Nondestructive surface analysis by nuclear scattering techniques

An elastic-recoil detection (ERD) technique is developed and successfully applied in the simultaneous, nondestructive multielement depth-profile studies of thin films with thicknesses up to 2 μm, used in various material technologies. In this technique, the light elements are knocked out of the target by using an energetic heavy ion beam obtained from the Tandem Accelerator Facility of the Nuclear Physics Laboratory. A time-of-flight method is used to separate the masses and the energies of the recoiled elements as well as the Rutherford backscattering incident ions. Using 30 MeV 35Cl as the beam probe, we get an observed surface resolution of better than 100 A at a 30 degree detection angle. Typical mass resolutions for energies > 5 MeV are 0.2 amu in the C region and 0.7 amu in the Si region. The factors related to the mass and depth resolutions, probing depth, and approximate detection limit are systematically studied using 19F, 35Cl, and 79Br as incident beams. This newly developed ERD method, along with the existing Rutherford backscattering (RBS) technique, makes the Nuclear Scattering Facility at the Universite de Montreal unique for surface analysis. (14 refs., 3 tabs., 6 figs.)