Molecular depth profiling using a C₆₀ cluster beam: The role of impact energy

Molecular depth profiling of organic overlayers was performed using a mass-selected C₆₀ ion beam in conjunction with time-of-flight (TOF-SIMS) mass spectrometry. The characteristics of sputter depth profiles acquired for a 300-nm Trehalose film on silicon were studied as a function of the kinetic impact energy of the projectile ions. The results are interpreted in terms of a simple model describing the balance between sputter erosion and ion-induced chemical damage. It is shown that the efficiency of the projectile to clean up the fragmentation debris produced by its own impact represents a key parameter governing the success of molecular depth profile analysis.