Ion Beam Thinning Research Articles

Coupled Si–Al Biogeochemistry: Occurrence of Aluminum in Diatom‐Derived Biogenic Silica

AbstractDiatoms play an important role in the biogeochemical cycling of aluminum (Al) in oceans. This occurs via the uptake of biological Al (Albio), which is incorporated into the structure of diatom‐derived biogenic silica (DBSi) and the formation of adsorbed Al (Alads) on the DBSi surface of post‐mortem diatoms. Al occurrence influences DBSi dissolution and thus diatom‐driven carbon sequestration. However, the mechanism of Al occurrence in DBSi remains unclear. In this study, Albio and Alads of DBSi from various diatom fossils in marine diatomaceous sediments were identified and quantified by combined focused ion beam thinning, elemental analysis, and the Al K‐edge X‐ray absorption near edge structure. Results showed the coexistence of Albio and Alads in all diatomaceous sediments and Al‐bearing DBSi thus constitutes a biological Al pool. Albio and Alads were mainly fourfold‐ and sixfold‐coordinated, respectively and Alads was much more abundant than Albio. Moreover, even at low concentrations (with an Al/Si atomic ratio of 0.0031), Albio can inhibit DBSi dissolution, effectively decreasing the extent of DBSi dissolution by ∼14%. Albio also significantly increased the mechanical strength of DBSi. The average Young's modulus (a measure of the stiffness of a material) of cribrum layers in Al‐incorporated DBSi was ∼1.4 times higher than that of Al‐free DBSi. Our results further demonstrate that diatoms play a dominant role in the biogeochemical cycling of Al in oceans, and the Al of DBSi participates in diatom‐driven Si and C coupled cycles in oceans, influencing the effectiveness of diatom‐driven carbon export by regulating the dissolution and mechanical strength of DBSi.

Efficient removal of Cd2+ by diatom frustules self-modified in situ with intercellular organic components

The organic modification of three-dimensional porous diatom frustules (biosilica) and their fossils (diatomite) is promising in heavy metal adsorption. However, the preparation of such materials involves complex processes, high costs, and environmental hazards. In this study, organic-biosilica composites based on in situ self-modification of diatoms were prepared by freeze-drying pretreatment. Freeze-drying resulted in the release of the intercellular organic components of diatoms, followed by loading on the surface of their diatom frustules. The bio-adsorbent exhibits outstanding Cd2+ adsorption capacity (up to 220.3 mg/g). The adsorption isotherms fitted the Langmuir model and the maximum adsorption capacity was 4 times greater than that of diatom biosilica (54.1 mg/g). The adsorption kinetics of Cd2+ was adequately described by a pseudo-second-order model and reached equilibrium within 30 min. By combining focused ion beam thinning with transmission electron microscopy–energy dispersive X-ray spectroscopy, the internal structure of the composite and the Cd2+ distribution were investigated. The results showed that the organic matter of the composite adsorbed approximately 10 times more Cd2+ than inorganic biosilica. The adsorption mechanism was dominated by complexation between the abundant organic functional groups (amide, carboxyl, and amino groups) on the surfaces of composite and Cd2+. The bio-adsorbent was demonstrated to have wide applicability in the presence of competitive cations (Na+, K+, Ca2+, and Mg2+) and under a wide range of pH (3–10) conditions. Thus, the self-modification of diatoms offers a promising organic–inorganic composite for heavy metal remediation.

Nitrogen ion beam thinning of a-SiCN diaphragm for environmental cell prepared by low-energy ion beam enhanced chemical vapor deposition

An amorphous silicon carbonitride (a-SiCN) diaphragm for environmental cell transmission electron microscopy (E-TEM) was fabricated by ion-beam-induced chemical vapor deposition (LEIBICVD) with Ar+ ions accelerated by 1.5 kV and hexamethyldisilazane (HMDSN). The diaphragms were applied to a KBr substrate or a Cu grid with 100-μm-diameter holes. Then, the deposited film was irradiated by N+ ions accelerated at 1.5 kV for thinning and nitriding. Optical microscopy revealed that the diaphragm deflection decreased with increasing N+ ion dose. These films, which were observed by E-TEM, were amorphous and transparent to an electron beam accelerated to 300 kV and caused no charging. Fourier transform infrared spectra and X-ray photoelectron spectra revealed that higher N+ ion doses helped to eliminate organic compounds and hydrogen, and promoted the formation of Si–N and C–N bonds in diaphragms. A diaphragm with a 15 nm film thickness after etching by N+ ion irradiation was successfully developed that could resist a differential pressure of 0.3 MPa.

Ga-contamination-free scanning transmission electron microscope sample preparation by rectangular-shaped oxygen-ion-beam thinning using projection ion beam optical system

Rectangular-shaped oxygen O2+ ion beam thinning for scanning transmission electron microscope (STEM) sample preparation was investigated using a projection ion beam optical system equipped with a duoplasmatron gas ion source. The ion current can be increased by increasing the area of the rectangular-shaped oxygen ion beam and thereby overcome the low brightness of the ion source. Rectangular-shaped O2+ ion beams with different amounts of projection beam edge blur were formed in the X and Y directions by using a limiting mask between the ion source and projection mask. Gallium-contamination-free STEM sample preparation (rough, medium, and fine milling) was demonstrated using a projection ion beam optical system and three types of rectangular-shaped oxygen ion beams.

Cross-shaped markers for the preparation of site-specific transmission electron microscopy lamellae using focused ion beam techniques

We describe the use of a cross-shaped platinum marker deposited using electron-beam-induced deposition (EBID) in a focused ion beam – scanning electron microscope (FIB-SEM) system to facilitate site-specific preparation of a TEM foil containing a trench defect in an InGaN/GaN multiple quantum well structure. The defect feature is less than 100 nm wide at the surface. The marker is deposited prior to the deposition of a protective platinum strap (also by EBID) with the centre of the cross indicating the location of the feature of interest, while the arms of the square cross make an acute angle of 45° with the strap's long axis. During the ion-beam thinning process, the marker may be viewed in cross-section from both sides of the sample alternately, and the coming together of the features relating to the arms of the cross indicates increasing proximity to the feature of interest. Although this approach does allow increased precision in locating the region of interest during thinning, it also increases the time required to complete the sample preparation. Hence, this method is particularly well suited to directly correlated multi-microscopy investigations in previously characterised material where high yield and the precise location are more important than preparation time. In addition to TEM lamella preparation, this method could equally be useful for preparing site-specific atom probe tomography (APT) samples.

Identification of the occurrence of minor elements in the structure of diatomaceous opal using FIB and TEM-EDS

AbstractThe occurrence of minor elements in the structure of biogenic diatomaceous opal-A is an important issue because it is closely related to biogeochemical processes driven by the precipitation, sedimentation, and storage of diatoms, as well as to the properties and applications of diatomite, which is the sedimentary rock composed of diatomaceous opal-A. However, to date, there is no direct microscopic evidence for the existence of minor elements, such as Al, Fe, and Mg, in the structure of diatomaceous opal-A, because such evidence requires observation of the internal structure of frustules to exclude the disturbance of impurity minerals, which is technically challenging using conventional techniques. In this work, transmission electron microscopy (TEM) and scanning electron microscopy (SEM) combined with energy-dispersive X-ray spectroscopy (EDS) mapping analysis were performed on diatomaceous opal-A from three typical diatomite specimens that were pretreated using focused ion beam (FIB) thinning. This technique produces a slice of a diatom frustule for direct TEM observation of the internal structure of the diatomaceous opal-A. The results of this work clearly indicate that minor elements, such as Al, Fe, Ca, and Mg, conclusively exist within the siliceous framework of diatomaceous opal-A. The contents of these minor elements are at atomic ratio levels of 1 (minor element)/10 000 (Si) – 1/100, regardless of the genus of the diatoms. The occurrence of minor elements in the internal structure is likely through biological uptake during biosynthesis by living diatoms. Moreover, surface coatings composed of aluminosilicates on diatom frustules are common, and the contents of elements such as Al and Fe are tens or hundreds of times higher in the coatings than in the internal siliceous structure of diatomaceous opal-A. The discovery of the incorporation of the above-mentioned minor elements in the diatomaceous opal-A structure, both in the internal Si-O framework and on the surface, updates the knowledge about the properties of diatomite.

Optimized pre-thinning procedures of ion-beam thinning for TEM sample preparation by magnetorheological polishing

Ion-beam-thinning is a well-established sample preparation technique for transmission electron microscopy (TEM), but tedious procedures and labor consuming pre-thinning could seriously reduce its efficiency. In this work, we present a simple pre-thinning technique by using magnetorheological (MR) polishing to replace manual lapping and dimpling, and demonstrate the successful preparation of electron-transparent single crystal silicon samples after MR polishing and single-sided ion milling. Dimples pre-thinned to less than 30 microns and with little mechanical surface damage were repeatedly produced under optimized MR polishing conditions. Samples pre-thinned by both MR polishing and traditional technique were ion-beam thinned from the rear side until perforation, and then observed by optical microscopy and TEM. The results show that the specimen pre-thinned by MR technique was free from dimpling related defects, which were still residual in sample pre-thinned by conventional technique. Nice high-resolution TEM images could be acquired after MR polishing and one side ion-thinning. MR polishing promises to be an adaptable and efficient method for pre-thinning in preparation of TEM specimens, especially for brittle ceramics.

Fabrication of nanoscale step height structure using atomic layer deposition combined with wet etching

The current techniques used for the fabrication of nanosteps are normally done by layer growth and then ion beam thinning. There are also extra films grown on the step surfaces in order to reduce the roughness. So the whole process is time consuming. In this paper, a nanoscale step height structure is fabricated by atomic layer deposition (ALD) and wet etching techniques. According to the traceable of the step height value, the fabrication process is controllable. Because ALD technology can grow a variety of materials, aluminum oxide (Al2O3) is used to fabricate the nanostep. There are three steps of Al2O3 in this structure including 8 nm, 18 nm and 44 nm. The thickness of Al2O3 film and the height of the step are measured by anellipsometer. The experimental results show that the thickness of Al2O3 film is consistent with the height of the step. The height of the step is measured by AFM. The measurement results show that the height is related to the number of cycles of ALD and the wet etching time. The bottom and the sidewall surface roughness are related to the wet etching time. The step height is calibrated by Physikalisch-Technische Bundesanstalt (PTB) and the results were 7.5±1.5 nm, 15.5±2.0 nm and 41.8±2.1 nm, respectively. This research provides a method for the fabrication of step height at nanoscale and the nanostep fabricated is potential used for standard references.

Fabrication of Vertical Array CNTs/Polyaniline Composite Membranes by Microwave-Assisted In Situ Polymerization.

A vertical array carbon nanotubes (VACNTs)/polyaniline (PANi) composite membrane was prepared by microwave-assisted in situ polymerization. With microwave assistance, the morphology of PANi revealed a smaller diameter and denser connection. Meanwhile, thermogravimetric analysis showed improved thermal stability of microwave-assisted PANi for higher molecular weight. Focused ion beam thinning method was used to cut the VACNTs/PANi membrane into dozen-nanometer thin strips along the cross-sectional direction, and transmission electron microscopy observation showed seamless deposition of PANi between VACNT gaps, without damaging the vertical status of CNTs. Meanwhile, stronger conjugate interaction between the quinoid ring of PANi and VACNTs of the composite membrane were prompted by microwave-assisted in situ polymerization. By using nanoindentation technology, the VACNTs/PANi composite membrane showed exponential increasing of modulus and hardness. Meanwhile, the elasticity was also improved, which was proved by the calculated plastic index. The results can provide helpful guidance for seamlessly infiltrating matrix into CNT array and also demonstrate the importance of structural hierarchy for getting proper behavior of nanostructures.

Transmission Electron Microscopy Study of Cr Poisoning of Lscf Cathodes

(La,Sr)(Co,Fe)O3-δ (LSCF) perovskite oxides have been considered to be a promising cathode material for SOFCs operating in the intermediate temperature range due to their significantly higher electrochemical activity for the O2 reduction reaction and higher oxygen ion conductivity than the conventional (La,Sr)MnO3 (LSM) cathode [1,2]. In practice, metallic materials have become a preferential choice for the interconnect due to their excellent physical and chemical properties. However the presence of chromium in all commonly used metallic alloys has been found to cause poisoning of the cathode under operating conditions leading to rapid electrochemical performance degradation of the cathodes including LSCF [3–5]. Development of a Cr tolerant cathode material for increased long-term durability of SOFCs relies on a fundamental understanding of the mechanism of the chromium deposition and poisoning of the cathode materials. Extensive research on the chromium deposition and poisoning processes on SOFC cathodes has been carried out but careful microstructural studies especially on the nanometer to atomic scale are very limited. This is however a subject that can give valuable information on the detailed process of Cr incorporation and evolution in the cathode materials, providing an important insight for the mechanistic understanding of the Cr poisoning. LSCF/CGO/LSCF symmetrical cells were prepared by screen printing the LSCF cathode on Gd doped cerium oxide (CGO) electrolyte pallet, and the effect of Cr poisoning at 900 ˚C in air on the electrochemical behavior of the cell was assessed by impedance spectroscopy. The change in nano/microstructure and chemistry between cells with and without Cr poisoning were studied in parallel by TEM/STEM/EDX/EELS. To facilitate the TEM sample preparation using focus ion beam thinning (FIB), bulk samples containing the porous LSCF layer were firstly embedded in an epoxy resin. Due to the peak overlap between the interested La and Cr and inherently poorer spatial resolution in EDX, EELS was employed with the aim for an improved accuracy in the analysis. Figure 1a shows an example of EDX artefacts where the spectrum from an epoxy area in between LSCF grains exhibit the presence of the LSCF elements. On the other hand, EELS could suffer a higher detection limit compared to EDX due the generally poorer signal to background (S/B) ratio, which is typically worse when the sample thickness increases. Figure 1b shows an example of EELS spectrum, which fails to detect the presence of Co in the thicker area of a LSCF grain (t/λ ~ 0.86). It was found that all the expected elements (apart from Sr) in LSCF can be successfully detected by EELS when t/λ < ~ 0.7, and this criteria was kept during all the later EELS measurements. Our results show that Cr is incorporated in LSCF in more complicated ways than a simple formation of SrCrOx as suggested by previous studies. Cr was found to segregate in Sr rich phases that also contain other elements such as Fe and Co (Figure 2). In addition, Cr was incorporated in the LSCF perovskite structure and repelled sometimes the other B site elements from the lattice. As a result, Cr rich phases take the form of various compositions such as (La,Sr)(Fe,Co,Cr)Ox, (La,Sr)(Fe,Cr)Ox and (La,Sr)CrOx (Figure 3). It is interesting to note that Cr appears to repel more readily Co than Fe. The Cr poisoning also promotes the formation of Co and Co-Fe rich phases that may contribute to the deficiency of Co in the LSCF grains (Figure 4). It can be seen that the area adjacent to the Fe-Co rich particles contains Cr and are deficient in Co with a composition close to that of (La,Sr)(Cr,Fe)Ox. Careful examination of Cr incorporation was also extended to LSCF grain boundaries with both structural and chemical analysis. The high-resolution microscopy results and their implications are discussed in relation to the degraded electrochemical properties of the LSCF cathode and the Cr poisoning mechanisms. [1] S. Jiang, Solid State Ionics 146 (2002) 1. [2] A. Esquirol, N.P. Brandon, J.A. Kilner, M. Mogensen, J. Electrochem. Soc. 151 (2004) A1847. [3] M.C. Tucker, H. Kurokawa, C.P. Jacobson, L.C. De Jonghe, S.J. Visco, J. Power Sources 160 (2006) 130. [4] L. Zhao, J. Drennan, C. Kong, S. Amarasinghe, S.P. Jiang, ECS Trans. 57 (2013) 599. [5] S.P. Jiang, X. Chen, Int. J. Hydrogen Energy 39 (2014) 505. Figure 1

Purity and resistivity improvements for electron-beam-induced deposition of Pt

Electron-beam-induced deposition (EBID) of platinum is used by many researchers. Its main application is the formation of a protective layer and the “welding material” for making a TEM lamella with a focused ion beam thinning process. For this application, the actual composition of the deposition is less relevant, and in practice, both the mechanical strength and the conductivity are sufficient. Another important application is the creation of an electrical connection to nanoscale structures such as nano-wires and graphene. To serve as an electrical contact, the resistivity of the Pt deposited structure has to be sufficiently low. Using the commonly used precursor MeCpPtMe3 for deposition, the resistivity as created by the basic process is 10+5–10+6 higher than the value for bulk Pt, which is 10.6 µΩ cm. The reason for this is the high abundance of carbon in the deposition. To improve the deposition process, much attention has been given by the research community to parameter optimization, to ex situ or in situ removal of carbon by anneal steps, to prevention of carbon deposition by use of a carbon-free precursor, to electron beam irradiation under a high flux of oxygen and to the combination with other techniques such as atomic layer deposition (ALD). In the latter technique, the EBID structures are used as a 1-nm-thick seed layer only, while the ALD is used to selectively add pure Pt. These techniques have resulted in a low resistivity, today approaching the 10–150 µΩ cm, while the size and shape of the structure are preserved. Therefore, now, the technique is ready for application in the field of contacting nano-wires.

Mineralogy and defect microstructure of an olivine-dominated Itokawa dust particle: evidence for shock metamorphism, collisional fragmentation, and LL chondrite origin

We report here detailed analytical scanning and transmission electron microscopic investigations on an olivine-dominated dust particle (RB-QD04-0042) from the surface of asteroid 25143 Itokawa. The dust particle was returned to Earth by the Hayabusa spacecraft and was made available in the context of the first announcement of opportunity for Hayabusa sample investigation. Multiple thin slices were prepared from the precious particle by means of focused ion beam thinning, providing a unique three-dimensional access to its interior. The 40 × 50 μm sized olivine particle contains a spherical diopside inclusion and an intimate intergrowth of troilite and tetrataenite. The compositions of olivine (Fo69Fa31) and diopside (En48Wo42Fs10), as well as the high Ni content of the sulfide-metal alloy, indicate a LL ordinary chondrite origin in accord with previous classifications. Although no impact crater exists at the surface of RB-QD04-0042, transmission electron microscopy revealed the presence of various shock defects in constituent minerals. These defects are planar fractures and [001] screw dislocations in olivine, multiple {101} deformation twins in tetrataenite and basal (0001) stacking faults in troilite. These diagnostic shock indicators occur only in a small zone on one concave side of the dust particle characterized by a high fracture density. These observations can be explained by a collisional event that spalled off material from the particle's surface. Alternatively, the dust particle itself could be a spallation fragment of an impact into a larger regolith target. This suggests that Itokawa dust particles lacking visible microcraters on their surfaces might have still experienced shock metamorphism and were involved in collisional fragmentation that resulted in the formation of regolith.

Modified Saddle Field Ion Source Using A Ring Focusing Electrode

<b> </b>An experimental study of a dc saddle field ion source is reported with a view to maximizing the beam current and insuring extended operation of the source. The dependence of the beam current on geometrical and operational parameters is studied. The electrical characteristics of a dc saddle field discharge were studied using nitrogen gas. This study includes the experimental arrangement for ion beam production from nitrogen gas under the influence of discharge voltages applied to the focusing electrode. Also, different focusing hole diameters are examined and optimized to get a highest efficiency of the ion source. A focusing electrode in the form of a ring is placed at 4 mm from the ion source exit. Different ring electrodes with different exit hole diameters (5, 7, 9, and 11 mm) were used as focusing electrodes. The optimum hole diameter for the focusing electrode was found to be 9 mm where maximum ion beam current can be obtained. It was found that at 9 mm hole diameter, focusing voltage = - 3 kv, and pressure P<SUB>r</SUB> = 8x10<SUP>-4</SUP> mbar using nitrogen gas at distance between two anode rods= 6 mm, discharge region = 5 mm, an ion beam current of 243 µA could be obtained. These data are important for ion beam sputtering, ion beam thinning and in other several applications.

Optimization of the preparation of GaN-based specimens with low-energy ion milling for (S)TEM

We report on optimization of electron transparent GaN based specimens for transmission electron microscopy (TEM) and scanning TEM (STEM) studies by combining focused ion beam thinning and low-energy (≤500eV) Ar-ion milling. Energy dependent ion milling effects on GaN based structures are investigated and the quality of ion milled samples is compared with that of specimens prepared by wet chemical etching. Defects formed during ion milling lead to amorphization of the specimen. The experimental results are compared with Monte-Carlo simulations using the SRIM (stopping and range of ions in matter) software. Specimen thickness was deduced from high-angle annular dark field STEM images by normalization of measured intensities with respect to the intensity of the scanning electron probe and comparison with multislice simulations in the frozen lattice approach. The results show that the thickness of the amorphous surface layer can be successfully reduced below 1nm by low energy ion milling, leading to a homogeneous image contrast in TEM and STEM, so that good conditions for quantitative analysis can be achieved. For an ion energy of 400eV the thickness measurements resulted in an etching rate of about 6–8nm/min.

Atomic-scale effects behind structural instabilities in Si lamellae during ion beam thinning

The rise of nanotechnology has created an ever-increasing need to probe structures on the atomic scale, to which transmission electron microscopy has largely been the answer. Currently, the only way to efficiently thin arbitrary bulk samples into thin lamellae in preparation for this technique is to use a focused ion beam (FIB). Unfortunately, the established FIB thinning method is limited to producing samples of thickness above ∼20 nm. Using atomistic simulations alongside experiments, we show that this is due to effects from finite ion beam sharpness at low milling energies combined with atomic-scale effects at high energies which lead to shrinkage of the lamella. Specifically, we show that attaining thickness below 26 nm using a milling energy of 30 keV is fundamentally prevented by atomistic effects at the top edge of the lamella. Our results also explain the success of a recently proposed alternative FIB thinning method, which is free of the limitations of the conventional approach due to the absence of these physical processes.

OS0315 純マグネシウム中に導入される変形双晶の原子構造

In order to clarify the atomic structure of deformation twin boundary in pure magnesium, 99.9 % purity magnesium single crystal was prepared by modified Bridgeman technique. Thin foils were thinned by a mechanical polishing, a mechanical gliding and ion-beam thinning. The microstructure and the atomic structure of the twin boundary of magnesium were observed by transmission electron microscopy (TEM) and high resolution TEM. In this study, all of the observed twins were lenticular {1012} twins with curved and straight regions. In both regions, it was found that these twin boundaries consisted of the symmetric tilt boundary planes and the (0001) faceted planes. The atomic structure of symmetric tilt boundary plane on these twins corresponded to the calculated atomic structure of {1012} twin boundary. It was also found that the curved region was a step-like structure and the straight region was a zig-zag structure.

Effects of heat treatment on the structure of LDPE-derived solid carbons

Heat treatment of spherical solid carbons produced by pyrolysis of low-density polyethylene (LDPE) gave faceted particles with spherical geometry. The changes in the structure of the heat-treated (HT) carbons in the temperature range 1300–2600°C were characterized by elemental analysis, X-ray diffraction (XRD), temperature-programmed oxidation (TPO), Raman spectroscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM) which was also used in conjunction with the focused ion beam (FIB) thinning. The HT carbons gave interlayer spacing (d002) values close to that of graphite, however, the maximum values of La and Lc (around 20nm) were significantly lower than those of graphite. The TPO profiles showed that the HT carbons contain domains with different structural order and that the contribution of the more ordered domains increases with the increasing treatment temperature. The SEM and TEM examination showed faceting of the initial spherules and FIB analysis showed concentric carbon aromatic layers in a core shell structure. The extent of ordering in the coherent domains increased in the radial direction suggesting that the growth of crystallites was constrained by the size of the initial carbon spherules.

FCC Surface Precipitation in Cu-Zn-Al after Low Angle GA&lt;SUP&gt;+&lt;/SUP&gt; Ion Irradiation

The precipitation of a disordered FCC surface structure after low angle Ga + ion irradiation during focused ion beam thinning of a B2 Cu-Zn-Al alloy with e/a = 1.48 is reported. Conventional as well as high-resolution transmission electron microscopy techniques reveal FCC layers on both sides of the thinned sample. The occurrence of this structure is attributed to disordering and dezincification of the alloy resulting from the sputtering process during the irradiation. Changes in crystallographic sample orientation with respect to the incoming ion beam do not have a significant effect on the appearance of the FCC surface structure.

Scanning Auger of a specific via interface in an integrated circuit using a novel focused ion beam sample preparation technique

Auger depth profile analysis can be impeded by surface roughening during ion sputtering. This is especially noticeable when analyzing semiconductor devices because of the variety of materials that are susceptible to roughening, as well as the importance of very thin interfaces. A novel technique is presented in this article, which combines scanning Auger analysis with focused ion beam (FIB) thinning for analysis of single via interfacial structures in integrated circuit devices. After a failing structure was identified by electrical fault isolation techniques, FIB was used to remove all of the materials from the top of the device. The materials include polyimide, passivation, metal layers, and dielectric layers. The layers were removed to a level approximately 100Å above the via interface under a tungsten plug. A scanning Auger instrument was then used for Auger depth profiling of the single via. A thin oxidized interface was observed between Ti∕TiN glue layer and antireflection coating (ARC) TiN and was identified as the cause of the via failure. It would have been impossible for conventional sputter depth profiling to detect this thin oxidized layer buried under several layers of materials. Further investigation showed that the interfacial oxide is caused by backsputtering of ARC TiN during via etch and rf sputtering before Ti∕TiN glue deposition.

Cross-section transmission electron microscopy of the ion implantation damage in annealed diamond

It has formerly been shown that low-damage levels, produced during the implantation doping of diamond as a semiconductor, anneal easily while high levels “graphitize” (above about 5.2 × 10 15 ions/cm 2). The difference in the defect types and their profiles, in the two cases, has never been directly observed. We have succeeded in using cross-section transmission electron microscopy to do so. The experiments were difficult because the specimens must be polished to ∼40 μm thickness, then implanted on edge and annealed, before final ion beam thinning to electron transparency. The low-damage micrographs reveal some deeply penetrating dislocations, whose existence had been predicted in earlier work.