Practical information and guidance
A new general, predictive semi-empirical equation for the sputtering yields of monoatomic elemental solids, using 250 eV to 10,000 eV ions incident normally on the surface, has been developed valid for Ne, Ar and Xe ions.
This equation is based on the approach of Matsunami et al. but includes a new atomic density term and avoids their arbitrary Q term. Matsunami et al.'s approach, although earlier, appears better than the more recent formulation of Yamamura and Tawara. Both of these approaches show significant scatter for the 34 elements analysed where Q had been assigned a value in the range 0.5 to 3 by fitting. In the new theory Seah, Clifford, Green and Gilmore and Seah, the Q values are re-determined for Ar, Ne and Xe ions only and are fitted with an equation involving tabulated physical data for the elements. This correlates with the experimental data at the 10% level showing a major improvement in accuracy for the above 34 elements as well as allowing extension to other elements where previously Q would have been set to unity. For these other elements, the yields may be up to a factor of 5 different from the value for Matsunami et al.'s approach. Data at 45° incidence are also given, calculated using the equations of Yamamura, Itikawa and Itoh.
For certain elements, including P, S, As, Sc, Sb, Te and Bi, there is a significant component of polyatomic sputtering that increases the sputtering yield by up to a factor of 5. This is explained in the paper by Seah, Clifford, Green and Gilmore.
For the convenience of analysts we show plots here for Ar, Ne or Xe at 0° or 45° incidence calculated using the data in the papers by Seah, Clifford, Green and Gilmore and by Seah. Tables of data are given below. Plots are also available as a function of Z or as a function of energy in the range 100 to 100000 eV. The data for Ne and Xe have been recalculated and revised from the plots first posted here on 27 May 2005 to correct a small calculational error found in implementing the above references. Small changes may be observed for all elements and, in particular, for Xe ions with low Z targets. In the plots, where data go beyond the top frame you will find the full curve on another plot in the set. The input data were for the range above 250 eV and low energy data are likely to have higher uncertainties. The predicted sputtering yields for most elements for Ne, Ar and Xe at 0° and 45° incidence angles are given in:
- Tables of values at 500 eV, 1keV, 2 keV, 5 keV and 10 keV energy
- 3 plots as a function of Z for the same energies as above at different expansions of the ordinate
- 6 plots as a function of energy, each for different small groups of elements
Input data of the element density, ρ, and energy of sublimation, Uo, per atom are given in the physical data table. If the element you are studying has a different density, ρ(1), and energy of sublimation, Uo(1), the sputtering yield Y(1) is given by
where Y is the value in the following tables.
The sputtering yields, Y, can be found in the following zip folder: Sputtering-yields