Surface Modification of AFM Si3N4 Probes for Adhesion/Friction Reduction and Imaging Improvement

Si 3 N 4 probes used for atomic force microscope exhibit large adhesion and friction resulting in artifacts of scanned image. In order to reduce adhesion and friction so as to reduce tip related artifacts, liquid lubricant (Z-TETRAOL) and fluorocarbon polymer (Fluorinert™) were applied on the Si3N4 probe. A comprehensive investigation of adhesion, friction, and wear of the uncoated/coated tips in both ambient air and various humidity levels as well as the influence of the coatings on the image resolution was performed. Experiments show that the coatings reduce the adhesion and friction of the Si3N4 tip, improve the initial image resolution, and exhibit less deterioration as compared to that of uncoated tip after scanning. The image degradation of an uncoated Si3N4 probe is also compared with that of an uncoated silicon probe. A probe cantilever deflection model was proposed to correlate the influence of the adhesion and friction with the image distortion.