J.-P. Langeron

Aluminium diffusion in titanium nitride films. Efficiency of TiN barrier layers

Two kinds of reactively evaporated titanium nitride films with columnar (B0 films) and fine-grained (B+ films) film structures, respectively, have been examined as diffusion barriers for preventing aluminium diffusion. The aluminium diffusion profiles have been investigated by 2 MeV 4He+ Rutherford backscattering spectrometry (RBS) at temperatures up to 550° C. The diffusivity from 300° C to 550° C is: D[m2s−1]=3×10−18 exp[−30/(RT)] in B0 layers and D[m2s−1]=1.4×10−16 exp[−48/(RT)] in B+ TiN layers. The activation-energy values determined indicate a grain boundary diffusion mechanism. The difference between the diffusion values is determined implicitly by the microstructure of the layers. Thus, the porous B0 layers contain a considerable amount of oxygen absorbed in the intercolumnar voids and distributed throughout the film thickness. As found by AES depth profiling, this oxygen supply allows the formation of Al2O3 during annealing the latter preventing the subsequent diffusion of the aluminium atoms.

Diffusion of silicon in titanium nitride films. Efficiency of TiN barrier layers

Two kinds of reactively evaporated titanium nitride films with columnar (B0 films) and fine-grained film structure (B+ films) have been examined as diffusion barriers, preventing the silicon diffusion in silicon devices. The silicon diffusion profiles have been investigated by 2 MeV 4He+ Rutherford backscattering spectrometry (RBS) after annealing at temperatures up to 900° C, in view of application of high-temperature processes. The diffusivity from 400 to 900° C: D (m2 s−1)=2.5×10−18 exp[−31 kJ/mol/(RT)] in B0 layers and D (m2 s−1)=3×10−19 exp[−26 kJ/mol/(RT) in B+ TiN layers. The diffusivities determined correspond to grain boundary diffusion, the difference being due to the different microstructure. The very low diffusivity of silicon in B+ TiN layer makes it an excellent high-temperature barrier preventing silicon diffusion.

Iron diffusion from pure Fe substrate into TiN buffer layers

Abstract The diffusivity of iron in TiN films has been determined in samples prepared by reactive evaporation of Ti in N 2 atmosphere on silicon substrates followed by evaporation of pure iron. The iron diffusion profiles have been investigated by 2 MeV 4 He + Rutherford backscattering spectroscopy (RBS) after annealing at temperatures up to 600°C. The diffusivity from 200°C to 600°C, D [m 2 /s] = 1.4 × 10 −15 exp[−46/( RT )] is rather high when compared to the diffusivity of other atom species, as for example Si and Al, in TiN films.

Low temperature growth of highly oriented TiN films by ion-assisted deposition

Abstract Physical vapour deposition (PVD) at low temperatures leads to the formation of porous thin elemental or composite films. Dense films as well as single-crystal films can be formed, in general, by PVD at elevated temperatures of some hundred degrees Celsius. It has been shown experimentally that ion bombardment of a film during growth results in increased film density, as well as in decreased substrate temperature by epitaxial film growth. The results reported here, however, show that films of titanium nitride with high degree of orientation could be grown even at low temperatures by an appropriate low energy ion assistance of the growth process.

Formation of zirconia-ceria layers on silicon wafers using laser ablation

The effects of oxygen pressure and silicon substrate temperature on the formation of zirconia, ceria and ceria-stabilised zirconia layers have been studied by electron microscopy. The composition of the layers and the interaction at the oxide/silicon interface have been analysed using Auger electron spectroscopy, X-ray photoelectron spectroscopy and Rutherford backscattering spectroscopy. The conditions of the epitaxial growth of cerium-stabilised zirconia films produced by laser ablation have been found. A good matching of lattice parameters may allow the use of these oxides as buffer layers for high temperature superconductive film epitaxy on silicon wafers.

A simple estimate of deposited energy and concentration profiles in films produced by Ion-Assisted Physical Vapour Deposition

Analytical expressions for estimating the energy dissipation and the film constituent concentration profiles in films grown by Ion-Assisted Physical Vapour Deposition (IA PVD) are given. Two cases of IA PVD are considered: ion-assistance performed by inert-gas ions as well as by ions of a film constituent. As an example of application, concentration and damage depth profiles in h-BN films grown by IA PVD are calculated and a comparison is made with results obtained by computer simulation.

Silicon nitride films produced by ion-beam assisted deposition: bulk and near-surface composition

Experimental data on the nitrogen content in the films grown by ion-beam assisted deposition are compared to results given by an analytical estimate. The analytical expression used gives correct values for the film bulk nitrogen content and also describes the N concentration depth profiles.

Superstoichiometric h-BN films synthesized by ion-beam assisted deposition; N-concentration and respective ion energy dissipation

Abstract Experimental data on the nitrogen content in films grown by ion-assisted deposition are compared to the specific energy (per film atom) dissipated by the ions in displacement damage. As shown there exists a proportionality between the overstoichiometric N content and the energy dissipated in a superficial layer of the growing film.