Argon Ion Etching Research Articles

High Purity Chromium Metal Oxygen Distribution (Determined by XPS and EPMA)

The surface composition of ultra high purity chromium metal and chromium metal produced with conventional Cr +3 electrolyte was investigated via XPS. The distribution and formation of oxide in the matrix of chromium metal was also investigated via SEM. The results are discussed in terms of major elemental surface peaks for virgin material and after argon ion etching. It is demonstrated that the oxygen in ultra high purity chromium metal predominantly exists as a surface phenomenon in the form of Cr 2 O 3 and the thickness of the oxide layer is a function of the production method.

X‐ray photoelectron imaging of germanosilicate optical fibre preforms

AbstractThe germanosilicate glass core (GeO2–SiO2) of an optical fibre preform has been analysed and imaged using small‐spot (∼450 μm) x‐ray photoelectron spectroscopy (XPS). The germanium oxide was most readily detected in the glass preform sample using the Al Kα x‐ray‐induced Ge L3MM Auger feature. The observed Ge L3MM lineshape and estimated oxidation state shift of 8.8 eV with respect to pure germanium indicate that the germanium is predominantly in the form of GeO2 (+4 oxidation state) within the germanosilicate core. Argon ion etching was found to sputter preferentially the oxygen from the glass, and the observed changes in Ge L3MM Auger lineshapes suggest that suboxide defects (GeO) are produced. Quantitative XPS images and linescans were used to map the spatial distribution of germanium within the preform and were in good agreement with measured refractive index profiles.

X‐ray photoelectron spectroscopic study of ion etching and electrical biasing of silicon nitride on a carbon fiber

AbstractCarbon fibers with a chemical vapor‐deposited silicon nitride surface film have been investigated with core and valence band x‐ray photoelectron spectroscopy (XPS). The ability of the films to protect the fibers from oxidation was evaluated by heating, by argon and oxygen ion etching and by using an electrical biasing potential. Oxygen ion etching appears to oxidize the Si3N4 to SiO2, whereas argon etching removes the oxide and any hydrocarbon surface layer. The valence band data for Si3N4, Si2N2O, and SiO2 are interpreted by multiple scattered wave Xα calculations. The films crack when an electrical potential is applied, and the cracking is reproducible and irreversible, occurring particularly with a negative potential bias. We find chemical shifts on the core levels consistent with differential charging of the silicon nitride coating, an observation that is supported by sample biasing experiments. The work suggests that the cracking of the silicon nitride coating will significantly limit its effectiveness in protecting carbon fibers and carbon–carbon composites from oxidation.

Oxidation of TiN in an oxygen plasma asher

In previous work we have studied the thermal oxidation of titanium nitride. This involved temperatures of 350 °C and greater, and times of hours. In this work, we study the oxidation of titanium nitride in a downstream plasma asher, where the sample temperature is about 200 °C. For comparison to an older technology, we also include samples oxidized in a barrel asher where the sample temperature was about 100 °C. Oxidation times of 16 min and less were studied. Thickness and optical constants were measured using ellipsometry along with Auger electron spectroscopy with argon ion etching for depth profiles. The growth kinetics are shown to be logarithmic. In the down-stream asher, films form in 90 s which would require 40 min at 450 °C if grown thermally. We show that only the thinner films can be etched off in 50:1 HF.

The interaction of ethyl xanthate with copper(II)-activated zinc sulphide: Kinetic effects

Kinetic studies of ethyl xanthate adsorption onto copper(II)-activated zinc sulphide surfaces were performed by ultraviolet and Fourier transform infrared spectroscopy under flotation related conditions. Copper(II) activation is a prerequisite for ethyl xanthate adsorption on to zinc sulphide. Both the rate of adsorption and the form of the adsorbed ethyl xanthate species are controlled by the activation time and the concentration of copper(II) used. At low copper(II) additions, where copper(II) adsorption shows high affinity behaviour, copper(I) ethyl xanthate is the predominant surface species and the rate and extent of ethyl xanthate adsorption are decreased by extended copper(II) conditioning periods. At high copper(II) additions, where copper(II) is in excess, both diethyl dixanthogen and copper(I) ethyl xanthate can be detected on the zinc sulphide surface. However, their formation is by precipitation from solution rather than via a surface reaction. It is proposed that the penetration of copper ions into the zinc sulphide lattice and the subsequent diffusion back to the solid—aqueous solution interface may be responsible for the time dependence of ethyl xanthate adsorption. X-ray photoelectron spectroscopy depth-profiling by argon ion etching has confirmed that copper ions can penetrate considerable depths into the zinc sulphide lattice and gives credence to the proposed mechanism for the time-dependent adsorption behaviour of ethyl xanthate.

Ａｒイオン処理による塗工層構造の観察

It is suspected that there is a surface layer which structure is different from the inner part of the coated layer. And it might be easily considered that the structure of real cross section is broken when microtomed. The broken layer might cover the real cross section. The observation of the structure of the coated layer by a scanning electron microscope must be considered very carefully.Herein, we introduce a new technique to remove the above-mentioned layers in order to observe the inner or real structures.The technique includes argon ion etching procedure of the coated layer stained with osmium tetroxide. This etching is assumed to remove the layers resulting in clear observation of the structure.Using this technique, we can observe the coated layer structure more precisely. Application of this to two types of coated paper made in different drying temperature and to two kinds of coated paper of different air permeability shows effectiveness clearly and gives resonable results.

Tarnishing of Mo/Si multilayer x-ray mirrors

Multilayer x-ray mirrors of molybdenum and silicon operating at normal incidence at energies just below the Si L(II,III) absorption edges are a key component in the development of soft-x-ray projection lithography. In this application high reflectivity is essential. Aging tests on such reflectors, with Mo as the last layer deposited, show that the structures decline in reflectivity with time when stored in air. Chemical analysis of a well-aged surface by photoelectron spectroscopy techniques reveals that the uppermost Mo layer eventually becomes completely oxidized to MoO(3) and MoO(2) and contaminated with carbonaceous materials. The oxidation can be prevented by storing the mirrors in an oxygen-free atmosphere or by depositing the silicon as the top layer. The reflectivity of tarnished mirrors can be restored by removing the oxides by argon-ion etching or wet chemical methods.

Application of 252Cf plasma desorption mass spectrometry in dental research

Topically applied fluorides introduced in dental hygiene products elevate the concentration levels of fluoride in oral fluids and thus also affect chemical reactions of enamel de- and remineralisation. The chemical reactions on the surface of tooth enamel still are a subject of controversy. Here 252Cf-plasma desorption mass spectrometry and argon ion etching are used to analyse the molecular structure of the upper layes of enamel. The mass spectrum of untreated enamel is characterised by a series of cluster ions containing phosphate. It is evident that under certain conditions the molecular structure of the surface enamel is completely transformed by treatment with fluorides. The result of the degradation and precipitation processes is reflected by a total replacement of the phosphate by fluoride in the measured cluster ion distribution. Stepwise etching of the upper layers by Ar + ions reveals the transition from a nearly pure CaF 2 structure to the unchanged composition of the enamel mineral.

Photoemission study of porous silicon

We report x-ray photoelectron spectra from a porous silicon film (PSF) with a photoluminescence peak at 1.8 eV, as a function of argon ion etching time to probe the composition in the surface and the subsurface regions. The results clearly indicate that the surface layer is essentially a fluorine admixed SiO2 phase, while the Si:O:F composition of the subsurface region 2:1:0.2. With the possibility of the existence of hydrogen in this composition it appears that beyond the highly oxidized surface, PSF is a fluorine substituted siloxene derivative, which can be responsible for the visible photoluminescence.

Topography of sputtered Si(100) surfaces studied by STM in air

Investigations of the influence of Ar ion bombardment on the topography of Si(100) surfaces are presented. The dependence of surface roughness on the angle of incidence and ion dose has been studied. The samples, which were cut from commercially available wafers, have been prepared in a UHV system by argon ion etching at 3 keV primary energy. They have been exposed to air after preparation and have also been investigated by the STM in air. This ensured that the silicon samples were able to develop a native oxide layer just as in technological applications. A series of samples sputtered at normal incidence with different ion doses shows a maximum in surface roughness of 0.75 nm correlated to an ion dose of 240×10 15 ions/cm 2. A series, dependent on the angle of incidence, taken at an ion dose of 360×10 15 ions/cm 2 shows a maximum surface roughness of 1.2 nm at a sputtering angle of 60°C off surface normal. The results are in good agreement with theoretical calculations.

A Comparison of Argon and Hydrogen Ion Etching and Damage in the Si ‐ SiO2 System

We have etched films on Si with an Ar ion beam and a ion beam produced by a Kaufman ion source and at incident ion energies in the range of 300 to 1200 eV. Ion‐bombarded sample surfaces, maintained in high vacuum, were characterized by in situ spectroscopic ellipsometry (SE) over the photon energy range 2.0 to 5.5 eV and yielded the oxide thickness changes and damage depth produced by ion bombardment under various conditions of ion dose, ion energy, incidence angle, and substrate temperature. X‐ray photoelectron spectroscopy was used to confirm the SE results.

Certain features of the structure and properties of titanium carbide coatings on steels and cemented carbides

In recent years interest has increased in metal carbide and n#ride coatings, particularly of titanium carbide. Such coatings are used in industry for increasing the wear resistance of nonregrindable cutting tips of tungstencontaining cemented carbides and tool steel forming and measuring tools. At present in our country and abroad three methods of production of titanium carbide coatings are used: 1) the Sandvik Corromant (Sweden) method, CVD, for increasing the life of cutting tips and steel tools: 2) a method developed by Moscow Institute of Railroad Transportation Engineers in collaboration with Moscow Cemented Carbide Combine for increasing the life of cutting tips; 3) a domestic method, the basis of which was proposed in 1975 by N. A. Kulybaya and A. T. Reva, for increasing the life of steel tools. Despite the introduction into production of new and modern methods of plasma, ion-plasma, vacuum, and other methods of chemical deposition at high temperatures the CVD process continues to be successfully used in production. An analysis of the literature data shows that the properties of a titanium carbide coating may vary within very broad limits depending upon the method of application of it [1-3]. In this work titanium carbide coatings were applied using domestic methods 2 and 3 in a vacuum of 1.3.10-3-1.3" 10 -2 Pa in the presence of titanium sponge and titanium tetrachloride supplied to the working volume at 1000-1100°C. Specimens of carbon steels (0.2-1.2% C) and tungsten carbide-base cemented carbides (TT10K8B, TT7K12, VKS) were used as the base. The lattice parameter and orientation of the growth of titanium carbide were determined on a DRON-0.5 x-ray diffractometer in cobalt K s radiation. The lattice parameter was calculated from the centers of gravity of the diffraction peaks and the orientation of the titanium carbide growth from the results of comparison of the relative intensity of the diffractogram lines with theoretical data. The chemical composition of coatings on TT10K8B cemented carbide applied using methods 1 and 2 were also investigated. Formation of titanium carbide using the CVD-method occurs under conditions of continuous delivery through the muffle of a large quantity of hydrogen in a mixture with methane and titanium tetrachloride. In this case hydrogen is the carrier gas and the reducing gas of titanium tetrachloride. The investigation was made by the x-ray photoelectron spectroscopy method on a Zeibold Heraus LHS 10 spectrometer with use of aluminum K s radiation (h~ = 1486.6 eV) in a 3" 10 -9 Pa vacuum in combination with argon ion etching. The charge condition of the atoms was judged from the amount of the chemical shift of the spectral lines indicating a change in the energy of the bond of the electrons on the basic or outer electron levels. Titanium carbide was obtained using method 2 as the result of occurrence in the reaction volume of the following basic reaction:

Preparation and characterization of superhydrophobic FEP-Teflon surfaces

Abstraet-Supcrhydrophohic FEP-Teflon was prepared by argon ion etching followed by oxygen glow discharge treatment of commercially available FEP-Teflon sheet material. This combined treatment yielded an increase in water contact angle from 109° to > 140°. Ion etching alone caused a small increase in surface roughness and a loss of fluorine from the surface, but the water contact angles increased only to 120°. Scanning electron micrographs of ion-etched surfaces showed stalky protrusions with a diameter of approximatcly 40 nm. Glow discharge treatment of ion-etched surfaces reduced the length of these protrusions and therewith the microscopic surface roughness. However, in all cases the macroscopic surface roughness was less than 1 um (RA value). X-Ray photoelectron spectroscopy indicated major changes in elemental surface composition as a result of the treatments. These modifications did not influence the infrared absorption spectra (attenuated total reflection) of the modified surfaces, indicating that the chemical changes brought about are really superficial. It is concluded that the superhydrophobicity created is mainly due to changes in the specific, microscopic surface topography resulting from ion etching, but also partly due to the role of the glow discharge treatment, restoring a high surface concentration of fluorine after ion etching.

Characterization of electrochromic nickel oxide thin films prepared by anodic deposition

Nickel oxide (NiOx) thin films have been prepared on transparent conducting indium tin oxide (ITO) substrates by anodic deposition from a nickel ammine complex solution. Electrochromic (EC) behaviour of these films was observed in a borate buffer solution at pH 10 in the potential range 0–1 V vs. Ag/AgCl; an as-prepared film (PF) was cathodically reduced to a colourless form (RF) and oxidized to a brown form (OF) by anodic polarization. Characterization of these films by low-angle incident X-ray diffraction and X-ray photoelectron spectroscopy with argon-ion (Ar+) etching revealed that the EC properties are based on the electrolytic transformation of the NiOx structure between β-NiOOH and β-Ni(OH)2, i.e. involving the redox reaction Ni3++ e ⇄ Ni2+.

XPS studies of (Bi,Pb) 2Sr 2Ca 2Cu 3O y superconductors

We have systematically investigated the influence of Pb content on the grown of the high Tc phase in (Bi,Pb) 2Sr 2Ca 2Cu 3O y superconductors, and have determined the compositions and thermal conditions leading to compounds containing more than 95% of 110K phase by adding Pb of x=0.3. The electronic states of Cu, Bi and O atoms in compounds containing various volume fraction of 85K and 110K phases were examined by X-ray photoelectron spectroscopy (XPS). Effects of argon ion etching on the spectra showed that BiO bond strength was enhanced in the high Tc phase.

Oxygen ion etching of YBa 2Cu 3O 7− y

The oxygen ion etching rate ( R s) is investigated for the YBa 2Cu 3O 7 − y system. A higher etching rate is observed for oxygen than for argon ions. An increase of T c with etching is found. Furthermore, excess etching does not decrease T c below the T c value before oxygen etching, although argon ion etching decreases T c below 4.2 K. Thus, we conclude that oxygen ion etching is useful.

Coated silica as support for platinum catalyst I. Coating of silica with alumina, titania, and lanthana

Titania, lanthana, and alumina were coated on silica by the impregnation of silica with solutions of the corresponding salts, followed by drying and calcination. Threshold values for monolayer spreading of the three oxides were estimated by XRD and XPS, and the two methods gave consistent results. When a 2-dimensional close-packing model is used to calculate the amount of oxides needed to form a complete monolayer on the silica surface, the experimentally determined threshold coverage by titania is only about 30%, while alumina can cover up to 85% of the surface, and lanthana tends to be coated in excess of a monolayer. The results are discussed for each case. Though a decrease in surface area on coating was observed more or less in each case, the pore-size distribution pattern did not alter significantly, except in the case of lanthana coating, where a peak of large pores appeared. The distribution of the coating oxides throughout the pores of silica was practically uniform even with these simple coating methods, as verified by argon ion etching. Platinum deposition on the coated supports by impregnation was also uniform. Its electron binding energy is not significantly influenced by the monolayer coatings but appreciably lowered by lanthana coating.

X-Ray Photoelectron Spectroscopic Study of Cobalt(II) and Nickel(II) Sorbed on Hectorite and Montmorillonite

AbstractThe safe disposal of 60Co, 63Ni, and 59Ni has required considerable information on the interactions of Co2+ and Ni2+ with clay minerals in the geosphere. X-ray photoelectron spectroscopy (XPS) has been used to probe the sorption sites for Co2+ and Ni2+ on hectorite and montmorillonite. The spectra were measured for Co-hectorite, Ni-hectorite, and Ni-montmorillonite immediately following ion exchange and after washing the clay two and five times with distilled water. The spectra, recorded following etching of the surface with an argon ion beam, differentiate two sorption sites; a labile (to washing) fraction sorbed as ion pairs, and a non-labile fraction sorbed by ion exchange at broken bond and interlamellar sites. The data were consistent with the sorption of metal ions (Co2+, Ni2+) in a common “MO6” ligand environment.Co2+ had a greater affinity for exchange on hectorite than did Ni2+; but Ni2+ had a greater affinity for the surface of montmorillonite than for hectorite. The argon ion etching of Ni-montmorillonite gave rise to a new photopeak of 853 eV, which was probably due to elemental Ni formed consequent to the chemical violation of the surface by ion etching.

XPS examination of tin oxide on float glass surface

XPS analysis associated with argon ion etching was carried out on the underside of float glass to determine the oxidation states of tin. XPS spectra of pure Sn, SnO and SnO 2 specimens were measured at first. The binding energy of the Sn 3d 5/2 peak in these specimens in 485.03, 486.80 and 487.16 eV, respectively. A detailed scan for tin was made from 482 to 490 eV on the underside of a float glass sample, measured in the as-received state and after argon ion etching for 25, 45, 65 and 85 min. The asymmetry of the Sn 3d bands in all cases indicated the presence of several valences of tin on the float glass surface. Bands for three chemical states obtained from the data on Sn, SnO and SnO 2 were fitted to the spectra of the glass sample. The fit in all cases was excellent. On the basis of these excellent fits, it is thought that tin is present in the +4, +2 and 0 valence states. Based on changing ratios in the intensities of the three bands as a function of etching time, thus of depth below the original surface, the following conclusions were made: (1) Of the total tin content, Sn 4+ is the largest fraction. (2) Deeper into the glass, the fraction of Sn 4+ decreases gradually, while that of Sn 2+ and Sn 0 increases. (3) The total intensity of Sn 3d peak decreases with the etching depth.

Characteristics of II-VI semiconductor thin films grown by MBE on InSb substrates

Single and multiple layers of CdTe and CdMnTe have been grown by MBE on InSb substrates. Considerable attention has been given to the preparation of the substrate surface which was cleaned under vacuum using a series of argon ion etching and thermal annealing cycles, with progress being monitored by AES and RHEED. The subsequently deposited epilayers were grown, typically, at a rate of 0.5 mu m per hour. All undoped films studied so far have been found to be n-type with carrier concentrations in the range 1014-1015 cm-3, while layers doped with indium have exhibited a saturation in carrier concentration as the In atom concentration was increased, due to the generation of compensating acceptor states.