AES Depth Profiling Research Articles

Self-controlled diffusion of Al in Cu thin film

A layer of copper with the thickness of 0.5 μm was sputter deposited on well polished aluminum substrates. The samples were exposed to a low pressure weakly ionized RF hydrogen plasma at different conditions. A layer of copper aluminide was formed on the sample at the temperature of approximately 250 °C. The formation of the aluminide was confirmed with the AES depth profile. The time necessary for formation of the coating depended on the sample temperature. At the maximum temperature of 250 °C it was three minutes, while at 320 °C it was 50 s. When the aluminum atoms reached the surface, the temperature of samples began to fall thus decreasing further diffusion of Al. This was explained in the terms of the change of the recombination coefficient for the reaction H + H → H 2. As the temperature of the samples fell as soon as the formation of the coating was accomplished, the possibility of self controlled formation of thin copper aluminide coatings is suggested.

AES, SIMS, XPS analysis and electrical conductance of Ta-doped SrTiO3 thin films

Abstract The doping process (homogenisation and chemical state of dopant) was studied in this work by SIMS and AES depth profiling. The conditions of Ta diffusion into the SrTiO 3 layer were selected (1100°C, 40 h). The conductivity measurement of the SrTiO 3 doped with different Ta concentration proved that the Ta is a donor type dopant. The chemical state of the Ta in SrTiO 3 was analysed by XPS and proved that the Ti 4+ is replaced by Ta 5+ in SrTiO 3 .

Depth profiling of an In0.53Ga0.47As/InP multilayer sample using grazing‐incidence sputtered neutral mass spectrometry with laser post‐ionization

Depth profiling of In0.53Ga0.47As thin layers in InP using sputtered neutral mass spectrometry with grazing-incidence ion beam sputtering and laser post-ionization was performed and compared with SIMS and AES depth profiling. The depth resolution was improved by using grazing incidence (at an incident angle of 77°) of a 10 keV Ar+ primary beam and was better than that in the AES measurement with 1 keV Ar+ bombardment at 70.3° and sample rotation. The distortion of the indium profile at the In0.53Ga0.47As/InP interface that was observed in the SIMS measurement with 2 keV O2+ bombardment at 81° was not observed in the grazing-incidence sputtered neutral mass spectrometry measurement. © 1998 John Wiley & Sons, Ltd.

Depth profiling of an In0.53Ga0.47As/InP multilayer sample using grazing-incidence sputtered neutral mass spectrometry with laser post-ionization

Depth profiling of In 0.53 Ga 0.47 As thin layers in InP using sputtered neutral mass spectrometry with grazing-incidence ion beam sputtering and laser post-ionization was performed and compared with SIMS and AES depth profiling. The depth resolution was improved by using grazing incidence (at an incident angle of 77°) of a 10 keV Ar + primary beam and was better than that in the AES measurement with 1 keV Ar + bombardment at 70.3° and sample rotation. The distortion of the indium profile at the In 0.53 Ga 0.47 As/InP interface that was observed in the SIMS measurement with 2 keV O 2 + bombardment at 81° was not observed in the grazing-incidence sputtered neutral mass spectrometry measurement.

Characterization of titanium hydride film after long‐term air interaction: SEM, ARXPS and AES depth profile studies

Characterization of titanium hydride film after long‐term air interaction: SEM, ARXPS and AES depth profile studies

The dependence of structural and mechanical properties on film thickness in sol-gel zirconia films

The structure, morphology, and mechanical properties of sol-gel zirconia films have been examined using XRD, AES depth profiling, AFM, and ultramicro indentation. There is a systematic variation in the structure and morphology of the zirconia films with increasing thickness. These changes include increases in the amount of monoclinic phase, substrate oxides, and a decrease in grain size. Ultramicro indentation measurements indicate measured hardness increases with film thickness. The highest hardness value was 6.12 GPa for a 900 nm thick film. However, these values may be influenced by the substrate oxide layer at the film/substrate interface which increases with film thickness. The modulus of the films appears to be thickness independent. As the films are made up of a number of separately fired layers, it appears that the property changes observed are also related to the number of thermal cycles experienced by the sample.

Sputtering‐induced surface roughness of polycrystalline Al films and its influence on AES depth profiles

Sputtering‐induced surface roughness of polycrystalline Al films and its influence on AES depth profiles

Organometallic chemical vapour deposition of cobalt/indium thin films using the single-molecule precursors [(CO) 4Co] aInR 3- a (R = CH 2CH 2CH 2NMe 2; a = 1–3)

Pure cobalt indium alloy thin films of the nominal compositions Co 0.50In 0.50, Co 0.66In 0.33 and Co 0.75In 0.25 were grown by OMCVD using volatile organometallic precursors of the general formula [( CO) 4 Co] a- InR 3-a [ R = CH 2 CH 2 CH 2 N( CH 3) 2; 1 : a = 1 ; 2 : a = 2 ; 3 : a = 3] . These organometallic compounds contain direct CoIn bonds and allow molecular control of the metal ratio of the grown films. The distribution of the metals were uniform throughout the films. The films were examined by AES depth profiling, SEM-EDX and X-ray diffraction. The phase composition of the films follows the phase diagram of the Co/In system, e.g. reflections of the crystalline phase Co, CoIn 2 and CoIn 3 were detected. Due to the multi-phase nature of the films, the coatings were unstable with respect to interfacial reactions with InP, e.g. the formation of CoP was observed by X-ray diffraction.

Plasma-deposited dielectrics for Cu metallization systems

The interaction of copper with PECVD silicon oxynitride films was investigated by different analytical and electrical methods. Using AES-depth profiling and RBS measurements, no copper diffusion in films investigated was observed after applying a thermal stress of 450°C for 1 h. However, copper migration was detected after applying thermal and electrical stress simultaneously (BTS). C-V and I-V measurements before and after different BTS-conditions were performed on MIS-structures with coppe dots. The shift of the C-V curves resulting from copper migration decreases with an increasing N/O-ratio of SiO x N y films, demonstrating the better barrier properties of silicon nitride compared to silicon oxide. Additionally, the time to failure (TTF) was studied as a function of thermal and electrical stresses. Again, SiN x -samples achieved the highest TTF-values. The polarity dependence of the leakage current suggests a Cu ion drift transport mechanism.

PECVD of silicon oxynitride for copper metallization systems

The interaction of copper with PECVD silicon oxynitride films were investigated by different analytical and electrical methods. Using AES-depth profiling and RBS measurements, no copper diffusion in films investigated was observed after applying a thermal stress of 450°C for 1 h. However, copper migration was detected after applying thermal and electrical stress simultaneously (BTS). C-V and I-V measurements before and after different BTS-conditions were performed on MIS-structures. Additionally, the time to breakdown was studied as a function of thermal and electrical stresses. From the resulting arrhenius plots the activation energies for the lowest electric fields applied were determined to be 1.85 eV for SiN and 1.3 eV for SiO. The polarity dependence of leakage current for both materials studied suggests a Cu ion drift transport mechanism. From all materials investigated, silicon nitride showed the best barrier behaviour against copper interaction.

Ellipsometric studies of polycrystalline molybdenum silicide thin films

Systematic ellipsometric studies of MoSi 2 (tetragonal) thin films formed by RTA processing of cosputtered Mo 25Si 75, Mo 30Si 70, and Mo 36Si 64 thin films are discussed. The optical properties of these films in the measured spectral range 1.3–5.3 eV were observed to be dominated by the microstructural variations such as due to the changes in density, oxide overlayer thickness and composition, surface roughness, and redistribution of available excess silicon (after formation of MoSi 2 (tetragonal) phase). These microstructural variations indicated modification of interfaces and significant change in conductivity, which were corroborated in the AES depth profiles and the electrical resistivity measurements.

MOCVD of Pb(Zr x Ti1-x )O3 thin films on MgTiO3/Si substrates and their electrical properties

Abstract Pb(Zh x , Ti1-x )O3(PZT) thin films were deposited on Si substrates using MgTiO3 as the buffer layer and the electrical properties of those MFIS structures were investigated. PZT and MgTiO3 films were made by MOCVD using ultrasonic spraying technique. Perovskite PZT films have been succesfully made at the substrate temperature of 550 to 600°C only when using MgTiO3 buffer layer. AES depth profile analysis and RBS analysis revealed that there is no remarkable interdiffusion and no formation of reaction layer between PZT and MgTiO3 and/or between MgTiO3 and Si substrate. The capacitance-voltage (C-V) curves of the MFIS structure which were made with PZT and MgTiO3buffer layer have shown the hysteresis resulted from the ferroelectric switching of the PZT films.

Study of the chemical bonding in tungsten carbide and chromium films by application of factor analysis on AES depth profiles

Factor analysis was used to deconvolve Auger spectra of tungsten carbides and chromium samples recorded during depth profiles of model samples. The various chemical states of the elements were clearly identified by this method. The different phases of tungsten carbides (α-WC, α-W 2C, β-WC 1−x) as well as the different oxidation states of chromium (Cr, Cr 2O 3, Cr x O y ) were separated. As the structure of these samples was well characterized by other techniques, the reliability of the factor analysis method could be examined by investigating the parameters which can influence the results of factor analysis. For both systems, the effect of the mathematical pretreatment of the spectra, like smoothing and differentiation on the number of factors detected was examined. For the tungsten carbide samples, the effect of the Ar + ion energy on the number of primary factors was also examined. In the chromium part of the study, the influence of the selected energy windows on the detected number of factors was studied. It has been shown that when taking care of the measuring conditions and the manipulation of the data, factor analysis offers great possibilities to study the chemical composition of samples.

AES Depth Profiles of Nitrogen Ion Implanted Austenitic Stainless Steel

AES Depth Profiles of Nitrogen Ion Implanted Austenitic Stainless Steel

オージェ電子分光法によるInP/GaInAsP多層膜の深さ方向分析

We have conducted Auger depth profiling analyses of InP/GaInAsP multilayer specimens, in which the surface roughness was caused by the argon ion sputtering. We have, then, carried out the quantitative evaluation of the surface roughness using the distribution of the each pixel height taken by an atomic force microscope. The obtained histograms of surface roughness were used to calculate the resolution function together with the functions of electron escape depth and atomic mixing (Hofmann's MRI model). We also compared the resulting resolution function with the one obtained by the depth profiles measured. In this convolution calculation, we have assumed that the atomic mixing layer thickness was 2 nm and the information depth was 0.75 nm. The resulting resolution function was in excellent agreement with the one obtained from Auger depth profile. Therefore, we conclude that the distribution of the height of each pixel taken by AFM corresponds to the functions of surface roughness of the depth resolution function on the AES depth profile with sample cooling method.

Surface and in-depth characterization of TiC/C and Ti(C,N) layers by means of AES and Factor Analysis.

Magnetron sputtered TiC/C multilayers and Plasma Vapour Deposited Ti(C,N) layers have been investigated by AES. The carbon sensivity factor has been calibrated for the correct composition of a TiC standard sample. Nitrogen has been measured indirectly based on the Ti(L3M23M23)/Ti(L3M23V) peak area ratio in the direct E.N(E) spectrum using Ti, TiC and TiN standard samples. The influence of Tougaard background removal has been tested. As the less accurate method taking the Ti peak-to-peak ratio has been found to give adequately good results. It has been possible to recalculate AES depth profiles, where only peak-to-peak values and no peak areas in the direct spectrum are available. Factor Analysis has been applied to AES depth profiling results. The data matrix in each column contains the linked experimental spectra of the measured elements. Based on the standard spectra the main components of a TiN layer on silicon have been identified by Factor Analysis. The structure of a TiC/C multilayer system has been resolved by the characteristic C(KLL) peak shape in C and TiC. Factor Analysis enables to calculate the individual profiles for Ti, TiC and C.

Development of Na+-sensitive membranes based on sputtered Na-Al-Si glasses

Na+-sensitive microdevices are of increasing interest for integration in microanalytical systems e.g. for biomedical applications or for industrial process control. In order to produce ultra thin Na+-sensitive layers with fixed and reproducible composition and, in particular, defined Na concentration by means of RF sputtering, an off-axis geometry of a magnetron with cylindrical target was chosen for minimizing back-sputtering effects from the already deposited material. With this inverted cylindrical magnetron (ICM) it was possible to obtain reproducible and controllable sodium aluminosilicate glass layers on semiconductor substrates. Several surface and thin layer analytical techniques were applied for characterization of the membranes and for stoichiometry control. Especially by the non-destructive nuclear reaction analysis method a constant Na profile throughout the glass layer and — together with AES depth profiles — the diffusion barrier effect of an Si3N4 interface layer could be verified. Electrochemical measurements proved Nernstian sensitivity down to 10−4 M Na+ in solutions of pH 7, supporting sufficient stability and reproducibility of the sputtered Na+-sensitive layers.

Spray deposited Tl-Ba-Ca-Cu-O films and bulks subjected to a common anneal

Superconducting TI-Ba-Ca-Cu-O (TBCCO) 2212 films have been prepared by annealing the spray deposited precursor Ba-Ca-Cu-O/MgO layers with crude TBCCO pellets. Properties of both films and bulks are described. To deposit the precursor films, an aerosol generated ultrasonically from aqueous nitrate solution was used. The prepared 2212 films were 23 mu m thick; the highest Tc=102 K was obtained in both film and pellet annealed at 850 degrees C for 30 min. The Jc values measured on some films were in the interval 103-104 A cm-2; the XRPD data show rather low grain orientation both in films and in bulks. The X-ray patterns revealed that the film samples contain more than 95 vol.% of 2212 phase; the bulks contain more than 90 vol.% of 2212. The AES depth profiles in the surface layers of films show a slight drop in the Tl content towards the film-substrate interface. From the Raman spectra, XRPD data, structural investigation and physical properties of obtained 2212 phases, correlations among cationic disorder, c axis parameters, Tc values and frequency of the Raman modes were deduced. Results of detailed thermogravimetric TG, DTG and DTA measurements of homogenized precursor Ba-Ca-Cu nitrate and oxide mixtures as well as those of the crude Tl-Ba-Ca-Cu oxide mixture are presented.

Combined EPMA and AES depth profiling of a multilayer Ti-Al-O-N coating

In order to compare thin-film electron probe microanalysis (EPMA) and Auger electron spectroscopy (AES) regarding reliability in quantifying chemical compositions of Ti-Al-O-N coatings with depth, a multilayer was prepared on a silicon wafer by using reactive ionized cluster beam deposition technique. Within a total thickness of about 25 nm the composition of the multilayer varied step by step from Ti-Al-O-N at the bottom to Al-O at the top. AES and, as an innovation, EPMA crater edge profiling was applied to measure the composition with depth. For quantification special thin-film EPMA techniques based on Monte Carlo simulations were applied. The chemical binding states of Al and Ti with depth were analysed using a high resolution energy analyser (MAC 3) for the AES investigations working in the direct mode. According to the deposition procedure the concentration profiles of the components varied with depth for both AES and EPMA measurements. AES provided a better depth resolution than EPMA. To get a true calibration of the depth scale an in-situ measurement method like an optical interferometry will be required. Assuming that the relative sensitivity factors are available AES depth profiling delivers concentration profiles with good accuracy. The new EPMA application provided quantitative depth profiles concerning concentration and coverage. For EPMA crater edge profiling the coating needs to be deposited on a foreign substrate because depth distributions of elements being present in both the layer and the substrate cannot be resolved. The combination of AES-depth profiling with EPMA crater edge profiling techniques is a powerful tool to analyse heterostructures quantitatively.

The Physicochemical Properties and Growth Mechanism of Oxide ( SiO2 − x F x ) by Liquid Phase Deposition with H 2 O Addition Only

Silicon oxide formation was studied by a novel liquid phase deposition (LPD) method with addition only at 35°C. The deposition rate could be controlled by varying the quantity of added. The LPD‐oxide was lightly oxygen‐deficient. FTIR spectra and AES depth profiles indicate that a small amount of fluorine was incorporated into the oxide. The composition of LPD‐oxide can be represented as . The physicochemical properties of LPD oxide were investigated, as was the behavior of fluorine in the oxide and the chemical reaction. A model for the LPD mechanism is proposed that satisfactorily explains all of the experimental phenomena observed.