On the variation of sputtering yield with angle of ion incidence

Abstract A geometrical theory is presented which divides the collision cascade into energy groups, each with a characteristic anisotropy in the distribution in space of knock-on trajectories. A simplified two group, four (quasi-two-dimensional) component analytical theory is developed. This is used to fit two experimentally determined sputtering yield versus angle of ion incidence relationships; 50 keV argon ion bombardment of gold and 100 keV argon ion bombardment of germanium. The experimental results were obtained using a triple quartz resonator technique. The effect of ion reflection on the measured sputtering yields was estimated by using the Monte Carlo computer simulation TRIM. A good fit to experimental results was obtained and it was demonstrated that models based solely on energy deposition combined with ion reflection are unsatisfactory for high energy (> 10 keV ) high mass (> 10 amu ) ions. The parameters determined from the fit of theory to experiment are used to determine the characteristic sputtering depths, and the mean ranges of the high and low energy groups for the two sets of experimental data.