Formation of {111} oriented domains during the sputtering epitaxy growth of (001) oriented Iridium films.

In the wafer-scale growth of Ir(001) on yttria-stabilized zirconia (YSZ)
by magnetron sputtering epitaxy two kinds of {111} oriented domains are observed.
One consists of sharp "fjord"-shaped features in which four 90° alternated rotational
variants of {111} are possible and the second one consists of islands with less defined
shapes in which eight 45° alternated rotational variants can be found. Their formation
occurs directly at the Ir/YSZ interface along incoherent grain boundaries, likely
nucleating at local defects of the YSZ surface. In order to avoid these misoriented
domains, process separation and proper etching pretreatment of the wafers both before
and between the sputtering processes have been found to be the key strategy for
achieving reproducibility and overall better material quality.