EELS characterization of TiN grown by the DC sputtering technique

Titanium nitride thin films were deposited on monocrystalline silicon (mc-Si) substrates by direct current reactive magnetron sputtering. Auger electron spectra (AES) of deposited films at different nitrogen partial pressures, show the typical N KL₂₃L₂₃ and Ti L₃M₂₃M₂₃ Auger transition overlapping. Also, changes in the Ti L₃M₂₃M₄₅ Auger transition peak are observed. X-ray diffraction and high resolution electron microscopy (HRTEM) of a golden color TiN/mc-Si sample, reveal a preferential polycrystalline columnar growth in the 〈111〉 orientation. This sample was also analyzed by electron energy-loss spectroscopy (EELS). The N/Ti elemental ratio is slightly different to the value determined by AES. Atomic distribution around the N atoms is in agreement with that expected from the N atom in the fcc unit cell of TiN. This distribution was obtained via an extended energy-loss fine structure (EXELFS) analysis from EELS spectra.     

Progress in instrumentation,data reduction,and depth profiles in Auger electron spectroscopy

Progress in the use of Auger electron spectroscopy is discussed. Specifically limits to spatial resolution in the scanning Auger microprobe resulting from backscattered electrons is illustrated. Determination of chemical state by peak shapes and energies are discussed along with the use of correction factors in quantitating Auger electron data. Finally, the use of inverse Laplace transforms of angle-resolved electron spectroscopy data to generate composition depth profiles of sputtered GaAs is illustrated. It is concluded that Gibbsian surface segregation during sputtering caused depletion of As near the surface of GaAs.     

Ta2O5/Ta界面分析的新模型

对Ta₂O₅/Ta样品界面区的深度剖面曲线进行了研究。基于离子溅射引起影响层存在的考虑,提出一种解释该曲线的新模型。通过此模型能很好地拟合实验曲线,并反映了溅射过程中的离子混合效应、原子堆积效应及相应的特征参数。样品由阳极氧化法制得,其厚度为500埃。表面分析在PHI-590型扫描俄歇微探针上完成,所有测量均在室温下进行。研究表明:深度剖面曲线并不符合误差函数分布;影响层的厚度为30—50埃,它是进行深度剖面分析时,决定元素俄歇信号强度的第一位重要因素;深度剖面 关键词：     

三元合金Cu76Ni15Sn9的离子溅射研究

在２７ｋｅＶ Ａｒ⁺离子轰击时,用收集膜技术结合俄歇谱仪（ＡＥＳ）,研究了三元合金Cu₇₆Ni₁₅Sn₉系统的择优溅射行为。同时使用扫描电子显微镜（ＳＥＭ）与电子探针微分析（ＥＰＭＡ）．观察了靶点表面形貌变化并测定了形貌特征微区的合金组份原子的相对百分浓度。结果表明,Ｃｕ原子较Ｎｉ原子、Ｎｉ原子较Ｓｎ原子,在所测定范围（０─６０°）内择优发射。最后讨论了靶点表面形貌特征和“元素局域富集”现象对择优溅射过程的影响。 关键词：     

Characteristics of sputtered Ta-B-N thin films as diffusion barriers between copper and silicon

Ta-B-N thin films were prepared by rf-magnetron sputtering from a TaB₂ target in N₂/Ar reactive gas mixtures and then used as diffusion barriers between Cu and Si substrates. In order to investigate the performance of Cu/Ta-B-N/Si contact systems, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), four-point probe measurement, scanning electron microscopy (SEM), cross-sectional transmission electron microscopy (XTEM), and Auger electron spectroscopy (AES) depth profile were used. Results of this study indicate that the barrier characteristics are significantly affected by the nitrogen content. In addition, the failure mechanism for the Cu/Ta-B-N/Si contact systems is also discussed herein.     

Investigation on surface compositions of CuNi alloy under Ar+ ion bombardment by ISS and in situ AES measurements

Surface compositions of CuNi(50 wt%) alloy under 3 keV Ar⁺ ion bombardment were measured by Auger electron spectroscopy (AES) and ion scattering spectroscopy (ISS). In situ AES measurement of sputter-deposited layer and sputtered sample surface indicated that surface composition became Ni-rich due to Ar⁺ ion sputtering at steady state, in accord with previous reports of preferential sputtering. ISS measurements with 3 keV Ar⁺ ions, however, have suggested that the composition of the outermost atom layer is not Ni-rich but slightly copperrich. This leads to the conclusion that the degree of preferential sputtering is small and that the question of preferential sputtering, particularly, the ratio of the sputtering yields, $\text{S}{}_{\mathrm{<mtext>Cu</mtext>}}\text{S}{}_{\mathrm{<mtext>Ni</mtext>}}$, based on AES measurement requires further examination.     

溅射相关的Pb97.4Sn2.6合金表面现象研究

本文对Pb_97.4Sn_2.6合金表面在溅射时所产生的一些现象进行了研究。实验在室温下,利用PHI-590型扫描俄歇微探针进行。根据理论计算结果对实验数据进行分析后,观察到了溅射增强扩散效应。当Ar⁺离子能量为5千电子伏,离子流密度为70微安/厘米²时,测得锡在合金中的扩散系数为10^-15厘米²/秒量级,影响层厚度约为200埃。 关键词：     

Effects of ion sputtering on semiconductor surfaces

Ion beam sputtering has been combined with Auger spectroscopy to study the effects of ion beams on semiconductor surfaces. Observations on the mass dependence of ion selective sputtering of two component systems are presented. The effects of ion implantation are explained in terms of atomic dilution. Experimental data are presented that illustrate the superposition of selective sputtering and implantation effects on the surface composition. Sample reduction from electron and ion beam interaction is illustrated. Apparent sample changes which one might observe from the effects of residual gas contamination and electric fields are also discussed.     

Reactive sputter deposition and metal–semiconductor transition of FeS films

FeS polycrystalline films were prepared on float glass by radio-frequency reactive sputtering. X-ray diffraction, scanning electron microscopy, Rutherford backscattering, and secondary ion mass spectroscopy were used to characterize the films. The effects of the deposition parameters, such as sputter power and substrate temperature, on the morphological structure and on the metal–semiconductor phase transition of FeS films were investigated. It has been found that the films show a substrate temperature dependent preferential orientation and phase-transition temperature. PACS 81.15.Cd; 68.55.Jk     

Dependence of Auger depth resolution and surface texturing on primary ion species

The dependence of Auger depth resolution and surface texturing on primary ion species was systematically investigated for polycrystalline Al, Mo, Ag and Ta films deposited on Si wafers, using 3 keV Ne⁺, Ar⁺ and Xe⁺ ions as projectiles. The resolution was found to depend strongly on ion species; the higher the ion mass, the better the resolution. The resolution improvement attained with Xe⁺ ions was dramatic for Al, becoming less pronounced for higher mass targets. As revealed by high-resolution scanning electron microscopy, Xe⁺ sputtering led to less-developed topographical structures of sputtered areas, which allowed us to conclude that ion sputtering with heavier ions roughens the surface less, resulting in a marked improvement in resolution.     

Effect of ion sputtering on the surface composition of tin-lead alloys

The surface compositions of two SnPb alloys (Sn_0.998Pb_0.002 and Sn_0.03Pb_0.97) were monitored by Auger electron spectroscopy during the relaxation that occurs after the cessation of argon ion sputtering. The data show that sputtering enriches the near surface region in Sn. It is concluded that, for this system, chemical bonding, i.e., the heat of vaporization, determines which component is enriched in the near surface region during sputtering.     

Ion sputtering rates of W-, Ti- and Cr-carbides studied at different Ar ion incidence angles

To study the ion sputtering rates of W-, Ti- and Cr-carbides, trilayer structures comprising C-graphite (59 nm)/WC (50 nm)/W (38 nm), C-graphite (56 nm)/TiC (40 nm)/Ti (34 nm) and C-graphite (46 nm)/C₃C₂ (60 nm)/Cr (69 nm) with a tolerance ±2% were sputter deposited onto smooth silicon substrates. Their precise structural and compositional characterization by transmission electron microscopy (TEM), Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS) revealed that the WC and Cr₃C₂ layers were amorphous, while the TiC layer had a polycrystalline structure. The ion sputtering rates of all three carbides, amorphous carbon and polycrystalline Cr, Ti and W layers were determined by means of Auger electron spectroscopy depth profiling as a function of the angle of incidence of two symmetrically inclined 1 keV Ar⁺ ion beams in the range between 22° and 82°. The sputtering rates were calculated from the known thicknesses of the layers and the sputtering times necessary to remove the individual layers. It was found that the sputtering rates of carbides, C-graphite and metals were strongly angle dependent. For the carbides in the range between 36° and 62° the highest ion sputtering rate was found for Cr₃C₂ and the lowest for TiC, while the values of the sputtering rates for WC were intermediate. The normalized sputtering yields calculated from the experimentally obtained data for all three carbides followed the trend of theoretical results obtained by calculation of the transport of ions in solids by the SRIM code. The sputtering yields are also presented in terms of atoms/ion. Our experimental data for two ion incidence angles of 22° and 49° and reported values of other authors for C-graphite and metals are mainly inside the estimated error of about ±20%. The influence of the ion-induced surface topography on the measured sputtering yields was estimated from the atomic force microscope (AFM) measurements at the intermediate points of the corresponding layers on the crater walls formed during depth profiling.     

A STUDY OF THE CRYSTALLIZATION OF AMORPHOUS Cu60Zr40 ALLOY

The crystallization of the amorphous Cu₆₀Zr₄₀ alloy has been studied by differential scanning calorimetry (DSC), scanning Auger microprobe (SAM) and transmission electron microscopy (TEM). The DSC trace showed that the sample exhibited a glass transition at 750 K and a strong exothermic effect beginning from 782 K. An enrichment of the element Zr and significant oxygen contamination in a zone near the surface to a depth of about 10 nm were revealed by SAM in the analysis of surface competition and depth profiles of the Cu₆₀Zr₄₀ sample. Also, the change of concentration ratio of Ca to Zr in amorphous matrix at the clean Cu₆₀Zr₄₀ surface as a function of annealing temperature was examined in detail, and it was found that the concentration of Zr at the surface is slightly higher than that in the bulk until 780K and that the concentration ratio of Cu to Zr in matrix has an abrupt increase in the temperature range of 780-800K. The observations by high resolution TEM revealed the appearance of cluster-like regions of approximately 1.5-2.0 nm in size just before crystallization and they distributed randomly throughout the sample. This phenomenon is analogous to the results obtained using field ion microscopy (FIM) by the present authors. The microstructural changes of the sample daring heating show the gradual crystallization of the amorphous matrix.     

Beobachtung von Elektronen-Channeling-Diagrammen im Augerelektronen-Spektrometer mit Rasterzusatz

In the scanning electron microscope the electron channeling patterns allow us to determine the orientation and quality of single crystal objects. If the Auger spectrometer is equipped with a scanning sample positioner, the electron channeling patterns can be observed with primary energies used in Auger spectroscopy, i.e. 0.5–5 keV.     

Evaluation of the barrier capability of Zr-Si films with different substrate temperature for Cu metallization

Barrier capability of Zr-Si diffusion barriers in Cu metallization has been investigated. Amorphous Zr-Si diffusion barriers were deposited on the Si substrates by RF reactive magnetron sputtering under various substrate temperatures. An increase in substrate temperature results in a slightly decreased deposition rate together with an increase in mass density. An increase in substrate temperature also results in grain growth as deduced from field emission scanning electron microscopy (FE-SEM) micrographs. X-ray diffraction (XRD) spectra and Auger electron spectroscopy (AES) depth profiles for Cu/Zr-Si(RT)/Si and Cu/Zr-Si(300 °C)/Si samples subjected to anneal at various temperatures show that the thermal stability was strongly correlated with the deposition temperature (consequently different density and chemical composition etc.) of the Zr-Si barrier layers. ZrSi(300 °C) with higher mass density make the Cu/Zr-Si(300 °C)/Si sample more stable. The appearance of Cu₃Si in the Cu/Zr-Si/Si sample is attributed to the failure mechanism which may be associated with the diffusion of Cu and Si via the grain boundaries of the Zr-Si barriers.     

Growth of textured nonstoichiometric MoTe2 films from Mo/Te layers and their use as precursor in the synthesis of MoTe2−xSx films

Molybdenum ditelluride, MoTe₂, thin films have been prepared on a glass substrate by depositing first a layer of Mo of 1 μm thickness by rf sputtering and then layers of tellurium of 4 μm thickness followed by annealing, in a vacuum sealed Pyrex tube, at 823 K for one hour. The films have been studied by X-ray diffraction, electron microprobe analysis, scanning electron microscopy and for optical and electrical properties. This indicated that the films so prepared are well crystallized and textured with a hexagonal structure similar to 2H-MoS₂. However, the film is non stoichiometric due to the presence of small amounts of oxygen. The optical properties are in good agreement with those of single crystals and film deposited by other means. The room temperature conductivity is of the same order of magnitude as that of single crystals. Finally, MoTe₂ has been used as a precursor for the growth of MoTe_2−xS_x films.     

Structural and optical properties of thin films of Cu(In,Ga)Se<Subscript>2</Subscript> semiconductor compounds

The chemical composition of Cu(In,Ga)Se₂ (CIGS) semiconductor compounds is analyzed by local x-ray spectral microanalysis and scanning Auger electron spectroscopy. X-ray diffraction analysis reveals a difference in the predominant orientation of CIGS films depending on the technological conditions under which they are grown. The chemical composition is found to have a strong effect on the shift in the self-absorption edge of CIGS compounds. It is shown that a change in the relative proportion of Ga and In in CIGS semiconducting compounds leads to a change in the band gap E_g for this material in the 1.05–1.72 eV spectral range at 4.2 K.     

High-resolution transmission and scanning electron microscopy of boride-nitride nanostructured films

The results of electron-microscopic studies of grain boundaries and the structure of fractures of titanium boride-and nitride-based films obtained by nonreactive magnetron sputtering are considered. The chemical and phase composition of the films is analyzed with the help of Auger electron spectroscopy and microscopic electron diffraction analysis. The structure of boundaries and the presence of amorphous inclusions, dislocations, and other structural distortions are discussed and the nature of the deformation under indentation is considered.     

SCANNING AUGER ELECTRON SPECTROSCOPIC INVESTIGATIONS OF MAGNETOSTRICTIVE NANOSCALE MULTILAYERS

The characterisation of thin magnetostrictive multilayers in the nanometerscale range [(4,5nmTb₄₀Fe₆₀/9nmFe)×100] demands a surface sensitive analytical technique. A suitable technique is scanning Auger Electron Spectroscopy (AES) to determine the elemental composition, the thickness, the presence of interdiffusion between thin layers, or the presence of contamination at interfaces.Auger sputter depth profiles are obtained by using Xe-Ion bombardment to etch the sample.Sample rotation during sputtering produces shallow craters, minimises roughening and enhances depth resolution. In addition, Auger maps of the craters are used to reveal the separated magnetostrictive Tb₄₀Fe₆₀ layers and soft magnetic Fe layers.     

Characteristics of biogenic calcite in the prismatic layer of a pearl oyster,Pinctada fucata

The fine structure of the calcite prism in the outer layer of a pearl oyster, Pinctada fucata, has been investigated using various electron beam techniques, in order to understand its characteristics and growth mechanism including the role of intracrystalline organic substances. As the calcite prismatic layer grows thicker, sinuous boundaries develop to divide the prism into a number of domains. The crystal misorientation between the adjacent domains is several to more than ten degrees. The component of the misorientation is mainly the rotation about the c-axis. There is no continuous organic membrane at the boundaries. Furthermore, the crystal orientation inside the domains changes gradually, as indicated by the electron back-scattered diffraction (EBSD) in a scanning electron microscope (SEM). Transmission electron microscopy (TEM) examination revealed that the domain consists of sub-grains of a few hundred nanometers divided by small-angle grain boundaries, which are probably the origin of the gradual change of the crystal orientation inside the domains. Spherular Fresnel contrasts were often observed at the small-angle grain boundaries, in defocused TEM images. Electron energy-loss spectroscopy (EELS) indicated the spherules are organic macromolecules, suggesting that incorporation of organic macromolecules during the crystal growth forms the sub-grain structure of the calcite prism.