Yttrium iron garnet (YIG) film made as a magneto-optical medium suffers from
the problem of crack formation, caused by the heating process. YIG thin film
is deposited by radio frequency rf magnetron sputtering; the obtained layer
is amorphous and it needs annealing to be crystallized. After heat-treatment
at 740 ○C of the sample realized on quartz substrate, we observe cracks
on the entire film surface. This is due to the large difference between the
thermal expansion coefficient (5.5 ×10-7 K-1 for quartz and 10 ×
10-6 K-1 for YIG). In this paper we present a new fabrication
method to reduce this problem, we make a multilayer to obtain at the end a
uniformly unique layer with excellent crystalline structure. Such films have
the possibility to reach a thickness of 500 nm. YIG films have been studied
by Rutherford backscattering spectrometry (RBS), optic ellipsometry and the
scan electron microscope. The RBS spectra were collected in channelling
geometry with incident particles energy 2 MeV and 3.5 MeV. The thickness and
the stoichiometric value of the thin films have been evaluated. Simulation
of all spectra indicates a constant composition. Ellipsometry method is well
adapted to model the thin film structure layers, and to measure the
thickness of the film and the complex index of refraction. The theoretical
ellipsometric value of the index of refraction is (2.22) while the
experimental value is ranging from 2.2 to 2.3 for a wavelength of 1550 nm.