Depth Profiling Method Research Articles

Bone growth to metal implants is regulated by their surface chemical properties

Bony ingrowth to control (non-treated) and heat-treated stainless steel and Ti-6AI-4V implants into the medullary canal of the femur in rats was studied by mechanical, chemical and Auger electron spectroscopic methods. At all time intervals up to 35 d post-implantation, the shear strengths of the heat-treated Ti-6AI-4V and stainless steel implants were significantly higher (1.6-fold to 3.4-fold) than in control implants. Using Auger electron spectroscopy depth profiling methods, it was found that the heat treatment modified the implant surface composition significantly, resulting in a thicker oxide layer and other chemical changes. It is concluded that heat treatment of metal implants prior to their insertion alters their chemical surface properties and augments bony ingrowth to them.

Surface analysis of steel sheets with GDOS and EPMA

In the field of steel sheet characterization, chemical surface analysis plays a very important role. Surface composition effects the surface properties of the final product. At Voest-Alpine Stahl Linz the analysis techniques GDOS and EPMA are routinely used to characterize the steel sheet surface. Some fundamental experiments are here described for the optimization of GDOS depth resolution. In the documentation for a semiquantitative approach for steel sheet analysis, investigations and experience about minimum detection limits are presented. Self developed methods for concentration mapping and thickness mapping are described in the field of electron probe microanalysis; Also an EPMA depth profiling method is highlighted. Finally practical examples demonstrate the wide application range of the analysis methods.

High energy ERDA with very heavy ions using mass and energy dispersive spectrometry

The capabilities of the elastic recoil detection analysis (ERDA) method for depth profiling are investigated using high energy very heavy ion beams with energies close to the Coulomb barrier from the VICKSI accelerator and mass and energy dispersive recoil spectrometry by means of a time-of-flight energy detector telescope. Due to the unusually high beam energies of the 129Xe and 127I beams of 260 to 420 MeV, which nevertheless remain safely within the Coulomb scattering regime, the high velocities even of heavy recoil ions allow us their detection with unambiguous mass and adequate energy resolution for depth profiling up to depths of e.g. 3–4 μm in Si and 2 μm in GaAs. The concentration profiles of all target elements are measured simultaneously, uniquely resolved, since their isotopic masses are separated at least up to the Ga/As mass range. Typical depth resolutions obtained are comparable with values for RBS. The kinematical shifts between the separate depth profile spectra of the different isotopes of a probed atomic element clearly demonstrate that the depth resolution is reduced if only charges but no masses are resolved unless one isotope dominates.

Ion beam induced modifications of TiN and Ti films on Al-3% Mg substrates

Thin titanium nitride films (50–110 nm) deposited via magnetron sputtering on Al+3 wt.% Mg substrates were irradiated with Ar, Kr, and Xe ion beams at room temperature and with energies between 0.1–0.9 MeV. Sputtering yields and interface mixing rates were determined using Rutherford backscattering (RBS) as depth profiling method. The obtained TiN sputtering yields for Ar and Xe irradiation are found to be in good agreement with predictions of the Sigmund approach. A systematic study with Ar and Xe beams revealed a correlation of the mixing rate with the parameter d/Rp, where d denotes the layer thickness and Rp the mean projected ion range. The mixing data and Monte-Carlo calculations of the collision cascades elucidate the importance of focused recoil transport, especially in the case of Xe irradiations. The results from ion mixing experiments of titanium films (70–140 nm) on Al-3% Mg with 0.1–1.0 MeV Xe beams and 0.05–0.2 MeV Ar beams support these conclusions.

Proposed Methods for Depth Profiling of Residual Stresses using Beam-Limiting Masks

AbstractMethods are described which make use of x-ray absorbing masks to either limit beam penetration in the sample (Type I), or confine the diffracting volume within definite limits (Type II). The masks consist of a metal film of Au or U, containing many long, parallel apertures of effective width w and spacing c. The mask is either applied directly to the sample surface (Type I), or to a weakly absorbing film (Be or Kapton) on the sample surface (Type II). With the Type I mask, the diffracting volume can be limited to a surface layer whose maximum depth zm at ψ=0 varies linearly with w, irrespective of sample or wavelength. The masks can be used with ψ-tilts in an Ω-type goniometer, and strains and stresses can be determined by the Sin2ψ method. Depth profiles as a function of depth z (z-profiles) can be obtained with layer removal if gradients over the depth Zm can be neglected. With the Type n mask, the diffracting volume can be limited to a discrete subsurface layer whose average depth depends on (c+w) and the Bragg angle 2θ, and whose thickness depends on w and 2θ. z-Profiles can be obtained by varying the wavelength for a given reflection using a synchrotron source, without the need for layer removal. The methods have not yet been tested experimentally.

Proposed Methods for Depth Profiling of Residual Stresses using Grazing Incidence X-Ray Diffraction (GIXD)

AbstractTwo proposed methods are described for obtaining the depth profiles (τ-profiles) of strains and stresses as a function of the 1/e penetration depth τ, using GIXD in the asymmetric geometry, without the need for layer removal. In the first, the ψ-method: ψ is varied, for a given reflection, while holding τ constant, by varying the wavelength λ and adjusting the incident angle α so as to maintain τ constant. This allows dϕ,ψ vs Sin2ψ plots to be obtained at constant τ. In the second, the ϕ-integral method: interplanar spacings dϕ,ψ are measured for ϕ values from 0 to 2π, at constant ψ and τ by holding α fixed. Two ψ values, i.e. two wavelengths, are needed to obtain the whole strain tensor, but if the sample is quasi-isotropic and the stress state is biaxial, only one wavelength is needed. A direct method is also described for obtaining the profiles as a function of depth z (z-profiles) from the corresponding τ-profiles using inverse Laplace transforms. Application of the method to the residual strain vs τ data of Doerner and Brennan for an Al film on Si is presented.

Depth profiling methods that provide information complementary to neutron reflectivity

Neutron reflectometry (NR) has the potential to revolutionize our knowledge of the structure of polymers and other organic materials near surfaces and interfaces. The hydrogens of a polymeric species can be selectively replaced by deuterium so that the concentration versus depth profile of the deuterated species will result in a profile of neutron scattering length density of high contrast which, in turn, will strongly change the neutron reflectivity. Despite the excellent sensitivity of NR to rapid changes in the profile with depth, more gradual gradients in the depth profile can be almost invisible, and thus it is advantageous to pair NR with other experimental methods for depth profiling deuterium. Such methods allow one to place severe constraints on possible models of the scattering length density that can be refined to fit the reflectivity data. This paper reviews three such methods which recently have been developed for depth profiling hydrogen and deuterium in polymers, namely, forward recoil spectrometry, nuclear reaction analysis and dynamic secondary ion mass spectrometry. These methods have depth resolutions which range from 10 to 800 nm and can provide details of the profile not readily “visible” in reflectometry.

Improved method for depth profiling of multilayer structures

A modified, improved method has been developed for the dissolution of semiconductor materials containing a GaAlAs layer. This modified method involves the alternate application of anodic and cathodic processes in order to produce an arsenic-free surface for the carrier concentration measurement. The advantageous features of this method are demonstrated by comparison of the depth profiles of various semiconductor structures obtained by conventional and modified techniques.

Quantitative depth profiling with Fourier transform infrared spectroscopy

The quantitative nature of the variable-angle attenuated total reflectance (ATR) infrared depth profiling method has been explored in detail. Calculations are performed on model systems which support the use of the method under well defined conditions. The critical angle of internal reflection must be approached to provide a sufficiently large range in the depth of penetration. Absorption coefficients must be small enough to preserve the linearity in the Beer's law approximation to ATR. The method is applied to idealized polymeric systems in order to determine the limits of extractable information. It is found that simple and direct intensity normalization provides the general form of the concentration gradient of an analyte and is a useful aid in quantitative measurements. The conformational composition of poly(ethylene terephthalate) (PET) as a function of distance from the surface is studied. The method is used to examine conformational concentration gradients in PET that has been subjected to surface crystallization treatments.

Optimization of the depth resolution in elastic recoil detection

Elastic recoil detection (ERD) by 1H( 4He, 4He) 1H reaction is a fast, nondestructive method for depth profiling of hydrogen isotopes. The paper presents an experimental and theoretical study of the depth resolution under different conditions. A depth resolution of 10 nm can be achieved.

Depth Profiling of Oxidized Coal by Step-Scan Photoacoustic FT-IR Spectroscopy

Recently, we described results of preliminary step-scan photoacoustic (PA) infrared measurements that established the viability of the method for depth profiling of oxidized coal. We have continued these investigations, which involve monitoring the intensity of the ∼ 1750 cm−1 carbonyl band as the modulation frequency (and thus the thermal diffusion length) is varied, in order to determine whether the method is reliable and quantifiable. Some recent data that affirm this suggestion are presented in this communication.

Comparative bulk, surface and depth profile analyses on AlN and SiC-coated B4C powders

On thin layers of μm sized AIN particles, superficial enrichment of O, probably caused by atmospheric hydrolysis and/or oxidation, was detected by means of Auger Electron Spectroscopy (AES) combined with sputter depth profiling. By comparing the O/N ratio found at the surface with that of the bulk, determined by means of the carrier gas heat extraction (CGHE) method, surface enrichment appeared to be more pronounced for lower O coverages. Chemical speciation of O (H2O, CO2) was feasible using appropriate CGHE techniques. — Similarly, using AES and Secondary Ion Mass Spectrometry as depth profiling methods, surface enrichment of Si, C and O was found for two B4C powders, which had been coated by the sintering additive SiC. For this system, Laser Mass Microanalysis yielded additional information about chemical species. Combination of all applied methods led to comprehensive models of the natural and prepared particle coatings.

Improved and new surface analysis and depth profiling methods for the analysis of semiconductor technology problems : R. V. Criegern. Vacuum41(7–9), 1611 (1990)

Improved and new surface analysis and depth profiling methods for the analysis of semiconductor technology problems : R. V. Criegern. Vacuum41(7–9), 1611 (1990)

Study of Oxidation Properties of Amorphous Si:B Films

ABSTRACTThin films of an amorphous silicon-boron alloy with boron content 1–50 at.% have been deposited by low pressure chemical vapor deposition (LPCVD). The boron content and film thickness of the samples were controlled by regulating the ratio of diborane and silane gases during the deposition. It was observed that the crystallization of the amorphous alloy took place at higher temperatures as boron concentration was increased. After a thermal oxidation was performed, the stoichiometry of die resulting oxide layers on various samples was determined by the secondary ion mass spectrometry and Auger depth profile methods. While the threshold temperature for thermal oxidation was determined to be inversely proportional to the boron concentration, the oxidation rate showed a dramatic increase with boron content. In particular, an alloy containing 30% boron was readily oxidized at 500°C. Mechanisms for the enhancement of oxidation consistent with stoichiometric and spectroscopic properties of the oxide layers are discussed.

Ion beam mixing and sputtering of Kr-irradiated TiN films measured with RBS, RNRA, and PIXE

Thin titanium nitride films of 10–300 nm thickness were irradiated with 84Kr ions of 80–700 keV energy and fluences ranging from 1016 cm2 to 2×1017 cm2. Sputter yields (Y=0.4–1.0) and mixing rates (k=0.05–0.5 nm4) were determined using the depth profiling methods RBS, RNRA, and PIXE. While the sputter yields agree well with the modified Sigmund theory, the energy dependence of the mixing rates cannot be explained by standard models.

New nondestructive composition depth profiling method for diagnostics of multilayer quantum-well structures

A composition depth profiling method based on the measurement of the X-ray electron photoemission total yield is developed. When the X-ray photon energy exceeds the electron shell ionisation energies of the sample elements step-like increases of the total yield are observed. The magnitudes of the steps are related to the atomic concentrations; depth profiling is provided by scanning the angle of incidence of the X-rays. Examples of application of the method are presented.

Hydrogen in metallo-organic chemically vapor-deposited ZnS thin films determined by nuclear resonance reaction analysis

Nuclear resonance reaction analysis was used to determine hydrogen concentrationin polycrystalline metallo-organic chemically vapor-deposited ZnS films produced at low substrate temperatures and pressures. This method of hydrogen content determination is quantitative and non-destructive. Other available depth profile methods, such as secondary-ion mass spectroscopy (SIMS), are destructive and of limited quantitative use, as SIMS depends upon knowing accurate ionization yields for each type of matrix studied. Also, the nuclear resonance reaction analysis technique is not susceptible to vacuum artifacts associated with ion-sputtering techniques. Alteration of the H 2S-to-(CH 3) 2Zn flow rate ratio of reactants indicates that the hydrogen in the ZnS films is associated with the dimethylzinc, and not the hydrogen sulfide reactant. Variation in the substrate deposition temperature T s resulted in the decreased hydrogen concentration at increased T s (in the range 50–150°C). Hydrogen concentrations varied from about 1 × 10 20 to 2.0 × 10 21 atoms cm −3.

Improved and new surface analysis and depth profiling methods for the analysis of semiconductor technology problems

Following the ceaseless miniaturization of semiconductor circuits, the analytical techniques used to develop their technological processes must be continuously improved. This applies particularly to the lateral resolution, but also to new specific analytical needs, for example the sensitive detection of metal contamination on silicon surfaces. These two requirements have been selected here in order to point out some important recent advances in surface analytical techniques now available on a commercial basis for application to semiconductor technology problems.

The interaction of carbon tetrachloride with iron(110): a system of tribological importance

Quantitative adsorption studies, temperature-programmed desorption, Auger spectroscopy, and sputter depth profile methods have been used to study the interaction of CCl{sub 4} with Fe(110) at 90 and 300 K. Irreversible dissociative adsorption of CCL{sub 4} occurs at 300 K, and the only desorption product which is observed is the high-temperature iron chloride species. Auger spectroscopy shows that small coverages of chlorine remain on the surface of the crystal even after heating to > 1,070 K while the carbon diffuses into the bulk of the crystal at {approximately} 600 K. Correlations between the observed surface processes and tribology (the study of friction and wear) investigations are presented.

Analysis of multi-layered structures by a non-conventional Auger depth profiling method

In recent years, statistical methods of multivariate analysis have been successfully applied to Auger electron spectroscopy (AES). Factor Analysis (FA), for instance, has been applied both to provide chemical state information (not commonly obtainable by AES) and to improve the sensitivity of the technique. Up to now, however, in what concerns in-depth investigation, the application of FA was restricted to conventional depth profiling. In this work, FA was applied to Auger Crater Edge Profiling of multi-layered structures. Taking a PdPd 2SiaSi:H system for example, an improvement by a factor 2 in relative depth resolution in comparison to the conventional method was obtained. Apart from this, chemical state information was obtained, especially at the interface regions. The method was also applied to other structures, providing similar results.