Atom probe tomography was employed to observe and derive the composition of carbon clusters in implanted silicon. This value, which is of interest to the microelectronic industry when considering ion implantation defects, was estimated not to exceed 2 at%. This measurement has been done by fitting the distribution of first nearest neighbor distances between monoatomic carbon ions (C+ and C2+). Carbon quantification has been considerably improved through the detection of molecular ions, using lower electric field conditions as well as equal proportions of 12C and 13C. In these conditions and using another quantification method, we have shown that the carbon content in clusters approaches 50 at%. This result very likely indicates that clusters are nuclei of the SiC phase.

The composition of GaAs measured by laser-assisted atom probe tomography may be inaccurate depending on the experimental conditions. In this work, we assess the role of the DC field and the impinging laser energy on such compositional bias. The DC field is found to have a major influence, while the laser energy has a weaker one within the range of parameters explored. The atomic fraction of Ga may vary from 0.55 at low-field conditions to 0.35 at high field. These results have been interpreted in terms of preferential evaporation of Ga at high field. The deficit of As is most likely explained by the formation of neutral As complexes either by direct ejection from the tip surface or upon the dissociation of large clusters. The study of multiple detection events supports this interpretation.

Accuracy of atom probe tomography measurements is strongly degraded by the presence of phases that have different evaporation fields. In particular, when there are perpendicular interfaces to the tip axis in the specimen, layers thicknesses are systematically biased and the resolution is degraded near the interfaces. Based on an analytical model of field evaporated emitter end-form, a new algorithm dedicated to the 3D reconstruction of multilayered samples was developed. Simulations of field evaporation of bilayer were performed to evaluate the effectiveness of the new algorithm. Compared to the standard state-of-the-art reconstruction methods, the present approach provides much more accurate analyzed volume, and the resolution is clearly improved near the interface. The ability of the algorithm to handle experimental data was also demonstrated. It is shown that the standard algorithm applied to the same data can commit an error on the layers thicknesses up to a factor 2. This new method is not constrained by the classical hemispherical specimen shape assumption.

The damage and ion distribution induced in Si by an inductively coupled plasma Xe focused ion beam was investigated by atom probe tomography. By using predefined patterns it was possible to prepare the atom probe tips with a sub 50 nm end radius in the ion beam microscope. The atom probe reconstruction shows good agreement with simulated implantation profiles and interplanar distances extracted from spatial distribution maps. The elemental profiles of O and C indicate co-implantation during the milling process. The presence of small disc-shaped Xe clusters are also found in the three-dimensional reconstruction. These are attributed to the presence of Xe nanocrystals or bubbles that open during the evaporation process. The expected accumulated dose points to a loss of >95% of the Xe during analysis, which escapes undetected.

An alternative approach for simulating the field evaporation process in atom probe tomography is presented. The model uses the electrostatic Robin’s equation to directly calculate charge distribution over the tip apex conducting surface, without the need for a supporting mesh. The partial ionization state of the surface atoms is at the core of the method. Indeed, each surface atom is considered as a point charge, which is representative of its evaporation probability. The computational efficiency is ensured by an adapted version of the Barnes–Hut N-body problem algorithm. Standard desorption maps for cubic structures are presented in order to demonstrate the effectiveness of the method.

The role of laser assisted atom probe tomography (APT) in microelectronics is discussed on the basis of various illustrations related to SiGe epitaxial layers, bipolar transistors or MOS nano-devices including gate all around (GAA) devices that were carried out at the Groupe de Physique des Matériaux of Rouen (France). 3D maps as provided by APT reveal the atomic-scale distribution of dopants and nanostructural features that are vital for nanoelectronics. Because of trajectory aberrations, APT images are subjected to distortions and local composition at the nm scale may either be biased. Procedures accounting for these effects were applied so that to correct images.

With the ability to locate and identify atoms in three dimensions, atom-probe tomography (APT) has revolutionized our understanding of structure-property relationships in materials used for structural applications. The atomic-scale details of clusters, second phases, and microstructural defects that control alloy properties have been investigated, providing an unprecedented level of detail on the origins of aging behavior, strength, creep, fracture toughness, corrosion, and irradiation resistance. Moreover, atomic-scale microscopy combined with atomistic simulation and theoretical modeling of material behavior can guide new alloy design. In this article, selected examples highlight how APT has led to a deeper understanding of materials structures and therefore properties, starting with the phase transformations controlling the aging and strengthening behavior of complex Al-, Fe-, and Ni-based alloys systems. The chemistry of interfaces and structural defects that play a crucial role in high-temperature strengthening, fracture, and corrosion resistance are also discussed, with particular reference to Zr- and Al-alloys and FeAl intermetallics.

Nanostructural features of nickel-base superalloys as revealed by atom probe field ion microscopy (APFIM) and atom probe tomography (APT) are reviewed. The more salient information provided by these techniques is discussed through an almost exhaustive analysis of literature over the last 30 years. Atom probe techniques are shown to be able to measure the composition of tiny γ′ precipitates, a few nanometers in size, and to reveal chemical order within these precipitates. Phase separation kinetics in model NiCrAl alloys was investigated with both 3DAP and Monte-Carlo simulation. Results are shown to be in good agreement. Plane by plane analysis of {001} planes of Ni3Al-type γ′ phase makes it possible to estimate the degree of order as well as the preferential sites of various addition elements (Ti, Cr, Co, W, Ta, Re, Ru, etc.) included in superalloys. Clustering effects of Re in the γ solid solution were also exhibited. Due to its ultrahigh depth resolution, the microchemistry of interfaces and grain boundaries can be characterized on an atomic scale. Grain boundaries in Astroloy or N18 superalloys were found to be enriched in B, Mo, and Cr and Al depleted.

A Mo-rich precipitate in an Fe-rich matrix and the heterophase interface bounding the precipitate have been examined on an atomic scale by three-dimensional atom-probe (3DAP) microscopy and transmission electron microscopy (TEM). The Mo-rich precipitate was generated by isothermal solid-state decomposition at 500°C of an Fe-15 at.% Mo-5 at.% V alloy. After this heat treatment, TEM reveals a characteristic modulated strain contrast structure. The precipitate has a composition of Mo-13.0 at.% Fe-4.9 at.% V as measured by 3DAP microscopy. The alloy decomposes at a nearly constant 5 at.% V, constituting a metastable tie-line between Fe-rich and Mo-rich bcc solid solutions. The formation of the equilibrium intermetallic phases is kinetically impeded. A local vanadium enrichment of 21 at.% is detected at the interface of the precipitate in a matrix region about 0.27 nm or 1–2 atomic layers in thickness. The corresponding value of the Gibbsian interfacial excess of vanadium is 3.3 ± 1.3 nm−2.

Intermetallic alloys are often doped with boron to suppress their intrinsic room-temperature intergranular brittleness. The commonly admitted mechanism of this effect, i.e. an intergranular segregation of boron, seems not to be the only important feature. In this work, boron interactions with numerous kinds of crystal defects (point defects, dislocations, grain boundaries) are studied in B-doped FeAl (B2) alloys containing 40 at. % Al. The intergranular segregation of boron is first characterized. Both an equilibrium and a non-equilibrium (due to a solute atom / thermal vacancy interaction) segregation mechanisms are identified. Strong tendency of boron to segregate to the dislocations lines is shown by direct measurements by atom probe field ion microscopy (AP FIM). This segregation is shown to induce a local depletion in Al in the vicinity of defects.

The emergence of the field ion microscope, invented by E.W. Müller in 1951, allowed, for the first time, direct observation of metallic materials in real space on an atomic scale. Field ionization of rare gas atoms near the surface of the material allowed production of an atomic resolution image of the material; field evaporation of surface atoms allowed observation into the depth of the sample.

Field ion microscopy (FIM) has produced numerous impressive results, one of them being three-dimensional reconstruction of defect cascades produced by heavy ion irradiation in metals. FIM techniques have also contributed in a spectacular way to the knowledge of the crystallographic structure of grain boundaries. Surface diffusion as well as surface reconstruction phenomena are applications where, again, FIM gave surprisingly detailed information. This overview of applications of FIM in materials science emphasizes recent work. Detailed information and descriptions of earlier work can be found elsewhere.

During the development of FIM techniques, the basic shortcomings of the instrument for investigating metallic alloys were rapidly recognized. In Cu3Pd alloys, for instance, Cu atoms are darkly imaged and therefore appear as vacancies similar to Co atoms in PtCo and Pt3Co. It is thus impossible to distinguish vacancies from solute atoms. This clearly limited the quantitative use of FIM to study short-range

order in dilute alloys or to investigate long-range order (Figure 1). Similarly, in two-phase materials, precipitates often give rise to quite visible contrast. For instance, in nickel-based alloys, aluminum-enriched precipitates appear in bright contrast. It is therefore possible to find the size and also the number density of particles present in the material. However, FIM does not provide any composition data.