Influence of the Emitter Shape on the Field-of-View in Atom Probe Tomography.

Atom probe tomography (APT) is a unique analytical technique that offers three-dimensional elemental mapping with a spatial resolution down to the sub-nanometer. When APT is applied on complex heterogenous systems and/or under certain experimental conditions, that is, laser illumination, the specimen shape can deviate from an ideal hemisphere. Insufficient consideration of this aspect can introduce artifacts in the reconstructed dataset, ultimately degrading its spatial accuracy.

Quantification of area-selective deposition on nanometer-scale patterns using Rutherford backscattering spectrometry.

We present a site-specific elemental analysis of nano-scale patterns whereby the data acquisition is based on Rutherford backscattering spectrometry (RBS). The analysis builds on probing a large ensemble of identical nanostructures. This ensures that a very good limit of detection can be achieved.

Field dependent study on the impact of co-evaporated multihits and ion pile-up for the apparent stoichiometric quantification of GaN and AlN.

For atom probe tomography, multihits and any associated ion pile-up are viewed as an "Achilles" heel when trying to establish accurate stoichiometric quantification. A significant reason for multihits and ion pile-up is credited to co-evaporation events. The impact is the underestimation of one or more elements present due to detector inadequacies when the field evaporated ions are spatially and temporally close.

A Bottom-Up Volume Reconstruction Method for Atom Probe Tomography.

This paper describes a reconstruction method for atom probe tomography based on a bottom-up approach accounting for (i) the final tip morphology (which is frequently induced by inhomogeneous evaporation probabilities across the tip surface due to laser absorption, heat diffusion effects, and inhomogeneous material properties), (ii) the limited (and changing) field of view, and (iii) the detector efficiency. The reconstruction starts from the final tip morphology and reverses the evaporation sequence through the pseudo-deposition of defined small reconstruction volumes, which are then stacked together to create the full three-dimensional (3D) tip. The subdivision in small reconstruction volumes allows the scheme to account for the changing tip shape and field of view as evaporation proceeds.

Linearized radially polarized light for improved precision in strain measurements using micro-Raman spectroscopy.

Strain engineering in semiconductor transistor devices has become vital in the semiconductor industry due to the ever-increasing need for performance enhancement at the nanoscale. Raman spectroscopy is a non-invasive measurement technique with high sensitivity to mechanical stress that does not require any special sample preparation procedures in comparison to characterization involving transmission electron microscopy (TEM), making it suitable for inline strain measurement in the semiconductor industry. Indeed, at present, strain measurements using Raman spectroscopy are already routinely carried out in semiconductor devices as it is cost effective, fast and non-destructive.

Grain-boundary segregation of magnesium in doped cuprous oxide and impact on electrical transport properties.

In this study, we report the segregation of magnesium in the grain boundaries of magnesium-doped cuprous oxide (CuO:Mg) thin films as revealed by atom probe tomography and the consequences of the dopant presence on the temperature-dependent Hall effect properties. The incorporation of magnesium as a divalent cation was achieved by aerosol-assisted metal organic chemical vapour deposition, followed by thermal treatments under oxidizing conditions. We observe that, in comparison with intrinsic cuprous oxide, the electronic transport is improved in CuO:Mg with a reduction of resistivity to 13.

The impact of focused ion beam induced damage on scanning spreading resistance microscopy measurements.

Scanning Spreading Resistance Microscopy is a well-established technique for obtaining quantitative two- and three-dimensional carrier profiles in semiconductor devices with sub-nm spatial resolution. However, for sub-100 nm devices, the use of focused ion beam becomes inevitable for exposing the region of interest on a sample cross section. In this work, we investigate the impact of the focused ion beam milling on spreading resistance analysis and we show that the electrical effect of the focused ion beam extends far beyond the amorphous region and depends on the dopant concentration, ion beam energy, impact angle, and current density.

A Correlative ToF-SIMS/SPM Methodology for Probing 3D Devices.

With the continuous miniaturization and increasing complexity of the devices used in nanotechnology, there is a pressing need for characterization techniques with nm-scale 3D-spatial resolution. Unfortunately, techniques like Secondary Ion Mass Spectrometry (SIMS) fail to reach the required lateral resolution. For this reason, new concepts and approaches, including the combination of different complementary techniques, have been developed in over the past years to try to overcome some of the challenges.

Unravelling stacking order in epitaxial bilayer MX using 4D-STEM with unsupervised learning.

Following an extensive investigation of various monolayer transition metal dichalcogenides (MX), research interest has expanded to include multilayer systems. In bilayer MX, the stacking order strongly impacts the local band structure as it dictates the local confinement and symmetry. Determination of stacking order in multilayer MX domains usually relies on prior knowledge of in-plane orientations of constituent layers.

Size-dependent optical properties of periodic arrays of semiconducting nanolines.

We study the size-dependent optical properties of periodic arrays of semiconducting nanolines in the near-infrared to near-ultraviolet spectral range, where the absorption of the semiconductor increases. Using band structure calculations, we demonstrate that specific dimensions allow the slow down of the light, resulting in an enhanced absorption as compared to bulk material once the extinction coefficient of the semiconductor becomes comparable to its refractive index. Further, the refractive properties of the arrays can be tailored beyond the values of the constituting materials when the extinction coefficient of the semiconductor exceeds its refractive index.

Potential sources of compositional inaccuracy in the atom probe tomography of InGaAs.

With the objective of applying laser-assisted atom probe tomography to compositional analysis within nanoscale InGaAs devices, experimental conditions that may provide an accurate composition estimate were sought by extensively studying an InGaAs blanket film. Overall, the determined arsenic atomic fraction was found to exhibit an electric field dependent deficiency, which was more pronounced at low field conditions. Although the determined group III site-fraction also showed a (weak) field-dependent deficiency at low field conditions, it remained invariant with analysis conditions and in close agreement with the nominal value at higher field.

Application of electron channeling contrast imaging to 3D semiconductor structures through proper detector configurations.

Nowadays electron channeling contrast imaging (ECCI) is widely used to characterize crystalline defects on blanket semiconductors. Its further application in the semiconductor industry is however challenged by the emerging rise of nanoscale 3D heterostructures. In this study, an angular multi-segment detector is utilized in backscatter geometry to investigate the application of ECCI to the defect analysis of 3D semiconductor structures such as III/V nano-ridges.

Enhancing the defect contrast in ECCI through angular filtering of BSEs.

In this study, an annular multi-segment backscattered electron (BSE) detector is used in back scatter geometry to investigate the influence of the angular distribution of BSE on the crystalline defect contrast in electron channeling contrast imaging (ECCI). The study is carried out on GaAs and Ge layers epitaxially grown on top of silicon (Si) substrates, respectively. The influence of the BSE detection angle and landing energy are studied to identify the optimal ECCI conditions.

Atom probe of GaN/AlGaN heterostructures: The role of electric field, sample crystallography and laser excitation on quantification.

Scaling and non-planar architectures are key factors helping to advance the semiconductor field. Accurate 3-dimensional atomic scale information is therefore sought but this presents a significant metrology challenge. Atom probe tomography has emerged as a strong candidate to fulfill this role, but before it can be considered an accurate and precise metrology method, numerous difficulties need to be overcome.

Carrier profiling with fast Fourier transform scanning spreading resistance microscopy: A case study for Ge, GaAs, InGaAs, and InP.

Quantitative scanning spreading resistance microscopy is currently a powerful method for carrier profiling in scaled nanoelectronic devices. Faced with the further reduction of dimensions and increasing architecture complexity, a force modulation method was developed to address the challenges associated with parasitic series resistances. Called fast Fourier transform scanning spreading resistance microscopy, the method has been shown to increase dynamic range when profiling Si devices and retains the doping contrast even in the presence of a series resistance.

Effects of buried grain boundaries in multilayer MoS.

Two-dimensional transition metal dichalcogenides have been the focus of intense research for their potential application in novel electronic and optoelectronic devices. However, growth of large area two-dimensional transition metal dichalcogenides invariably leads to the formation of grain boundaries that can significantly degrade electrical transport by forming large electrostatic barriers. It is therefore critical to understand their effect on the electronic properties of two-dimensional semiconductors.

Chemical vapor deposition of monolayer-thin WS crystals from the WF and HS precursors at low deposition temperature.

Monolayer-thin WS with (0002) texture grows by chemical vapor deposition (CVD) from gas-phase precursors WF and HS at a deposition temperature of 450 °C on 300 mm Si wafers covered with an amorphous AlO starting surface. We investigate the growth and nucleation mechanism during the CVD process by analyzing the morphology of the WS crystals. The CVD process consists of two distinct growth regimes.

Laser-Induced Periodic Surface Structures (LIPSS) on Heavily Boron-Doped Diamond for Electrode Applications.

Diamond is known as a promising electrode material in the fields of cell stimulation, energy storage (e.g., supercapacitors), (bio)sensing, catalysis, etc.

Revealing the 3-dimensional shape of atom probe tips by atomic force microscopy.

For the very first time, atomic force microscopy is used to determine quantitatively the 3-dimensional shape of an atom probe tip, which is key towards improved accuracy and understanding of artefacts in atom probe tomography. We have successfully measured by atomic force microscopy the apex and shank region of 3 different atom probe tips, of which two show (severe) deviations from a hemisphere due to either non-uniform laser light absorption or the presence of two different materials. Clearly, our method which overcomes the challenge of aligning two very sharp tips on top of each other, offers new pathways to study physical mechanisms in (laser-assisted) atom probe.

Layer-controlled epitaxy of 2D semiconductors: bridging nanoscale phenomena to wafer-scale uniformity.

The rapid cadence of MOSFET scaling is stimulating the development of new technologies and accelerating the introduction of new semiconducting materials as silicon alternative. In this context, 2D materials with a unique layered structure have attracted tremendous interest in recent years, mainly motivated by their ultra-thin body nature and unique optoelectronic and mechanical properties. The development of scalable synthesis techniques is obviously a fundamental step towards the development of a manufacturable technology.

Electrical characterization of single nanometer-wide Si fins in dense arrays.

This paper demonstrates the development of a methodology using the micro four-point probe (μ4PP) technique to electrically characterize single nanometer-wide fins arranged in dense arrays. We show that through the concept of carefully controlling the electrical contact formation process, the electrical measurement can be confined to one individual fin although the used measurement electrodes physically contact more than one fin. We demonstrate that we can precisely measure the resistance of individual ca.

Nanoscale electrochemical response of lithium-ion cathodes: a combined study using C-AFM and SIMS.

The continuous demand for improved performance in energy storage is driving the evolution of Li-ion battery technology toward emerging battery architectures such as 3D all-solid-state microbatteries (ASB). Being based on solid-state ionic processes in thin films, these new energy storage devices require adequate materials analysis techniques to study ionic and electronic phenomena. This is key to facilitate their commercial introduction.

The flexoelectric effect in Al-doped hafnium oxide.

After the successful introduction as a replacement for the SiO2 gate dielectric in metal-oxide-semiconductor field-effect transistors, HfO2 is currently one of the most studied binary oxide systems with ubiquitous applications in nanoelectronics. For years, the interest of microelectronic downscaling has focused on tuning the dielectric constant of HfO2, particularly for monoclinic and tetragonal phases. Recently, Müller et al.

Influence of the Chalcogen Element on the Filament Stability in CuIn(Te,Se,S)/AlO Filamentary Switching Devices.

In this paper, we report on the use of CuInX (X = Te, Se, S) as a cation supply layer in filamentary switching applications. Being used as absorber layers in solar cells, we take advantage of the reported Cu ionic conductivity of these materials to investigate the effect of the chalcogen element on filament stability. In situ X-ray diffraction showed material stability attractive for back-end-of-line in semiconductor industry.