Preferred sputtering on binary alloy surfaces of the AlPdSi system

Auger spectroscopy has been used to investigate the behavior of preferred sputtering on surfaces of homogeneous AlPd, SiPd and AlSi alloy films. These combinations of alloys were chosen for studying the effects of mass and bonding differences on preferred sputtering. Experiments have been carried out using a 1 keV Ar ion beam over a range of alloy compositions. Our results can be summarized as follows: (a) The preferred sputtering of these binary alloys cannot be predicted according to the sputter yields of individual elements, e.g. both Al and Si have been observed to be removed preferentially relative to Pd although pure Pd has a higher sputter yield, (b) In the alloys studied, mass difference appears to dominate over bonding difference in controlling the preferred sputtering behavior since the extent of preferred sputtering of Al and Si relative to Pd is about the same. This observation is interpreted on the basis of the binary alloy sputtering theory formulated by Andersen and Sigmund. (c) Judging from the composition change of the sputtered surface, there is no evidence for formation of compounds with specific compositions as a result of preferred sputtering in the AlPd and SiPd alloys investigated.