The erosion energy efficiency of sputtering

A new parameter of sputtering, the erosion energy efficiency, is defined as the ratio of the theoretical energy required to eject atoms to the experimental energy. This efficiency η (E) is shown to be proportional to the ratio of the sputtering yield Y(E) to the energy E and, even under optimum conditions never exceeds ～ 10%. The relationship of this efficiency to the broadening process occurring during sputter profiling resulting from recoil atomic motion and mixing is examined. It is shown that the ion energy conditions employed in both technological etching and sputter profiling systems are near optimum for energy utilization and profile broadening minimization.