, and surface roughness profile parameters evaluat the test results obtained in different tip radii of curvature (tip wear different situations) for surface quality inspection of influence. At the same time, get the force curve experiments, research and force curves measured force-displacement curve, mutual transformation problem between the force distance curve. Transformed from the force-distance curves, get the tip first breakaway near the sample surface distance changes location, and get a different variation of the radius of curvature of the tip and the sample surface contact force.