High Voltage Scanning Electron Microscope Research Articles

Measurement and Interpretation of Strain Relaxation in Passivated Al-0.5%Cu Lines

ABSTRACTX-ray diffraction was used to measure the strain relaxation in passivated Al-0.5%Cu lines at 200°C after cooling directly from an anneal at the passivation deposition temperature. The strain decay is fit with a stress-assisted, thermally-activated relaxation model. A high-voltage scanning electron microscope was used to image the presence and growth of voids through the passivation. The time scale of the void growth is not the same as that of the hydrostatic relaxation, indicating that voiding is not solely responsible for the observed relaxation. The relaxation of the line is modeled using a von Mises yield criterion and allowing elastic compliance of the passivation. The magnitude of the calculated relaxation agrees with the measurements. It is suggested that a combination of voiding and passivation compliance is responsible for the measured hydrostatic strain relaxation.

Non-Destructive Evaluation of Strains and Voiding in Passivated copper Metallizations

AbstractStress induced voiding in passivated Cu lines was investigated by x-ray strain analysis and in-situ high voltage scanning electron microscope (HVSEM) techniques. Cu lines on a Ta underlayer and Cu lines on an Al underlayer were patterned by a trilayer liftoff technique and passivated with Si3N4. For direct observation of stress voiding, specimens were heated to 350°C in the HVSEM and then cooled and held at 150°C. Identical samples were subjected to the same thermal cycle for strain state determination using x-ray techniques. The hydrostatic stress state at each temperature was calculated from the measured strains. Few initial voids were observed after passivation in either sample. After heating to 350°C and cooling to the dwell temperature, no new voiding was seen in the Ta/Cu lines. Measured hydrostatic strains were half those measured in the Al/Cu lines. Heavy voiding was observed in the Al/Cu lines after cooling to the dwell temperature.

Non-Destructive Evaluation of Strains and Voiding in Passgvated Copper Metallizations

ABSTRACTStress induced voiding in passivated Cu lines was investigated by x-ray strain analysis and in-situ high voltage scanning electron microscope (HVSEM) techniques. Cu lines on a Ta underlayer and Cu lines on an Al underlayer were patterned by a trilayer liftoff technique and passivated with Si3N4. For direct observation of stress voiding, specimens were heated to 350ºC in the HVSEM and then cooled and held at 150ºC. Identical samples were subjected to the same thermal cycle for strain state determination using x-ray techniques. The hydrostatic stress state at each temperature was calculated from the measured strains. Few initial voids were observed after passivation in either sample. After heating to 350ºC and cooling to the dwell temperature, no new voiding was seen in the Ta/Cu lines. Measured hydrostatic strains were half those measured in the Al/Cu lines. Heavy voiding was observed in the Al/Cu lines after cooling to the dwell temperature.

Submicroscopic structure of the TTT-TCNQ conductive network in reticulate-doped polymers revealed by SEM

The results obtained using high-voltage scanning electron microscopy (SEM), which enables observation of the structure of the conductive network within the surface layer of reticulate-doped polymer films, are reported. The submicroscopic structure of the tetrathiotetracene-tetracyanoquinodimethane (TTT-TCNQ) network in amorphous polymers is presented and its implications for the conductivity mechanism are discussed. The SEM pictures obtained reveal the fibrous internal structure of the conductive network in bulk-conductive films obtained using the amorphous polymers polycarbonate and poly(methylmethacrylate). TTT-TCNQ crystallites in the surface-conductive film have a different form in spite of the same polymer being used as the matrix.

Low Voltage Sen for Unique Surface Analysis of Prosthetic Devices

AbstractSurgical manipulation of plastic prostheses using metal instruments is likely to produce surface damage and surface roughness which may compromise biocompatibility of implants due to tissue irritation and increased cellular or bacterial adhesion. There are virtually no data in the literature concerning the clinical occurrence and consequences of manipulative surface damage to implants. We have found that conventional high voltage scanning electron microscopy techniques (HVSEM) obscure surface defects on plastics due in large measure to beam energy “healing” by local melting. This paper reports the use of low voltage SEM (LVSEN) at low beam voltages (<1.5keV) and without the need for conductive carbon or Au/Pd coatings for examination of plastic device surfaces before and after normal surgical manipulation. Results for intraocular lens implants, a major human prosthesis, clearly demonstrate that standard surgical procedures can produce significant implant surface damage which may not be observed by normal SEN analysis. LVSEN has been shown to readily visualize such previously unobserved surface defects in model surgical manipulation experiments. These results have important implications for more reliable polymer surface characterization and for development of improved prosthetic devices, instruments, and implant surgery.

A simple high-voltage electron microscope voltage stabiliser using current-regulated corona tubes

Corona stabiliser tubes have been found to possess an inherent instability of less than 10 p.p.m. over at least one minute suggesting their use in simple and economical low-current voltage stabilisers for the range 100 kV to 1 MV. The testing and the use of these tubes in a current-regulated 800 kV stabiliser in the Arizona high-voltage scanning electron microscope is described together with protection measures required for reliable operation.

High Resolution, Low Accelerating Voltage Scanning Electron Microscopy of Uncoated, Non-Conducting Surfaces

Recent improvements in the design of the Coates and Welter field emission electron gun have resulted in very small probe sizes (less than 50A) with low voltage (0.5 to 2 KV) electron beams operated at probe currents in excess of 1 nanoampere. Such weak electrons do not penetrate deeply into the sample. This results in images which often show more topographical detail of surface features than can be obtained using conventional high voltage scanning electron microscopy. At low voltages, the number of secondary electrons produced for each primary electron in the beam is often greater than one.

The observation of domain structures in grain oriented Si-Fe using a high voltage scanning electron microscope

It has been known for some time that the condition of the steel surface influences the magnetic properties of grain oriented Si-Fe. Domain observations with a scanning electron microscope have confirmed that in misoriented grains the closure domain structures on rough surfaces are more complex than those on polished surfaces.

Magnetic Domain Observation of an Amorphous Fe-Si-B Ribbon by Means of a High Voltage Scanning Electron Microscope

Magnetic domains of ferromagnetic amorphous ribbon have been observed using Bitter powder method. However, the domains of amorphous ribbon are very complicated and the surface of ribbon is not flat, so that clear domain image has not been obtained. It has been desired to observe more clear image in order to analyze the domain structure of this zero magnetocrystalline anisotropy material. So, we tried to observe magnetic domains by means of a back-scattered electron mode of high voltage scanning electron microscope (HVSEM).HVSEM method has several advantages compared with the ordinary methods for observing domains: (1) high contrast (0.9, 1.5 and 5% at 50, 100 and 200 kV) (2) high penetration depth of electrons (0.2, 1.5 and 8 μm at 50, 100 and 200 kV). However, image resolution of previous HVSEM was quite low (maximum magnification was less than 100x), because the objective lens cannot be excited for avoiding the application of magnetic field on the specimen.

High Magnification Observation of Magnetic Domains by Means of a High Voltage Scanning Electron Microscope

The resolution of a magnetic domain image in the backscattered electron mode of a high voltage scanning electron microscope was determined from the diameter of an electron probe. The probe diameter was reduced from 2 µm to 0.06 µm by attaching an objective lens whose magnetic field around the specimen was shielded. The maximum magnification giving a clear image was improved from 100 to 3000× by attaching the shielded objective lens. The shape of zig-zag domains (about 1.9 µm spacing) appearing on the crossed region between the in-plane domain and the stripe domain of amorphous 80%Fe-8%Si-12%B ribbon was clearly resolved by using the shielded objective lens.

Domain and grain observations using a colloid technique for grain-oriented Si-Fe with coatings

New effective domain and grain observation methods using a ferromagnetic-colloid technique are presented for highly-oriented Si-Fe with the tensile coating. A dc field of about 50 Oe is applied perpendicular to the sheet plane for domain observations, while a dc field of about 90 Oe is applied parallel to the sheet plane for grain and grain-boundary observations on the coating. These simple observation techniques are considered to be suitable for product inspections because there are no limitations to the sample size or the observed area on the coating as is the case with domain observation using a high-voltage scanning electron microscope (SEN).

Observation through surface coatings of domain structure in 3% Si-Fe sheet by a high voltage scanning electron microscope

Direct observation of magnetic domains in commercial oriented silicon-iron sheet has recently been made possible even under insulating coatings by use of a high voltage scanning electron microscope(SEM). Detailed description is given of the technique for the domain observation. Also, the effects of coatings on domain structure in slit and sheared oriented silicon-iron sheet are shown on the basis of the observation. Variation of domain structure by shearing was insignificant, depending neither on the kind of coating nor on the sheared width. Stress pattern of about 0.5mm width was observed only at the sheared edge. On both surfaces of slit specimen coated with conventional phosphate, clear stress pattern appeared about 1.5mm away from the slit edge. This indicates that slitting induced transverse tensile stress in the specimen. Width of the stress pattern was 5∼15mm, independent of slitting width. In specimen with silica-phosphate coating, the stress pattern was hardly observable. Domain observation after removing silica-phosphate coating or applying compressive stress and magnetostriction measurement indicate that longitudinal tensile stress of about 0.5kg/mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> given by the silica-phosphate coating cancelled the induced transverse tensile stress, suppressing the generation of [100] and [010] domains.

Magnetic domain contrast in backscattered electron images obtained with a scanning electron microscope

Abstract Magnetic domain contrast in backscattered electron images of an iron-3% silicon specimen has been measured at 50–200 kV by using a high-voltage scanning electron microscope, and a detailed study has been made of the dependence of the contrast on detection direction and accelerating voltage. The contrast is maximum at a take-off angle of about 60° for both 45° and 60° specimen tilts. The contrast is approximately proportional to the 3/2 power of the accelerating voltage, as shown by Newbury, Yakowitz and Myklebust (1973) and by Fathers, Jakubovics, Joy, Newbury and Yakowitz (1973 b, 1974). The resolution of domain images and the material depth effective for the magnetic contrast have been studied. They are also dependent on the detection direction: the resolution is high and the depth is small at a lower take-off angle than that corresponding to the mirror-symmetrical direction, whereas they are low and large, respectively, at a higher take-off angle. The contrast mechanism is also discussed on the basis of Monte Carlo calculation data.

Observed depths of magnetic domains in high-voltage scanning electron microscopy

The increased electron penetration using a high voltage scanning electron microscope enables one to discern internal domains. The maximum material depth contributing to magnetic contrast and resolution of domains are experimentally determined at 50 to 200 kV. The results are compared with the electron trajectories already shown by the Monte Carlo calculation. Domains of SiFe having unusual surfaces, e.g., with deformation layer and with special coating, are observed. The depths observed of domains are also estimated. Die große Elektroneneindringtiefe bei einem Hochspannungs-Scanning-Elektronenmikroskop erlaubt, innere Domänen aufzufinden. Die maximale Materialtiefe, die zum magnetischen Kontrast beiträgt, und die Auflösung der Domänen werden experimentell bei 50 bis 200 kV bestimmt. Die Ergebnisse werden mit Elektronenbahnen verglichen, die bereits durch Monte-Carlo-Berechnungen erhalten wurden. SiFe-Domänen mit ungewöhnlichen Oberflächen, z. B. mit Deformationsschichten und mit speziellen Bedeckungen, werden beobachtet. Die beobachteten Domänentiefen werden ebenfalls berechnet.

High Contrast Observation of Magnetic Domain with High Voltage SEM

The analysis and experiments on the observation of the type II magnetic contrast in a backscattered electron image by using a high voltage scanning electron microscope are described. Although the reduction in the spatial resolution of the magnetic contrast due to the enlargement of the diffusion area of the penetrating electron probe is unavoidable, this approach of using a high voltage scanning electron microscope is very effective for increasing the magnetic contrast, and it seems a very useful means of studying the magnetic materials for practical use such as Mn-Zn ferrite and others.

Line patterns in wide-angle convergent beam electron diffraction

Wide-angle convergent-beam electron diffraction patterns from thin single crystals show sets of parallel lines somewhat similar to Kikuchi or Kossel lines. In some cases, each line separates into a black and white line pair when the electron beam is defocused. It is shown that this separation depends on the curvature of the crystal. A method for analysis of the line geometry is proposed which takes into account the aberrations of the electron lens. Using a high-voltage transmission scanning electron microscope, through-focus series of patterns from graphite crystals have been obtained and analyzed to give values for the radius of curvature of the crystal. In defocussed patterns the distortions of the lattice by defects are clearly visible.