THE ULTIMATE DEPTH RESOLUTION IN SIMS PROFILING - LOW-ENERGY ION-BEAMMIXING OF AU-PT INTERFACE

The ion beam induced mixing of Au/Pt and Pt/Au multilayers in SIMS spu tter depth profiling with 2.5, 5 and 8 keV Ar+ and Xe+ ions has been s tudied. The depth resolution varies linearly as the square root of the bombarding energy and is slightly better for Xe+ than for Ar+ ions. T he decay lengths of the trailing edge are 12-30 angstrom in Pt and 30- 90 angstrom in Au. Experimental profiles are compared with simulations based on a model which describes the atomic transport from the initia l collisional phase to the late thermalized stage. Experimentally obse rved broadening is predicted by the model. The larger decay lengths in Au are attributed to more efficient electron-phonon coupling and thus more rapid quenching of thermal spikes in Pt than in Au.