MECHANISM OF ION-BEAM-INDUCED DEPOSITION OF GOLD

Ion beam induced deposition is a novel method of thin film growth in which adsorbed, metal-bearing molecules are decomposed by incident energetic ions thus leaving a deposit. In conjunction with finely focused ion beams this process is used in microelectronics for local repair, i.e., deposition of patches of metal film with better than 0.1 mum resolution. Each ion can decompose as many as 40-50 adsorbed molecules. The fundamental aspects of this process, namely how is the energy of the ion transferred to adsorbed molecules over a radius of up to 5 nm, have been studied. The decomposition yield (number of molecules decomposed/ion) was measured for Ne, Ar, Kr, and Xe ions at 50 and 100 keV. A model based on TRIM calculations was developed. The data correlate with this model confirming the view that collision cascades which can provide energy to surface atoms over a substantial area are responsible for ion beam induced deposition.