Molecular Depth Profiling using a C(60) Cluster Beam: the Role of Impact Energy.

Molecular depth profiling of organic overlayers was performed using a mass selected C(60) 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.