[en] In this paper, during dopant analysis of silicon devices, we have observed a phenomenon generally neglected in EDX analysis: the coherent Bremsstrahlung (CB). We discussed the reason why and came to the conclusion that the analytical TEM used for these experiments presents a configuration and performances, which makes this equipment very sensitive to the CB effect. This is due to large collection solid angle and high counting rate of the four silicon drift EDX detectors (SDD), a high brightness electron source providing large probe current and moreover a geometry favorable to on axis crystal observations. We analyzed silicon devices containing Si [110] and Si [100] crystal areas at different energies (80–120–200 keV). We also observed relaxed SiGe (27 and 40 at% of Ge). The CB effect, whose intensity is maximum near zone axis beam alignment, manifests as characteristic broad peaks present in the X-ray spectrum background. The peak energies are predicted by a simple formula deduced for the CB models found in the literature and that we present simply. We evaluate also the CB peak intensities and discuss the importance of this effect on the detection and quantification traces of impurities. The CB peaks also give information on the analyzed crystal structure (measurement of the periodicity along the zone axis) and allow, in every particular experiment or system, to determine the median take off angle of the EDX detectors. -- Highlights: ► STEM EDX dopant distribution analysis (As and P) in Si devices is carried out. ► High brightness electron source and four EDX Silicon Drift detectors are used. ► The obtained signal dynamics (four decades) allows detection down to 0.01 at%. ► During silicon axis analysis coherent Bremmsstrahlung is observed. ► This effect is studied at different energies and Si crystal orientations.

[en] The radial variations of radiative and metastable atom densities in an argon plasma column produced by a microwave surface wave are obtained. A large variety of radial profiles is observed as a function of wave frequency (300-1000 MHz), gas pressure (50-200 mTorr), tube diameter (17.5-34 mm) and axial magnetic field. The results differ significantly from those reported for the dc positive column, where the radial distributions keep approximately the same Jsub(o) Bessel-like profile

[en] The propagation of electron surface waves can be used to sustain long plasma columns. The relation between the axial distribution of the electron density observed along the plasma column and the corresponding power distribution of the surface wave that produces it is investigated. It is found that the electron density decreases almost linearly along the plasma column in the direction of the wave propagation. This is explained by assuming that the number of electrons produced over a given axial length is proportional to the wave power absorbed over that same length

[en] Three vicinal faces of rhenium, close to the (0001) basal plane have been studied by Low Energy Electron Diffraction (LEED), Auger Electron Spectroscopy (AES) and Mirror Electron Microscopy (MEM). The deviation from the base orientation varied between 2⁰ and 6⁰ and atomic steps of various densities were observed. The sticking coefficient at 350 K, is found constant and equal to 0.53 when the oxygen coverage varies from 0 to 0.5 monolayer and then decreases rapidly. The surface potential of Re(0001) initially decreases by -30 meV and then increases linearly to saturate at +700 meV. On the Re-(S)[14(0001) X (112^-0)] face, the surface potential variations are quite different and the saturation occurs at +1050 meV. The study of the LEED patterns during the oxidation on different stepped surfaces of rhenium, indicates that the structure, observed on Re(0001) and usually referred to as a p(2 x 2) structure, could also be interpreted as a p(2 x 1) structure with three possible orientations. A model for the oxidation is finally given which can account for these various observations. (Auth.)

[en] A continuous measurement of the surface potential variation of niobium during oxygen adsorption has been made on (100), (110) and (111) single crystals, at room temperature, in the 5 x 10^-9 -5 x 10^-7 Torr oxygen pressure range. The method consisted of using together a mirror electron microscope, an Auger analyser and a low energy electron diffractor. The curves of work function variation Δphi against oxygen exposure show four distinct regions. The first corresponds to a work function decrease until approximately a 0.5 L oxygen exposure. Under these conditions, a first surface structure is formed which appears clearly on the (110) LEED pattern. The second region shows a work function increase while a new structure is being formed, which corresponds to a full layer and a periodicity half of the former. During these two periods, the Auger analysis indicates that the sticking coefficient remains close to unity, independently of the oxygen pressure. The third region shows a linear increase of the work function with the oxygen exposure. The sticking coefficient varies inversely as the oxygen pressure but the slope dΔphi/dt is pressure independent. This region corresponds to the building of a chemisorbed monolayer above the surface structure, which, for each face, at room temperature, is completed in a given time when the pressure remains in the 5 x 10^-9 -5 x 10^-8 Torr range. The last region of the Δphi curves corresponds mainly to molecular physisorption. A comparison between the three chosen faces is finally given. (Auth.)

[en] The growing demand for wireless multimedia applications (smartphones, tablets, digital cameras) requires the development of devices combining both high speed performances and low power consumption. A recent technological breakthrough making a good compromise between these two antagonist conditions has been proposed: the 28-14nm CMOS transistor generations based on a fully-depleted Silicon-on-Insulator (FD-SOI) performed on a thin Si film of 5-6nm. In this paper, we propose to review the TEM characterization challenges that are essential for the development of extremely power-efficient System on Chip (SoC)

[en] In this paper we present the different imaging based techniques used in the semiconductor industry to support both manufacturing and R and D platforms at STMicroelectronics. Focus is on fully processed devices characterization from large structure (3DI, Imager sensors) to advanced MOS technologies (28-20 nm). Classical SEM and TEM (mainly EFTEM) based techniques are now commonly used to characterize each step of the semiconductor devices' process flow in terms of morphology and chemical analysis. However to address specific issues, dedicated imaging techniques are currently being investigated. With the 'High-k Metal Gate' stack involved in the more advanced MOS devices (28-20 nm), new challenges occur and therefore advanced characterization is mandatory. Some relevant examples are pointed out through (STEM) EELS and EDX experiments. Analysis of stressors mainly used to improve carrier mobility in next generation devices, is also presented with different approaches (NBD, CBED and Dark-field holography). Advanced STEM and AFM based techniques applied to characterize dopants and junction in MOS devices and also in more relaxed structure such as imager sensors is discussed too. Concerning back-end (interconnects) and 3D integration (3DI) issues, focus is on nano-characterization of defects by classical techniques (EFTEM, STEM EELS-EDX) and with dedicated ones still in development. To illustrate this topic some 3D FD3/SEM and E-beam tomography experiments are presented. Examples of microstructure and texture determination in poly-crystalline materials such as copper line by coupling SEM/EBSD and TEM techniques are also shown.

[en] In this paper we evaluate sensitivity limits and applications of scanning transmission electron microscopy (STEM) energy-dispersive X-ray (EDX) spectroscopy technique for the mapping of arsenic dopant distribution in nanometer range silicon devices. First we show that lamella radiation damages, generated by the intense focused electron probe at 200 keV, are significantly reduced at 120 keV. This allows to use high electron doses and therefore to improve the EDX sensitivity. The analysis of 45nm nMOS transistor clearly shows the n doped areas and local segregation in gate and spacers.

[en] The robust development of exotic devices strongly relies on physical characterization to better understand the stacked layers architecture and the resulting morphology. In such a context, a silicon nanowire, 200nm long and of around 15nm of diameter, encapsulated by a high-k metal gate stack (TiN/HfSiON) of few nanometers per layer, is characterized by 2D and 3D X-ray energy dispersive spectroscopy in a STEM to evaluate the process flow methodology

[en] There is a need to measure the dopant potentials and strain fields in semiconductor materials with nm-scale resolution. Here we show that off-axis electron holography is a powerful technique that can be used to measure the fields present in a high-k metal gate 28-nm node nMOS device with a contact etch stop liner stressor. Off-axis electron holography has been used to map the positions of the active dopants with a spatial resolution of 1 nm. The experimental results have been compared to electron energy loss spectroscopy maps. Finally, dark field electron holography has also been used to provide strain maps and the experimental results have been verified using nanobeam electron diffraction.