AES Techniques Research Articles

Interaction of oxygen with palladium deposited on a thin alumina film

The interaction of oxygen with Pd particles, vapor deposited onto a thin alumina film grown on a NiAl(1 1 0) substrate, was studied by STM, AES, LEED, XPS, TPD and molecular beam techniques. The results show that O 2 exposure at 400–500 K strongly influences the oxide support. We suggest that the oxygen atoms formed by dissociation on the Pd surface can diffuse through the alumina film and react with the NiAl substrate underneath the Pd particles, thus increasing the thickness of the oxide film. The surface oxygen inhibits hydrogen adsorption, and readily reacts with CO at 300–500 K. For large and crystalline Pd particles, the system exhibits adsorption–desorption properties which are very similar to those of the Pd(1 1 1) single crystal surface. The molecular beam and TPD experiments reveal that, at low coverage, CO adsorbs slightly stronger on the smaller Pd particles, with an adsorption energy difference of ≈5–7 kJ mol −1 for 1 and 3–5 nm Pd particles studied.

Characterisation of the oxide scale on a Ti–2Al–2.5Zr alloy with and without pre-oxidation in an alkaline steam at 300°C

The oxide scales on a Ti–2Al–2.5Zr alloy with and without pre-oxidation oxidised at 300°C in an alkaline steam for approximately 13 000 h were studied by SEM, XRD, XPS and in situ AES techniques. Some of the samples were subjected to 400°C deionised water steam at a pressure of 10 MPa for 72 h for pre-oxidation. The result showed that the oxide scales on the Ti–2Al–2.5Zr alloy were composed of Al 2TiO 5 (TiO 2Al 2O 3), TiO 2, Ti 3O 5, Ti 2O 3, Al 2O 3 and TiO. A comparison study has been carried out between the pre-oxidised and without pre-oxidised Ti–2Al–2.5Zr to determine the influence of pre-oxidation upon the properties of oxidation resistance. The oxidation kinetics showed that the weight gains of the pre-oxidised samples were much less than that of the controlled samples, which was consistent with the results by in situ AES analysis. The AES results showed that the whole thickness of the pre-oxidised sample (approx. 33 000 Å) was thinner than that of the controlled one (approx. 40 000 Å), in contrast the pattern for the stable oxide scale was reversed, i.e. the pre-oxidised sample was much thicker. Thus pre-oxidation is an effective method to improve the oxidation resistance of Ti–2Al–2.5Zr.

Application of Auger Electron Spectroscopy and X-Ray Photoelectron Spectroscopy Analysis in Failure Analysis of Wafer Fabrication

In this study, field emission AES and small-area XPS techniques were used to analyze surface composition and depth profiles on discolored bondpads to identify possible root causes for nonstick failure. In wafer fabrication, the discolored bondpad problem was found in the fab process with hot Al alloy metallization, which had resulted in nonstick failure during the assembly bonding process. Analytical results indicated that discolored bondpads with nonstick failure might be due to TiN residue introduced during the bondpad opening etching process. The possible root cause of TiN residue on bondpads was then confirmed to be arisen from ARC (TiN) layer underetched during the bondpad opening etching process. The solution to eliminate TiN residue on bondpads was taken to increase the etch time at the bondpad opening fab process.

APPLICATION OF AUGER ELECTRON SPECTROSCOPY AND X-RAY PHOTOELECTRON SPECTROSCOPY ANALYSIS IN FAILURE ANALYSIS OF WAFER FABRICATION

In this study, field emission AES and small-area XPS techniques were used to analyze surface composition and depth profiles on discolored bondpads to identify possible root causes for nonstick failure. In wafer fabrication, the discolored bondpad problem was found in the fab process with hot Al alloy metallization, which had resulted in nonstick failure during the assembly bonding process. Analytical results indicated that discolored bondpads with nonstick failure might be due to TiN residue introduced during the bondpad opening etching process. The possible root cause of TiN residue on bondpads was then confirmed to be arisen from ARC (TiN) layer underetched during the bondpad opening etching process. The solution to eliminate TiN residue on bondpads was taken to increase the etch time at the bondpad opening fab process.

Chemical structure and interface reaction of LaCoO3/Si thin‐film system

AbstractAn LaCoO3 thin film was prepared on Si(111) substrate successfully using an amorphous heteronuclear complex, LaCo(DTPA)·6H2O, as a precursor. The surface chemical structures and interface reaction of LaCoO3/Si thin film were studied by XPS and AES techniques. The AES depth profile analysis indicated that the composition of the LaCoO3 thin film was relatively homogeneous with depth. Interface diffusion and chemical reaction took place at the interface between the LaCoO3 layer and the Si substrate during thermal treatment. The linear least‐squares fitting of the AES depth profile analysis indicated that the LaCoO3 decomposed into simple a oxide of La and Co at the interface. An SiO2 species also formed at the interface when the sample was treated at relatively high temperature. Interface diffusion and reaction were intensified with increasing calcination temperature and time. When the temperature was <650 °C, the interface species were mainly La2O3 and CoO simple oxides. After the temperature reached 700 °C, the interface species were La2O3, CoO and SiO2. Copyright © 2001 John Wiley & Sons, Ltd.

Correlation between the atomic and electronic structures in Dy/Mo(1 1 2) and Gd/Mo(1 1 2) adsystems

The atomic and electronic structures of Dy and Gd submonolayers adsorbed on the Mo(112) face have been investigated with the use of the LEED, EELS and AES techniques. The one-dimensional compression of the Dy films is accompanied by the appearance of a series of medium energy extra losses, whereas they are absent under analogous conditions for Gd. The effects indicate good correlation with the shape of the concentration dependences of the low energy loss for both adsorbates. The atomic and electronic structures of the Dy/Mo(112) and Gd/Mo(112) adsorption systems are compared and possible reasons for their correlation are discussed.

Surface studies of single-crystalline refractory metal low-dimensional structures

We present the results of surface investigations of novel heteroepitaxial metallic low-dimensional structures fabricated on the basis of high-quality single-crystalline refractory-metal films (W(100) with thickness of 30–2000Å on r-plane sapphire).Films were grown by laser ablation deposition technique. Procedure consisting of soft ion bombardment and annealing at 1200–1300K in UHV allowed to obtain atomically clean (100) film surface (without oxygen and carbon contamination) with four-fold symmetry LEED pattern typical for refractory metals. Study of atomic and electronic structures and composition of the film surface was performed by LEED, AES, and UPS techniques. UPS spectra of these low-dimensional metallic systems are presented and compared with electronic structure of bulk single crystals.

Corrosion behaviour of chromated Zn and Zn alloy electrodeposits

The influence of a chromate film on the corrosion behaviour of Zn, Zn–Co and ZnFe coatings was investigated. XPS, AES techniques were applied for characterisation of the iridescent chromate films, while the XRD method was used for the corrosion product analysis. Atmospheric field (4 years data), accelerated (neutral salt spray and SO 2 cabinet) tests and electrochemical measurements were applied for the corrosion resistance studies. The beneficial influence of alloying for chromated Zn electrodeposits was observed under the conditions, where Cl − ions were the dominant pollutant (marine test site, Cl − cabinet, Cl − aqueous solution). The degree of protection from the chromate film, in spite of their lower thickness, was detected to be higher for the alloyed samples. A higher concentration of Cr(VI) compounds in the passive chromate layers of alloyed samples may be the reason of their superior corrosion resistance.

The effect of pre-oxidation on the oxidation behaviour of Ti-alloy at 300°C in an alkaline steam

The oxide scales on Ti-alloy with and without pre-oxidation, oxidised at 300°C in an alkaline steam for approximately 13 000 h, were studied by SEM, XRD, XPS and in situ AES techniques. The result showed that the oxide scales on Ti-alloy were composed of Al 2TiO 5(TiO 2Al 2O 3), TiO 2, Ti 3O 5, Ti 2O 3, Al 2O 3 and TiO. A comparison study has been carried out between the Ti-alloy pre-oxidised and Ti-alloy without pre-oxidation, to determine the influence of pre-oxidation upon the properties of oxidation resistance. The oxidation kinetics showed that the weight gains of the pre-oxidised samples were much less than in the controlled samples. The results showed that the whole thickness of the pre-oxidised sample was thinner than that of the controlled one. In contrast, the pattern for the stable oxide scale was reversed, i.e. the pre-oxidised sample was much thicker. Thus pre-oxidation is an effective method to improve the oxidation resistance of Ti-alloys.

The reaction and poisoning mechanism of SO 2 and perovskite LaCoO 3 film model catalysts

The reaction and poisoning mechanism of SO 2 with LaCoO 3/Al 2O 3 film model catalyst have been investigated using AES, XPS and XRD techniques. Some sulfates such as La 2(SO 4) 3 were formed on the surface of the poisoned sample. SO 2 diffused into LaCoO 3 film and reacted with LaCoO 3 to form La 2(SO 4) 3, La 2(SO 3) 3, La 2O 2SO 4 and CoO species in the interior of the LaCoO 3 layer. The perovskite structure of LaCoO 3 was destroyed by invading of such sulfur and some new phases were formed, which led to the loss of the catalytic activity. The concentration of sulfur in the catalyst layer increased with the temperature and the time. After the sample was poisoned at a high temperature above 700°C or for a period of time longer than 9 h, the distribution of sulfur in the LaCoO 3 layer became homogeneous and the concentration was fairly low, suggesting that an equilibrium was achieved between the poisoning reaction and the decomposition of the sulfurous salts.

Atomic scale observation of iodine layer compression on Cu(1 1 1)

The atomic structure of the iodine covered Cu(1 1 1) surface was studied by STM in combination with LEED, AES and TDS techniques. It was established that iodine adsorption on Cu(1 1 1) leads to the uniaxial compression of chemisorbed iodine layer. The structure of the saturated iodine coverage on Cu(1 1 1) was described in terms of formation of the striped super heavy domain walls, with the interatomic distances in the wall being smaller than van der Waals diameter of iodine.

A comparison of radiation damage and mechanical and tribological properties of α-Fe exposed to intense pulsed electron and ion beams

Using RBS, SIMS, AES, TEM and SEM techniques, formation of different point and linear defects has been found in iron as a result of intense-pulsed ion beam (IPIB) treatment. The close correlation between the average scalar dislocation density with microhardness magnitude has been proved both in near-surface layers and at great depths. The comparable analysis of structure-phase damage after IPIB and intense-pulsed electron beam (IPEB) irradiation is interesting for an explanation of different modified properties and in industrial application of such treatments.

Oxidation Behaviour of PACVD-(Ti,Al)N Wear Resistance Layers

Sputtered (Ti,Al)N hard coatings are successfully used for dry high speed cutting. These films show a lower oxidation rate than TiN or TiC coatings. In our work (Ti,Al)N films were deposited on WC-6%Co substrates at a temperature of 490°C by plasma-assisted chemical vapour deposition (PACVD) using a gas mixture of TiCl 4 /AlCl 3 /N 2 /Ar/H 2 . Investigation of microstructure, crystalline structure and chemical composition was carried out using SEM, WDXS, TEM, AES and XRD techniques. The chemical composition of the deposited films showed a Al to Ti ratio of 1.33. The film thickness was 5.5 pm. Films showed a fine crystalline size, the metastable fcc crystal structure and a columnar growth. The film surface was under low compressive stress up to several 100 MPa. For (Ti,Al)N/WC-Co compounds the oxidation behaviour up to 1100°C (high temperature range) was studied. Therefore, samples were annealed or rapidly heated in air and under high vacuum condition using the laser shock method. The results show decomposition of the (Ti,Al)N structure to the TiN and the AlN phases at temperature values above 900 °C. Heating in air causes growing of a thin aluminum oxide layer at the film surface, which is a barrier for further oxygen diffusion to the alumina-film boundary. Additionally, at temperatures above 900°C oxidation of the WC-6%Co substrate surface was obtained in regions of opened cracks and film delamination.

Effects of Pt diffusion barrier layer on the interface reaction and electric properties of PZT film/Si(111) sample

AbstractThe effects of the Pt diffusion barrier layer on the interface diffusion and reaction, crystallization, dielectric and ferroelectric properties of the PZT/Si(111) sample have been studied using XPS, AES and XRD techniques. The results indicate that the Pt diffusion barrier layer between the PZT layer and the Si substrate prohibits the formation of TiCx, TiSix and SiO2 species in the PZT layer. The Pt barrier layer also completly interrupts the diffusion of Si from the Si substrate into the PZT layer and impedes the diffusion of oxygen from air to the Si substrate greatly. Although the Pt layer can not prevent completely the diffusion and reaction between oxygen and silicon, it can prevent the formation of a stable SiO2 interface layer on the interface of PZT/Si. The Pt layer reacts with silicon to form PtSix species on the interface of Pt/Si, which can intensify the chemical binding strength between the Pt layer and the Si substrate. To play a good role as a diffusion barrier layer, the Pt barrier layer must be not thinner than 140 nm. The existence of the Pt layer not only promotes the crystallization of PZT layer to form a perovskite phase but also improves dielectric and ferroelectric performances of the PZT layer.

Tribological studies of 1-alkyl-2,5-dithiohydrazodicarbonamides and their Mo–S complexes as EP and multifunctional additives

This communication reports a comparative study of the anti-wear, extreme pressure and friction reducing properties of 0.5% (w/v) admixtures of paraffin oil with 1-alkyl-2,5- dithiohydrazodicarbonamide ligands and their Mo–S complexes, i.e. μ-hydroxo-μ-(1-alkyl-2,5-dithiohydrazodicarbonamido)-bis-[dioxohydroxo molybdenum VI] using 12.7 mm diameter steel bearing balls in a four-ball test. In particular, the additive μ-hydroxo-μ-(1-n-butyl-2,5-dithiohydrazodicarbonamido)-bis-[dioxohydroxo molybdenum VI] exhibits an increase in the load carrying capacity of the lubricant and a decrease in the values of wear and coefficient of friction. The surface analysis of the wear-scar matrix of the used ball specimen has been investigated by SEM and AES techniques.

Self-organization of monolayer (Pb, Sn) adsorbates at Si(111) surface recoil-implanted by keV ion impact

The concentration changes of Pb and Sn at the Si(111)- 7 × 3 -(Pb, Sn) surface by 5 keV Ar + ion bombardment have been studied by means of XPS, AES and RBS techniques with LEED and STM techniques, in order to determine their cross-sections for desorption and recoil-implantation of them. The potential barrier heights for desorption and recoil-implantation of Pb at the Si(111)- 7 × 3 -(Pb, Sn) surface have been determined to be 1.4 ± 0.2 and 200 ± 140 eV, respectively, from the obtained cross-sections, while those of Sn to be 3.2 ± 0.7 and 4.7 ± 2.8 eV, respectively. These data are found to be very similar to those for Si(111)-1×1-Pb and Si(111)- 2 3 ×2 3 + 3 × 3 -Sn surfaces. The extremely high potential barrier heights for recoil-implantaiton of Pb are explained in terms of self-recovery of Pb atoms, which have been once recoil-implantated into the subsurface layers by the Ar + ion, to the original surface before the next Ar + ion comes again to the original surface. Co-existence of Sn atoms at the Si(111)- 7 × 3 -(Pb, Sn) surface is shown to shorten the characteristic time for the self-recovery of Pb, which is concluded to give an evidence for the self-organization.

Study of the electromigration behaviour of Au–Ag thin films deposited on SiO 2 substrate using AES, XPS and AFM techniques

The purpose of this work was to study surface diffusion of atoms in Au-Ag films deposited on SiO 2 substrate under the action of a d.c. field, focusing on the effect of chemical reaction at the Au-Ag/SiO 2 interface on the electromigration behaviour. Atomic force microscopy measurement depicted the time evolution of topography of Au-Ag film from uniformly distributed islands to a patch structure upon application of a d.c. current. This was accompanied by the binding energy shifts of Au 4f and Ag 3d photoelectrons due to surface charging during XPS analysis. Auger line scanning showed that the electromigration direction of Au atoms in Au-Ag film changed from being preferential towards the anode to the cathode when the substrate Si(111) was replaced by SiO 2 . However, the electromigration direction of Ag atoms in the same Au-Ag film was independent of the substrate. A possible chemical reaction at the interface between Au-Ag and SiO 2 substrate was observed by angle-dependent XPS analysis. The reacted Si product diffused to and segregated at the patch boundaries of the Au-Ag film, possibly forming the silicide AuSi x .

Study of the electromigration behaviour of Au–Ag thin films deposited on SiO2 substrate using AES, XPS and AFM techniques

Study of the electromigration behaviour of Au–Ag thin films deposited on SiO2 substrate using AES, XPS and AFM techniques

Study of the electromigration behaviour of Au-Ag thin films deposited on SiO2 substrate using AES, XPS and AFM techniques

Study of the electromigration behaviour of Au-Ag thin films deposited on SiO2 substrate using AES, XPS and AFM techniques

Adsorption of Ho on Mo(1 1 2) crystal face

Growth and atomic structure of Ho submonolayers deposited on the Mo(112) crystal face were investigated with the use of AES and LEED techniques. It is well known that various species of alkali metal, alkaline-earth and rare-earth adatoms adsorbed on the furrow faces form linear chain structures across the atomic rows of Mo(112) and W(112) surfaces. In contrast to this case Ho deposited on the Mo(112) face does not reveal an ordered structure in the annealed adlayers at low coverage. Upon further deposition of Ho, the adlayer undergoes one-dimensional compression in the 〈1̄11〉 direction and incommensurate (1×4) and (1×5) structures are formed. This behavior of Ho adlayers is similar to that of Gd adlayers adsorbed on the Mo(112) face and essentially different from that for Gd-, and Ho-W(112) adsystems. This fact is connected with the different nature of the indirect interaction between atoms adsorbed on Mo and W substrates at low coverages.