Thin layers of the C60Fx molecules on the Si(1 1 1)-7 x 7 surface were investigated using scanning tunneling microscopy (STM) and high-resolution electron energy loss spectroscopy (HREELS). Experimental results indicate that the fluorine atoms can detach from C60Fx molecules and adsorb on the Si surface even at room temperature, which makes the surface chemically inert by formation of a strong Si-F bond. At the initial adsorption stage, the C60Fx molecules may release fluorine atoms either due to the rocking motion of trapped molecules or during their migration (rolling) on the Si surface. The diffusion of fluorine on the Si(1 1 1)-7 x 7 surface and the initiation of etching in the areas of the highest fluorine concentration at lower temperature (similar to 300 degreesC) than that for isolated fluorine sites, as well as coverage dependent step and terrace etching at higher temperatures, were also observed.