Contributions of backscattered ions to sputtering yields depending on primary ion energy

Sputtering yields for 33-150 keV protons normally incident on Cu-films deposited on different backing materials have been measured. The decrease of the Cu-film thickness was determined by Rutherford-backscattering. AS the used base materials have different backscattering intensities, the contribution to sputtering yield by incident ions and by the ions backscattered to the surface within the material could be separated. It was found that the relative contribution to-total sputtering yield by the backscattered ions increases slowly for protons in the energy range from 50 to 150 keV. For energies lower than 50 keV the sputtering yields are determined by the special geometry of the target sandwich used here.