Résumé
A charged particle entering matter interacts with both the surrounding atoms and electrons. A part or all of its energy is then transferred to the electrons or converted into displacement damage, depending on the kinetic energy of the particle. We report here observations of individual ion tracks on silica using atomic force microscopy. Swift heavy ion irradiation may create defects in SiO2 and bumps at the oxide/silicon interface. The appearance of the silicon bumps can be explained by the thermal spike model and corresponds to a drastic decrease of the effective oxide thickness. We also observed elongated and intermittent surface tracks after swift heavy-ion irradiation under grazing incidence. This result leads to the assumption that energy transfer itself along the incoming ion trajectory is discontinuous, in disagreement with the usual simplifying assumptions. Such AFM measurements have allowed an improvement in our understanding of the physics of interaction at the atomic scale.