Evaluation of the depth resolutions of Auger electron spectroscopic, X-ray photoelectron spectroscopic and time-of-flight secondary-ion mass spectrometric sputter depth profiling techniques

Concentration-depth profiles of sputter-deposited Si/Al multilayered specimens were determined by model fitting to measured data obtained by depth profiling, using Auger electron spectroscopy (AES), X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary-ion mass spectrometry (TOF-SIMS). The model used for calculation of the concentration-depth profile accounts for the broadening (“smearing”) upon experimental depth profiling owing to the effects of atomic mixing, preferential sputtering, surface roughness and information depth of either the Auger electrons (for AES depth profiling) or the photoelectrons (for XPS depth profiling) or the secondary ions (for SIMS depth profiling). The depth resolution for each technique was derived directly from the values determined for the fitting parameters in the model.     

Investigation of interface properties of Ti/Ni/Ag thin films on Si substrate

The interface structure and the adhesion of direct current (DC) sputtered Ti/Ni/Ag thin film metallization on n⁺Si substrate has been investigated. It is shown that beside the chemical preparation of the Si surface prior to sputtering also thermal annealing of sputtered metal structure has strong influence on the adhesion of sputtered layers to the silicon. Energy dispersive X-ray spectroscopy (EDS) analysis were performed on both, the delaminated layers and on the silicon surface to determine the exact delaminating interface, which was found to be between Si and Ti layer. Auger electron spectroscopy (AES) profile revealed no traces of contamination at Ti-Si interface. Measured high tensile residual stress, particularly in sputtered Ni layer (1.4-2 GPa) is found to reduce the metal stack adhesion.     

动态离子束混合制备的钛氧化物薄膜的AES和XPS研究

分别采用O 和Ar 离子束轰击的动态离子束混合技术,在不锈钢基体上制备钛的氧化物薄膜。经X射线光电子能谱(XPS)和俄歇电子能谱(AES)分析,研究这两种工艺制备薄膜的化学组成和价键状态。结果表明,采用动态离子束混合技术制备的薄膜,可形成与基体有组分梯度的界面过渡层,减小了薄膜内应力,同时薄膜与基体具有较好的热学相容性,从而提高了薄膜的附着性能。Ar 束轰击的动态离子束混合沉积钛的氧化物薄膜中,Ti主要以 4价存在,而O 束轰击的动态离子束混合沉积形成的钛氧化物薄膜中含有次价态的钛氧化物。     

Correlation between electrical properties and AES concentration-depth profiles of NiCr thin films

Concentration-depth profiles of NiCr films about 1000 Å thick were determined by Auger electron spectroscopy (AES) combined with argon ion sputtering. Three different films on optically flat polished glass substrates were investigated: a Cr sublimation layer, an evaporated layer consisting of a Cr base layer and a top layer of Ni (of overall composition Ni:Cr 80:20 wt.%) and an evaporation layer produced from an NiCr 80:20 wt.% alloy. The sheet resistance, temperature coefficient of resistance and contact resistance were measured and are discussed in terms of the elemental distribution within the films.     

Refractory metal silicide formation by ion implantation

A systematic study of interface mixing of transition metal-Si structures by ion implantation was carried out. High resolution Auger analyses at the mixed region of the implanted samples showed an energy shift of the Auger Si LVV transition and a change in the spectrum relative to that of elemental silicon. The elemental depth distribution obtained using Auger electron spectroscopy combined with ion sputtering illustrated a composition plateau for the ion-implanted structures. The X-ray diffraction data show the presence of silicides. These results illustrated metal silicide formation and a reduction in the thermal reaction barrier for forming refractory metal silicides by ion implantation.     

Characterization of coatings

The variety of physical and chemical properties of coatings is determined by their thickness, structure and chemical composition. A fundamental understanding of coating properties, as well as of their reproducibility, therefore requires a good knowledge of these parameters.During the last few years great progress has been made in the field of chemical analysis (including depth distribution) of thin films and coatings. This progress is mainly the result of the combination of recently developed surface analytical techniques such as Auger electron spectroscopy (AES), photoelectron spectroscopy (UPS, XPS), ion scattering spectroscopy (ISS) and secondary ion mass spectroscopy (SIMS), on one hand, and controlled simultaneous surface etching by sputtering on the other.With these surface analytical techniques the chemical composition of the uppermost monolayers is detected by energy or mass analysis of ion- (ISS, SIMS), electron- (AES) or photon- (UPS, XPS) induced emission of ions (ISS, SIMS) or electron (AES, UPS, XPS), respectively. By combining these techniques with sputtering, the depth distribution of elements and compounds can also be determined with a lateral resolution of some microns.In order to recognize the capabilities and limitations of these techniques for coating analysis, the fundamental emission processes as they appear in the various analytical techniques, as well as the details of the sputtering process, have to be taken into account. The main features such as detection limits, isotope sensitivity, detection of compounds etc. of these techniques will be compared for some typical examples.Other methods, such as high energy ion backscattering and the detection of sputtered particles in the gas phase, will also be considered.     

The determination of surface composition profiles in glass by Auger electron spectroscopy and ion etching

Auger electron spectroscopy (AES) combined with ion etching was used to measure compositional profiles in the near-surface regions of glass. The profiles were obtained by making a linear series of analyses along the surface of a sloping ramp etched into the glass in a separate ion bombardment operation. Composition profiles obtained in this way from the topside and underside of production float glass are described and interpreted. The advantages of this alternative method of separate ramp etching over the conventional approach of fixed beam sputtering with anin situ ion gun are discussed.     

Microanalyses on the hydrogen permeated 70% SiCC films

SiCC films with content of 70% SiC were deposited by rf magnetron sputtering on stainless steel or NaCl substrate followed by argon ion bombardment. Samples were then submitted to hydrogen permeation at 3.23×10⁷ Pa and 500 K for 3 h. Secondary ion mass spectroscopy (SIMS) was used to analyze hydrogen concentration with depth and to check the formation of hydrogen related bonds in the SiCC films with IR measurement. Auger electron spectra (AES) and X-ray photoelectron spectra (XPS) were carried out to check the effects of hydrogen participation on shifts of chemical bonding states of C, Si and O contamination.     

Selected area and in-depth auger analysis of thin films

Auger electron spectroscopy (AES) has rapidly developed from a purely research oriented technique into an extremely versatile analytical method with unique features for qualitative and quantitative materials characterization. The low escape depth (5–10 Å) of the emitted Auger electrons makes it ideal for surface analysis and for depth profile impurity distribution analysis when combined with in situ ion sputtering.Both surface and depth profile analysis can be accomplished on a selected area by the use of optical or primary electron beam scanning techniques. Results are presented which illustrate the significance of the analytical capabilities of AES in the qualitative and quantitative analysis of thin film electronic materials used in the fabrication of precision thin film resistors, capacitors and conductors.     

The fabrication of metal silicide nanodot arrays using localized ion implantation

We propose a process for fabricating nanodot arrays with a pitch size of less than 25?nm. The process consists of localized ion implantation in a metal thin film on a Si wafer using a focused ion beam (FIB), followed by chemical etching. This process utilizes the etching resistivity changes of the ion beam irradiated region that result from metal silicide formation by ion implantation. To control the nanodot diameter, a threshold ion dose model is proposed using the Gaussian distribution of the ion beam intensities. The process is verified by fabricating nanodots with various diameters. The mechanism of etching resistivity is investigated via x-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES).     

Optimized depth resolution in ion-sputtered and lapped compositional profiles with Auger electron spectroscopy

Auger electron spectroscopy (AES) is usually used in conjunction with inert gas ion sputtering to obtain composition-depth profiles through surface layers. In certain cases the mechanical lapping of a taper through this region prior to analysis by AES is advantageous in terms of the depth resolution achieved. The regimes of preference of each technique are delineated by considering individually each of the terms contributing to interface degradation for the various types of layered structures encountered in practice, e.g. evaporated films and oxide layers. Illustrations of the effects of relevant parameters are given by measurements for a sharp deep interface between silver and iron.     

In-depth distribution of ion beam damage in SiC

In this paper we report on the ion beam bombardment-induced alteration of SiC measured at different ion energies (300-1700 eV) and at wide range of incident angle (43°-87°). Surface roughening was reduced by sample rotation during sputtering. The change of the concentration was characterized by Auger electron spectroscopy. Both low and high energy Auger peaks of Si were detected, which allowed us to estimate the depth distribution of the components. The observed alteration of Auger peak heights will be explained by simple model of the changed in-depth distribution. The model gives an estimate for the composition of top layer (the real surface) of SiC in different sputtering conditions, as well as the in-depth distribution of Si and C.     

Auger electron spectroscopy study of the sputtering effect on platinum silicide surfaces

Modifications of platinum silicides in the composition range between Pt₃Si and PtSi induced by argon ion beams were studied by angle-integrated Auger electron spectroscopy (AES). A platinum surface enrichment, which was stronger at low sputtering energies and in silicon-rich silicides, was found in the 1–5 keV ion energy range. In all silicides sputtering yield ratios Y_Si/Y_Pt of about 2.9 and 2.1 were estimated for the 1 keV and 5 keV steady state regimes respectively. Simultaneous analysis of low and high energy platinum and silicon Auger lines indicated that the platinum enrichment extended over a range of a few tens of ångströms and was slightly higher at the surface than in the subsurface region. The platinum enrichment, its energy dependence and the in-depth graded composition of the altered layer are discussed in terms of silicon preferential sputtering, recoil implantation and surface segregation. Dynamic surface composition changes were also studied, and a model which accounts for the various “shapes” of the transient regimes and their dependence on the height of the steps in the sputtering energy is shown schematically. Shape analysis of the core-valence-valence Auger lines suggests that changes in the chemical bonding in platinum silicides are induced by ion bombardment so that enrichment with platinum results in the formation of compounds which are richer in platinum.     

Influence of ion bombardment on depth resolution in Auger electron spectroscopy analysis of thin gold films on nickel

Thin film Auger electron analysis of gold films on nickel was performed while simultaneously sputtering with argon ions. The influence of film thickness, electron and ion beam energies, ion beam current density and initial surface roughness on depth resolution was investigated. The intrinsic limitations of depth resolution result from the escape depth of Auger electrons and from atomic mixing due to ion impact. Prolonged ion sputtering leads to the development of microroughness. The influence of this last effect is described by an empirical correlation which shows the width of the transition region to increase with the square root of the product of ion beam energy and film thickness. The original surface roughness also affects depth resolution but, at higher ion beam energies (2 keV) in particular, its influence is somewhat masked by ion-induced microroughness. Optimum resolution (5% of film thickness) in depth profiling is obtained by employing well-polished samples and low ion beam energies.     

BaTiO3/Si界面扩散与控制方法研究

利用激光分子束外延（LMBE）方法在Si（100）基片上直接生长BaTiO3（BTO）铁电薄膜。通过俄歇电子能谱（AES），X光电子能谱（XPS）等分析手段系统研究了在Si基片上直接生长BTO铁电薄膜过程中的界面扩散现象。根据研究得到的BTO／Si界面扩散规律，采用一种新型的“温度梯度调制生长方法”减小、抑制BTO／Si界面互扩散行为，实现了BTO铁电薄膜在Si基片上的选择性择优定向生长，为在Si基片上制备具有原子级平整度的择优单一取向的BTO铁电薄膜奠定了基础。     

表面成分AES和XPS定量分析中的离子溅射修正

低能离子溅射是表面分析中清洁固体表面和深度剖面分析的主要手段之一。由于离子溅射改变了固体表面化学成分，引起表面成分的再分布，使俄歇电子谱、X射线光电子谱以及二次离子质谱等表面分析手段，对溅射后固体表面成分的定量分析结果与实际结果有较大的差别。本文以离子溅射合金表面成分达到平行时择优溅射、离子轰击诱导偏析和增强扩散效应之间动态平衡状态的假设为基础，得到了一个与择优溅射、离子轰击诱导偏析和增强扩散修正因子有关的离子溅射修正因子的分析表达式，并将其应用于Ag－Pd合金的离子溅射定量修正计算，发现计算结果能够与实验结果较好地吻合。解释了合金离子溅射修正因子随离子参数的变化。     

9Cr18轴承钢表面不同等离子体浸没离子注入强化处理技术研究

采用不同的等离子体浸没离子注入(PⅢ)工艺在9Cr18轴承钢表面进行了气体、金属、金属加气体的离子注入和碳化钛(TiC)、类金刚石(DLC)薄膜的等离子体浸没离子注入与沉积(PⅢD).对处理后的试样进行了X射线光电子能谱(XPS)、X射线衍射(XRD)、俄歇电子能谱(AES)和拉曼光谱(Raman)分析;测试了处理前后试样的显微硬度、磨痕宽度和摩擦系数.结果表明:处理后试样表面均形成了不同的改性层,且改性层中化学组成和各元素的浓度-深度分布随处理工艺的不同而变化;处理后试样的显微硬度都有较大提高,最大增幅达77.7%;表面摩擦系数由0.8下降到0.16;磨痕宽度减少了23倍;与PⅢ工艺相比,相同参数下,PⅢD处理后的试样表面综合性能更加优异.     

Hg1-xCdxTe材料AES定量分析中的电子束和离子束效应

在Hg1-xCdxTe材料的AES分析中 ,由于分析电子束辐照作用 ,可诱导表面Hg原子的脱附和热升华 ,导致短时间内样品表面严重失Hg ,使AES定量分析结果产生很大的误差。实验结果表明 ,在超高真空中分析电子束辐照下局部Hg元素的挥发损失以负指数关系进行。通过选择离子束溅射速率大于电子束蒸发速率 ,并在溅射的同时进行俄歇信号收集 ,则可减小或消除分析电子束对元素Hg的蒸发作用 ,获得稳定的俄歇信号。实验结果还指出 ,溅射离子束的参数会影响元素的相对溅射产额 ,具体定量分析时应选择相同的溅射条件     

Author index

Glow discharge films with various ratios of carbon to tin were deposited on various metals and on glass. The ratio of carbon to tin was determined quantitatively by X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES). The AES data correlated well with the XPS data. The X-ray beam and electron impact effects on organo-tin films influence the composition and are discussed in detail. The ratio of carbon to tin was not constant throughout the glow discharge reactor and this inhomogeneity is accounted for by the prevalence of “atomic” polymerization rather than “molecular” polymerization. We demonstrated that the substrate material had a definite influence on the composition of the films.     

Er2O3／Si外延薄膜表面和界面组分研究

利用X射线光电子能谱方法对Si基Er2O3外延薄膜的化学组分进行了分析。在X射线照射样品和氩离子轰击使样品减薄的过程中没有诱发其他的化学反应。研究了清洁的Si和有氧化层的Si衬底上外延生长的Er2O3薄膜的表面和界面化学组分情况,并对上述两种不同的衬底上外延生长Er2O3薄膜的生长模式进行初步探讨。