Abstract: Atomic force microscopy (AFM) was used to investigate the nanofriction behavior of fluorocarbon films deposited on a single crystal Si substrate by surface technology systems' inductively coupled system (STS ICP). Thus the modification of the films with different thickness on the surface of the Si_3N_4 tip and its effect on the nanofriction behavior of the films were examined by scanning the original Si surface and the films using an original new tip or the film-modified tip. It was found that the films had much smaller friction forces than the Si substrate. The nanofriction behaviors of the films were closely related to the thickness, while they were liable to transfer onto the tip surface and hence to modify the tip surface during the scanning, which contributed to decrease the nanofriction and wear of the film.