ATMOSPHERE INFLUENCE ON IN-SITU ION-BEAM ANALYSIS OF THIN-FILM GROWTH

In-situ non-destructive surface characterization of thin film growth p rocesses in an environment of chemically active gas at pressures of se veral millitorrs is required both for the understanding of growth proc esses in multicomponent films and layered heterostructures and for the improvement of process reproducibility and device reliability. We hav e developed a differentially pumped pulsed ion beam surface analysis s ystem that includes ion scattering spectroscopy (ISS) and direct recoi l spectroscopy (DRS), coupled to an automated ion beam sputter deposit ion system, to study film growth processes in an environment of chemic ally active gas, such as required for the growth of oxide, nitride or diamond thin films. The influence of gas-phase scattering and gas-surf ace interactions on the ISS and DRS signal intensity and peak shape ha s been studied. From the intensity variation as a function of ambient gas pressure, we have calculated the mean free path and the scattering cross-section for several combinations of primary ion species and amb ient gas. Depending on the system geometry and the combination of prim ary beam and background gas, it is shown that surface-specific data ca n be obtained during thin film growth at pressures ranging up to sever al millitorrs. Detailed information such as surface composition, struc ture and film growth mechanism may be obtained in real time, making io n beam analysis an ideal non-destructive in-situ probe of thin film gr owth processes.