The post-annealing was carried out for the AuyNiCry
Ta films at 400 8C in Ar gas for 60 min. The critical
characteristic load of AuyNiCryTa films after annealing
is displayed in Fig. 7. There are no obvious changes
between Figs. 7 and 6. So it indicates that the critical
load of metallic films by scratch method was not
sensitive to post-heating process.
The critical load can be affected by the film thickness.
The Au film was fixed to different thickness by plating.
Fig. 8 shows the critical load as a function of the film
thickness of AuyNiCryTa and AuyNiCr films deposited
on Al2O3 substrate. The results show that the critical
load increases approximately linear with film thickness.
In general, if we assume that the adhesion is the same
and the critical load is determined by the extent of the
deformation, an increased film thickness requires an
increased indenting load to obtain the same deformation,
so that the critical load increases with the film thickness.
For metallic mulitilayers, when failure is produced
gradually, it is very difficult to determine the different
layer failure optically, so we concern the total failure.