FRICTION EFFECTS IN THE DEFLECTION OF ATOMIC-FORCE MICROSCOPE CANTILEVERS

The conventional deflection-mode atomic force microscope operates by o ptically monitoring the slope near the end of a microcantilever in con tact with the sample surface. This signal is usually interpreted as a measure of height change. Lateral forces from friction, surface geomet ry, or inclination of the cantilever to the surface also affect the sl ope due to cantilever buckling. We calculate the deflection of a hollo w triangular model cantilever subject to both lateral and normal force s. The measured response of the servo circuit to an inclined, loaded c antilever is then determined. This shows (1) errors are always present in height measurements of structures on inhomogeneous surfaces; (2) t he sensitivity to buckling can be reduced by repositioning the laser; (3) friction measurements can be accurately made by scanning in two di rections and applying the proper calibration.