G. I. Grigorov

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.

SYNTHESIS AND CHARACTERIZATION OF CONDUCTIVE TITANIUM MONOXIDE FILMS. DIFFUSION OF SILICON IN TITANIUM MONOXIDE FILMS

Abstract Titanium monoxide films of about 100 μm thickness have been deposited onto Si (100) by reactive ion beam deposition. The established experimental conditions provided reproducibility of synthesised films. With a fcc cubic structure and a lattice parameter of 4.17A, as found by X-ray diffraction ; this lattice value corresponded to an oxygen content of about 52%. The composition was confirmed by Auger electron spectroscopy based on the O-KLL\Ti-LMM integral ratio and on the observation of the fine features of the Ti-LMM peaks. The films were electrically conducting with a resistivity of 170 μΩ cm−1. The low diffusivity of Si in TiO films, as estimated by RBS analysis, offers potential application in microelectronics of the conductive oxide form.

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.

Apparent and real values of common gas sticking coefficients on titanium films and application to getter pump devices with periodic active film renovation

Abstract The getter pump design needs reliable values of the sticking coefficient of the pumped gas as well as their change during the getter film saturation. The paper deals with averaging of known experimental data for sticking coefficients of common gases on titanium films, taking into account their roughness. The kinetics of N 2 and H 2 sticking coefficients at different pressures is also given, which makes possible the design of getter pump devices with periodic active film renovation.

Theory of getter pump evaluation. Sticking coefficients of common gases on continuously deposited getter films

Abstract The principal points of a theory for the evaluation of vacuum devices with adsorbing walls, based on real values and distribution of molecular densities and sticking coefficients over the adsorbing surfaces, are discussed. A semi-empirical model for sorption on continuously deposited metal films is proposed. Relations for the dependences of sticking coefficients on temperature and sorption ratio for N 2 , CO, O 2 and H 2 sorption on Ti -films are given. Further practical aspects of getter pump evaluation and related problems of optimization as well as concrete examples are discussed.

Ion-induced densification of pvd films—a choice of the optimum density of ion bombardment

The densification process by ion-assisted physical vapour deposition of films is considered as a consequence of rearrangement of atoms in the near-surface film layer. A model is proposed allowing the quantitative estimate of the optimum ion current density required to produce a film with maximum density.

Optical properties of selective reflection TiNx films

Abstract The optical properties and the structure of thin titanium nitride substoichiometric and stoichiometric films were studied as a function of the conditions of film deposition. Optical constants of the non-transparent layers (thickness 2500 A) were determined by both dispersion analysis of the reflectance spectra and surface electromagnetic wave (SEW) phase spectroscopy methods. A new application of the selective reflection properties of the films in radiometry is suggested.

Quantitative Auger electron spectroscopic analysis of titanium nitrides

Abstract The analysis by Auger electron spectroscopy of the technologically important material TiN x by conventional methods (peak to peak heights in the derivative spectrum) is particularly delicate due to overlapping of NKLL and TiLMM peaks as well as to the chemical effect of the TiN bond on the peak shape TiL 3 M 23 V. Nevertheless quantitative analysis of TiN x is possible by using spectra acquired in the direct mode and measuring the area of the Auger signals. These areas are proportional to the number of the emitting atoms, whatever their chemical bonding may be. The method consists in normalization of the TiN x spectrum with respect to the Ti spectrum by equalization of the area of their peaks TiL 3 M 23 V, so we can estimate the total quantity of nitrogen (peak NKLL). Our method requires a calibration with only one titanium nitride sample of well known composition, besides a pure titanium sample.