Effect of cantilever deformation and tip-sample contact area on AFM nanoscratching

The present work investigates the effect of cantilever deformation and tip-sample contact area on the performance of atomic force microscopy (AFM)-based scratching tests. Nanoscratching tests are carried out using a pyramidal diamond tip on aluminum alloy surfaces. Three typical AFM cantilever deformation states are illustrated, and the actual normal loads applied on the surface of the sample are obtained using a new method. A theoretical model for AFM-based nanoscratching using a three-sided pyramidal tip is also established to calculate the effect of the tip-sample contact area for different scratching directions. The corresponding theoretical normal loads can be obtained with this model. Experimental and theoretical results are compared for the normal loads at an expected machined depth, with different scratching directions. The contact length between the chip and the rake face of the tip is found to be the key factor leading to an increase in the tip-sample contact area. This results in an actual normal load larger than the theoretical normal load at an expected depth, especially in the face-forward scratching direction. Similar variation in the normal load is observed in the edge-and sideface-forward scratching directions. The scratching direction has little effect on the depth of the scratched grooves. Comparing the actual normal load with the set normal load along different scratching directions reveals that the cantilever deformation in different scratching directions has little effect on the scratching process. VC 2013 American Vacuum Society.