Self-organization during growth of ZrN/SiNx multilayers by epitaxial lateral overgrowth

Abstract

ZrN/SiNx nanoscale multilayers were deposited on ZrN seed layers grown on top of MgO(001) substrates by dc magnetron sputtering with a constant ZrN thickness of 40 Å and with an intended SiNx thickness of 2, 4, 6, 8, and 15 Å at a substrate temperature of 800 °C and 6 Å at 500 °C. The films were investigated by X-ray diffraction, high-resolution scanning transmission electron microscopy, and energy dispersive X-ray spectroscopy. The investigations show that the SiNx is amorphous and that the ZrN layers are crystalline. Growth of epitaxial cubic SiNx—known to take place on TiN(001)—on ZrN(001) is excluded to the monolayer resolution of this study. During the course of SiNx deposition, the material segregates to form surface precipitates in discontinuous layers for SiNx thicknesses ≤6 Å that coalesce into continuous layers for 8 and 15 Å thickness at 800 °C, and for 6 Å at 500 °C. The SiNx precipitates are aligned vertically. The ZrN layers in turn grow by epitaxial lateral overgrowth on the discontinuous SiNx in samples deposited at 800 °C with up to 6 Å thick SiNx layers. Effectively a self-organized nanostructure can be grown consisting of strings of 1–3 nm large SiNx precipitates along apparent column boundaries in the epitaxial ZrN.

First-principles quantum molecular dynamics study of TixZr1−xN(111)/SiNy heterostructures and comparison with experimental results

“…At these temperatures, the process of building SiN x ( α -Si 3 N 4 ) can be completed [26]. The evidence of this is the direct experimental results of XPS-analysis in figure 12.…”

“…a constant number of particles–volume–temperature) for ∼2.5 ps. In all of the QMD calculations, the time step was about 10 −15 s. The temperature (1130–1180 °C) was chosen from the experimental results obtained by the DSC (beginning of ZrN-phase crystallization) at substoichiometric α -Si 3 N 4 /MeN x (Me = metal, x < 1) [22, 26–29]. The system temperature was kept constant by rescaling the velocity.…”

Anomalous epitaxial stability of (001) interfaces in ZrN/SiNx multilayers

“…However, unlike TiN/SiN x structure 18 which grows with abrupt interfaces, nonhomogeneous distributions of dark regions interlaced in an overall cubic lattice, investigated as segregated SiN x precipitates, 19 are present here. No distinct SiN x layer sites can be marked in multilayers grown on MgO(111) substrate in the overview image in Figure 2(b).…”