Azimuthal Differential Sputter Yields of Molybdenum by Low Energy Xe+ Bombardment

Abstract

We present the development of a sputtering diagnostic based on a quartz crystal microbalance (QCM). The QCM system allows angularly resolved (differential) sputter yield measurements as a function of both polar angle and azimuthal angle. We discuss development of the QCM diagnostic and present sputtering data for molybdenum by xenon ions in the energy range 250-750 eV for bombardment at 0o, 30o, and 45o angles of incidence. Total sputter yields, found from integrating the differential sputtering profiles, are found to be in reasonable agreement with those in the literature. We fit the differential sputtering profiles with polynomials and theoretical expressions. For the energy range studied, we find under-cosine profiles for normally incident ions, and profiles dominated by forward scattering for the non-normally (obliquely) incident ions. Nomenclature y = differential sputtering yield (atoms/ion/steradian) Py = polynomial fit to differential sputtering yield (atoms/ion/steradian) Zy = theoretical fit to differential sputtering yield (atoms/ion/steradian) Y = total sputter yield (atoms/ion) YP = total sputter yield based on polynomial fit (atoms/ion) YZ = total sputter yield based on theoretical fit (atoms/ion) α = polar angle measured from surface normal β = ion incidence angle measured from surface normal φ = azimuthal angle in target plane measured from forward scattering direction