Deformation of soft colloidal probes during AFM pull-off force measurements: elimination of nano-roughness effects

The forces needed to remove polystyrene (PS) and polyethylene (PE) particles from silicon wafers were measured using the atomic force microscopy colloidal probe technique. The polymeric probes had surfaces with nano-sized asperities. The ability to deform these asperities and conform to the topography of the substrate surface allowed the soft probes to mitigate roughness effects on the measured pull-off forces. Adequate deformations for surface asperities on PS and PE probes that resulted in reproducible probe-substrate contact area required loads of approx. 0.8-4 μN. For these applied loads the standard deviation in measured pull-off forces was reduced to 0.5-2.7%. © VSP 2005.