Abstract: “Snap back” affects the cap
ability of the Atomic Force Microscope(AFM). On the basis of the Hamaker micro c
ontinuous medium theory, the adhesion mathematic model between the tip and the s
ample of the AFM is set up, which includes the repulsive force. The relationship
between the plastic force of the cantilever and the adhesion of the AFM is disc
ussed. The reason for the AFM “snap back” is discovered. By improving the rigi
dity of the cantilever, a method for avoiding “snap back” is put forward, foll
owed by the simulation result.

Key words: atomic force microscopy, snap back, Hamaker micro continuous principle