The paper proposes a method for solving a three-dimensional tomography problem using data from a scanning electron microscope in the backscattered electron detection mode. Based on the assumption that the sample has a three-layer structure, analytical expressions were constructed for the dependence of the intensity of the detected signal on the chemical composition of the sample, the thickness of the layers, and the energy of the primary electrons. Based on the obtained analytical expressions, using the example of a three-layer (aluminium-gold-silicon) structure, the inverse problem of reconstructing the thicknesses of the aluminum and gold layers is solved in two different formulations, depending on the type of a priori information available about the structure of the sample.

— New possibilities for the mode of detecting backscattered electrons in a scanning electron microscope (SEM) are presented. The technique for determining the chemical composition of the probed area of the sample using the precalibrated scale of the SEM’s gray screen has been further developed. Simple relationships are presented for practical application in finding the thicknesses of thin films on a massive substrate. The parameters of the double layer of the film nanostructure on the substrate are determined, that is, depth and thickness of subsurface fragments of the microobject. A technique is proposed for measuring the surface potential of negatively charged dielectric samples upon irradiation with medium-energy electrons.

The calculated ratios of the signal of backscattered electrons for multilayer nanostructures are derived depending on the energy of probing electrons and the composition of multicomponent samples. From experimentally measured signals and calculated ratios, not only thicknesses, but also, for the first time, depths of occurrence of local microheterogeneities of three-dimensional nanostructures were determined. The studies were carried out by a non-destructive method for detecting backscattered electrons in a scanning electron microscope.

The calculated ratios of the signal of backscattered electrons for multilayer nanostructures are derived depending on the energy of probing electrons and composition of multicomponent samples. From experimentally measured signals and calculated ratios, not only thicknesses but also, for the first time, depths of occurrence of local microheterogeneities of three-dimensional nanostructures were determined. The studies were carried out by a non-destructive method of detecting backscattered electrons in a scanning electron microscope. Keywords: multilayer nanostructures, scanning electron microscopy.

Comparative studies are performed on the fundamental characteristics of charging classical dielectrics (PMMA) and ferroelectrics (LiNbO 3 ) upon ion irradiation. Samples in experiments are irradiated with Ar + ions having energies of 5–10 keV. General patterns are revealed in the kinetics of charging and typical differences in the characteristics of the current of the emitted ions, the displacement current (charge accumulation), and the surface potential. The first characteristic feature of charging ferroelectrics is the emergence of additional current in the detecting devices (the current of repolarization). The second feature is the presence of a double layer of charges on the surfaces of ferroelectrics. This double layer affects all kinetic characteristics of charging.

An experimental system for detection of back-scattered electrons (BSE) in the scanning electron microscope (SEM) for three-dimensional (3D) visualization of the microstructure topography is described. The 3D surface topography reconstruction is carried out according to the algorithm of profile reconstruction from the preliminarily determined angular dependencies of BSE with the use of a calibration specimen. It is shown that the instrument function of the detector system, i.e., the detector response function, as well as the geometric factor, that takes the transformation of the angle distribution for single and multiple scattering of BSEs into consideration, cause a significant impact on the detected signal.

A new configuration of semiconductor detectors for backscattered electrons for a scanning electron microscope (SEM) is presented. The result of the optimization was the possibility to extract the information about the spatial relief (3D topology) of the sample and its subsurface structure (3D tomography) in the simplest way. The detector consists of 8 sensors-semiconductor plates, positioned in a certain way. The proposed method was tested on real structures having a surface micro relief or a subsurface volume structure. Experiments and simple calculations show increased effectiveness and a high signal-noise ratio in the proposed method. This is important, particularly for studying the radiation-sensitive biomedical tissue in SEM.

We propose a new SFS (shape from shading) technique for improved 3D surface reconstruction and imaging of relatively smooth surface topography using the scanning electron microscope (SEM). The new arrangement of backscattered electrons detector plates allows decreasing the initial energy of the electron probe, which makes this SEM technique to be suitable for usage on radiation-sensitive samples like biological tissues. Experiments show high effectiveness of the method, which improves both the gradient sensitivity of the signal and the signal to noise ratio.

AbstractThe charging kinetics of Al_2O_3 (sapphire) and SiO_2 (α-quartz) dielectrics irradiated by inert gas ions (Ar^+), metal ions (Ga^+), and protons (H^+) has been studied. It has been found that charging kinetics depends considerably on the type of irradiating ion. Also, it has been established that preirradiation of a dielectric target by an ionizing corpuscular radiation (protons, ions) substantially changes the charge characteristics of the dielectric surface. These differences depend on irradiating ion energy, which governs the depth of an accumulated negative charge layer versus the depth of ion preimplantation.

The main angular characteristics and resulting semi-empirical equations for back-scattered electrons of medium energy (1–30 kV) are calculated. The results from an analysis are used to develop an optimized detector system of back-scattered electrons for scanning electron microscopes to visualize subsurface microstructures and improve topographic contrast. These results contribute to solving problems of the three-dimensional visualization of surface topography and selective tomography of the subsurface architecture of micro-objects.

The charging kinetics of Al 2 O 3 (sapphire) and SiO 2 (α-quartz) dielectrics irradiated by inert gas ions (Ar + ), metal ions (Ga + ), and protons (H + ) has been studied. It has been found that charging kinetics depends considerably on the type of irradiating ion. Also, it has been established that preirradiation of a dielectric target by an ionizing corpuscular radiation (protons, ions) substantially changes the charge characteristics of the dielectric surface. These differences depend on irradiating ion energy, which governs the depth of an accumulated negative charge layer versus the depth of ion preimplantation.

A concise critical analysis of possible methods for measuring the suface potentials of dielectric targets under medium-energy electron-beam irradiation in a scanning electron microscope is carried out. The advantages of studying charging kinetics by recording a shift in the entire energy spectrum of emitted electrons are shown. Two new methods of surface-potential estimation are proposed: using the cathodoluminescence signal and the signal of backscattered electrons. It is found that the total energy of electrons reflected from charged dielectric targets is several times greater than the energy of electrons reflected from an uncharged dielectric.

Lightning inside the chamber of a scanning electron microscope (SEM), caused by electrons being scattering from a sample (and parts of the chamber), is observed and analyzed. These electrons generate the luminescence in a Thornly–Everhart collector. This parasitic effect (artifact) must be considered and eliminated in all experiments with the cathodoluminescent (CL) mode of SEM. A new technique for measuring surface potential on dielectric samples is proposed. It is based on variations in the CL signal during electron irradiation of a sample in SEM.