The Structural and Electrical Properties of High-K Hf-Sm-O Thin Films Prepared by Atomic Layer Deposition

Thin film structures based on samarium and hafnium oxides films were prepared on silicon wafers by atomic layer deposition (ALD) from tetrakis(diethylamido)hafnium (IV) (Hf(N(C
2
H
5
)
2
)
4
, TDEAH), tris(isopropylcyclopentadienyl) samarium (III) (Sm(C
5
H
4
C
3
H
7
)
3
, Sm(
ⁱ
PrCp)
3
) and water as precursors. The films were examined with single-wave null ellipsometry, x-ray photoelectron spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM) and capacitance-voltage (CV) measurements. For Hf02 and Hf-rich films, the growth per cycle of 0.07-0.08 nm/cycle was obtained. The ALD process of Sm
2
O
3
and Sm-rich films when using H
2
O vapor as a co-reactant was shown to be significantly complicated due to a strong CVD-component. For the Hf-Sm-O films, only a phase of a disordered fluorite-like structure (space group Fm-3m) with a monotonic increase of the lattice parameter with the increase of Sm content was found. The films with dielectric constant value 20–25 were obtained at Sm concentration up to 17 at. %. The TEM studies revealed that the film consists of ~60 nm crystallites oriented to the normal of the surface.