SiNx overlayers have been grown on quartz and single-crystal Si substr
ates at room temperature by ablating a Si3N4 sintered target in a vacu
um environment and different gas atmospheres, N-2 and Ar. The film gro
wth was controlled by real time ellipsometry at a fixed photon-energy,
2.5 eV. Once the deposition process is completed, in situ spectro-ell
ipsometric measurements were obtained in the 1.5 to 5 eV photon-energy
range. The best curve fitting of the data is used to find the film co
mposition: a mixture of non-crystalline Si3N4, polycrystalline Si, p-S
i, and amorphous Si, alpha-Si. The film crystallinity is confirmed by
TEM. The volume fraction of the film components is determined from ell
ipsometry. The ellipsometric results are complemented by in situ chara
cterization of the film by XPS. The film stoichiometry was found to de
pend on the gas pressure. In fact, the ideal stoichiometry, x = 4/3, w
as achieved at a critical pressure, a value which depended on the kind
of gas used during deposition. (C) 1998 Elsevier Science B.V.