Accurate quantification of n-type dopant, such as phosphorus (P) and arsenic (As) in silicon-germanium (SiGe), is critical for source/drain engineering, junction control, and device variability in advanced complementary metal-oxide-semiconductor. Especially for As in SiGe, conventional microanalysis techniques, such as transmission electron microscopy combined with energy dispersive x-ray spectroscopy or electron energy loss spectroscopy, struggle at technologically relevant doping levels and suffer from peak-overlap issues for As in the presence of Ge. Common secondary ion mass spectrometry (SIMS) platforms, such as magnetic sector (MS), quadrupole (Quad), and time-of-flight (ToF), face severe mass interferences at limited mass resolving power as well as low ion yields. Here, we translate the Orbitrap (TM)-SIMS workflow, previously validated for P in Si/SiGe, to As in SiGe, combine it with self-focusing SIMS (SF-SIMS) for patterned features, and benchmark Orbitrap (TM)-SIMS against ToF-SIMS, Quad-SIMS, and MS-SIMS. Using blanket Si1-xGex standards and patterned Ge1-y-zSiySnz:As fins, we show that the exceptional mass resolving power of the Orbitrap (TM) mass analyzer eliminates the dominant As interferences (e.g., As- vs GeH-; AsSi- vs GeSiH-/(SiGe-)-Si-29/(SiGe-)-Si-30-Ge-73; and AsGe- vs (GeGe-)-Ge-73-Ge-76/Ge2H-) and detection limits improve by >1 order of magnitude versus ToF-SIMS and MS-SIMS when SF-relevant clusters are used. As a result, only Orbitrap (TM)-SIMS recovers the physically correct "top-only" As-doped segment in Ge1-y-zSiySnz fins, whereas other mass analyzers erroneously report As throughout the fin due to unresolved overlaps and high backgrounds. These results are confirmed by fast Fourier transform-scanning spreading resistance microscopy 2D carrier distribution mapping.

The continuous downscaling of semiconductor devices has created a pressing need for analytical methodologies capable of enabling process control in confined volumes and sub-100 nm features. Conventional secondary ion mass spectrometry (SIMS), while highly sensitive, lacks the spatial resolution required for such applications. Nevertheless, SIMS remains a powerful tool for the analysis of small features through the self-focusing (SF) SIMS concept, which exploits the formation of cluster ions that inherently localize chemical information within the region of interest. In this study, SF-SIMS is applied to the quantification of boron in patterned samples composed of boron-doped silicon fins with widths ranging from 500 to 20 nm, embedded in boron-doped silicon oxide. By selecting cluster ions that originate exclusively from the silicon fin region, the spatial resolution limitations of conventional SIMS are overcome without compromising the sensitivity. Using this approach, a boron implant with a peak concentration of ∼9 × 1020 at/cm3 was measured in the widest fins (500 nm), in good agreement with SRIM simulations and conventional SIMS methods, while a concentration of ∼4.5 × 1020 at/cm3 was obtained for the narrowest fins (20 nm). This study establishes SF-SIMS as a reliable, rapid, and preparation-free approach for dopant quantification in nanoscale semiconductor devices down to 20 nm.

High-efficiency silicon (Si) heterojunction (SHJ) solar cell technology is currently limited by multi-step fabrication protocol required for optimal passivation and carrier selectivity. Here, a novel, one-step oblique-angle reactive sputtering strategy is presented that leverages angle-dependent ion-bombardment to simultaneously tailor the bulk and interfacial properties of metal oxide contact material on Si via in situ ion assisted oxidation. Using vanadium oxide (V2O5-x) as a model system, it has been demonstrated that the deposition at a glancing angle of 80° yields a phase-pure, high-work-function V2O5-x film-essential for field effect passivation, while also facilitating stoichiometric improvement of the retained native silicon oxide layer on Si surface. An intermediate growth angle of 40°, produces a mixed-phase V2O5-x film, without compromising interfacial quality. Monte Carlo simulations, supported by time-of-flight secondary ion mass spectrometry data, reveal that growth angle governs the V-Si-O intermixing depth across the interface through variations in ion incidence geometry and energy deposition profile, critically influencing the interfacial layer properties. This simple, one-step, room temperature, angle-tuned reactive sputtering method circumvents multi-step chemical pre-treatments of the silicon surface and offers a viable pathway for integrating carrier selective metal oxides in SHJ solar cells, with broader applicability across silicon-based electronic and optoelectronic devices.

Ru post dry-etch surfaces are exposed to UV irradiation and subsequent wet cleaning, to remove post etch residues. The nature of these residues, their removal efficiency and mechanisms are investigated. The post etch surface consists of native oxides of Ru and Ti along with Cl-impurities. Both UV and UV + wet cleaning processes are found to reduce the native oxide and Cl-residues, increase the hydrophilicity of the surface and improve the residue removal efficiency by improving the wetting of the small trenches (9 nm CD) in the patterned structures (18 nm metal pitch). Leakage measurements show an improvement in the leakage yield from similar to 30% to similar to 50% at a current of 1x10(-11) A.

Time of Flight Secondary Ion Mass Spectrometry is a powerful technique for the characterization of various materials. Depth profiling in the dual beam mode enables the acquisition of information about the threedimensional composition of a sample. In this context, the selection of the most appropriate sputter conditions is of critical importance in order to ensure the reliability of the results obtained. Despite advancements, challenges persist in finding a suitable sputter source to perform depth profiling on hybrid nanomaterials (based on the mixing of pure organic and inorganic compounds), primarily due to the different sputtering conditions required for the inorganic and the organic components. In this work, we present an approach that employs a high-energy-per-atom argon cluster sputter source to perform depth profiling of a model hybrid sample consisting of molybdenum oxide and N,N '-Di(1-naphthyl)-N,N '-diphenyl-(1,1 '-biphenyl)-4,4 '-diamine. The findings demonstrated that decreasing the cluster size while maintaining a high kinetic energy of the beam allowed to increase the sputtering yield for the inorganic moiety, while preserving the molecular information of the organic counterpart. Moreover, we demonstrated that damage accumulation and ion beam mixing processes can be successfully attenuated by decreasing the sample temperature during depth profiling.

Due to their unique properties, two-dimensional transition metal dichalcogenides (2D TMDCs) are considered for diverse applications in microelectronics, sensing, catalysis, to name a few. A common challenge in 2D TMDC research is the film's inherent instability i.e. spontaneous oxidation upon ambient exposure. The present study systematically explores the effect aging on the film composition and photoluminescent properties of monolayer WS2, synthetically grown by metal-organic chemical vapor deposition. The aging rate is investigated for different oxygen- (i.e. O-2 gas concentration and humidity) and light-controlled environments. Simple mitigation strategies that do not involve capping the 2D TMDC layer are discussed, and their effectiveness demonstrated by benchmarking the evolution in photoluminescence response against ambient exposed monolayer WS2. These results highlight the need to store 2D TMDCs in controlled environments to preserve the film quality and how future studies can account for the aging effect.

OrbiSIMS is a secondary ion mass spectrometry method with dual mass analyzers: a time-of-flight (ToF) mass spectrometer for high-speed imaging and an Orbitrap™ for high mass resolving power and mass accuracy. Originally developed for biological imaging, there is now growing interest in the application to semiconductor materials to resolve peak interferences that obfuscate analysis in traditional SIMS depth profiling experiments. We use a new method to calibrate the Orbitrap intensity scale to true counts, which allows comparison of the useful yield and duty cycle with a magnetic sector instrument and a time-of-flight instrument using an Sb implant in the silicon sample. The useful yield of the Orbitrap and magnetic sector instruments (for one detected peak) are similar. However, since the magnetic sector instrument has serial mass detection, its useful yield reduces as more peaks are analyzed. While the ToF instrument has parallel detection, it has a low duty cycle and the useful yield is two orders of magnitude lower for 1000 eV Cs+ sputtering. The depth resolution was also compared from the measurement of the downslope from depth profiles of an Sb delta multilayer. For 1000 eV Cs+ sputtering, the downslopes are 3.9, 2.3, and 2.7 nm/decade for Orbitrap, magnetic sector, and ToF instruments, respectively. Ion trajectory simulation shows that the poorer depth resolution of the OrbiSIMS is in part due to ion beam distortion at low energy.

Abstract Imec has developed a fully-functional integrated forksheet field-effect transistors (FETs), which is the most promising architecture for advancing beyond the GAA (Gate-All-Around) nanosheet generation for scaling and performance improvements past the 2nm technology node. From a manufacturing perspective, forksheet devices are extremely complex to process and requires accurate and sensitive analytical instruments like the AKONIS SIMS tool.

Atomically thin, 2D semiconductors, such as transition metal dichalcogenides, complement silicon in ultra-scaled nano-electronic devices. However, the semiconductor and its interfaces become increasingly more difficult to characterize chemically and electrically. Conventional methodologies, including scanning probe microscopies, fail to capture insight into the chemical and electronic nature of the semiconductor, albeit vital to understand its impact on the semiconductor performance. Therefore, this work presents a unique and universal in situ approach combining time-of-flight secondary ion mass spectrometry and atomic force microscopy to map chemical differences between regions of different electrical conductivity in epitaxially deposited tungsten disulfide (WS2) on sapphire substrates. Surprisingly, WS2 regions of lower electrical conductivity possess a larger amount of sulfur compared to regions with higher conductivity, for which oxygen is also detected. Such difference in chemical composition likely roots from the non-homogeneously terminated sapphire starting surface, altering the WS2 nucleation behavior and associated defect formation between neighboring sapphire terraces. These resulting sapphire terrace-dependent doping effects in the WS2 hamper its electrical conductivity. Thus, accurate chemical assignment at a sub-micrometer lateral resolution of atomically thin 2D semiconductors is vital to achieve a more detailed understanding on how the growth behavior affects the electrical properties.

Due to the extremely high specific surface area of nanoparticles and corresponding potential for adsorption, the results of surface analysis can be highly dependent on the history of the particles, particularly regarding sample preparation and storage. The sample preparation method has, therefore, the potential to have a significant influence on the results. This report describes an interlaboratory comparison (ILC) with the aim of assessing which sample preparation methods for ToF-SIMS analysis of nanoparticles provided the most intra- and interlaboratory consistency and the least amount of sample contamination. The BAM reference material BAM-P110 (TiO2 nanoparticles with a mean Feret diameter of 19 nm) was used as a sample representing typical nanoparticles. A total of 11 participants returned ToF-SIMS data, in positive and (optionally) negative polarity, using sample preparation methods of "stick-and-go" as well as optionally "drop-dry" and "spin-coat." The results showed that the largest sources of variation within the entire data set were caused by adventitious hydrocarbon contamination or insufficient sample coverage, with the spin-coating protocol applied in this ILC showing a tendency toward insufficient sample coverage; the sample preparation method or the participant had a lesser influence on results.

The complexity of the water adsorption-desorptionmechanismat the interface of transition metal dichalcogenides (TMDs) and itsimpact on their current transport are not yet fully understood. Here,our work investigates the swift intercalation of atmospheric adsorbatesat the TMD and sapphire interface and between two TMD monolayers andprobes its influence on their electrical properties. The adsorbatesconsist mainly of hydroxyl-based (OH) species in the subsurface regionsuggesting persistent water intercalation even under vacuum conditions,as determined by time-of-flight-secondary ion mass spectrometry(ToF-SIMS) and scanning tunneling microscopy (STM). Water intercalatesthere rapidly, within the order of a few minutes after being exposedto ambient atmosphere, this process tends to be partly reversibleunder (ultra)-high vacuum, as observed by time-dependent scanning probemicroscopy (SPM) based conductivity and ToF-SIMS measurements. A significantenhancement of the electronic properties is observed with the completedesorption of intercalated water clusters because of the pressure-inducedmelting effect under the tip of the SPM probe. Conversely, it alsoindicates that the characterization of TMD samples is substantiallyaffected in air, in inert environments, and to some extent even ina vacuum if water intercalation is present. More importantly, STManalysis has uncovered a correlation between water intercalation andthe presence of defects, showcasing their role in the gradual degradationof the material as it ages.

This study reports on the application of secondary ion mass spectrometry (SIMS) for examining thin (20-50 nm) chemically amplified resist films on silicon. SIMS depth profiling was carried out using a gas cluster ion beam to ensure minimal sputter-induced damage to the organic constituents of interest. Specific attention concerned the distribution of the photo acid generator (PAG) molecule within these films, along with the photo-induced fragmentation occurring on extreme ultra-violet photo exposure. Positive secondary ion spectra were collected using a traditional time of flight (ToF)-SIMS and the latest generation IONTOF Hybrid SIMS instrumentation equipped with an OrbitrapTM mass analyzer. Tandem mass spectrometry (MS/MS) capability within the OrbitrapTM secondary ion column was utilized to verify that the C19H17S+ secondary ion did indeed have the molecular structure consistent with the PAG structure. The superior mass resolving power of the OrbitrapTM mass analyzer (∼20× of the ToF mass analyzer) along with improved mass accuracy (a few ppm) proved pivotal in the mass spectral and depth profile analysis of these films. This was not the case for the ToF-SIMS experiments, as the mass spectra, as well as the associated depth profiles, exhibited severe molecular (isobaric) interferences.

Shrinking semiconductor device dimensions requires extensive R&D in all areas, inclusive of the materials characterization techniques and methodologies commonly used. With dimensions now being much smaller than the beam spot sizes of usual characterization methods like SIMS, RBS, etc., new concepts are needed. In this context, the application of Self-Focusing SIMS (SF-SIMS) to determine the bulk composition of structures of exceedingly small dimensions was demonstrated in the past years. However, due to the extensive use of secondary ions of higher m/z in the SF-SIMS concept, high mass resolution is often required; this is to avoid possible mass interferences that limit the SF-SIMS method to reach low detection limits and/or to unambiguously identify the ion signals. Although the mass resolving power of Time-of-Flight (ToF) analyzers of SIMS instruments is considered high (m/Delta m -10000), it still presents a restriction for the SF-SIMS methodology on specific systems. The OrbitrapTM mass analyzer allows an increase in the mass resolution up -20x along with mass accuracy levels below one ppm. In this study, we demonstrate that the mass resolving power of the OrbitrapTM-SIMS allows to resolve limiting mass interferences, thereby allowing accurate quantification of impurities/dopants in small finFET structures (<20 nm).

Intercalation mechanisms and diffusion or segregation phenomena in graphitic materials play a crucial role in different applied science fields. The investigation of such phenomena is usually accomplished through depth profiling experiments. Ar-GCIBs (Argon- Gas Cluster Ion Beams) are commonly adopted for in-depth concentration profiling of organic or soft materials; on the other hand, cesium ions are in general more suitable for the sputtering of inorganics. During such experiments, the beam-target interaction could alter chemistry and structure of the material. In this work, we define the optimal conditions in terms of both sputtering ion source and energy to preserve the crystal features. HOPG was used as a model system to compare morphological, physical, and chemical effects induced by different Ar-n(+) clusters, and ultra-low energy Cs+ beam during ToF-SIMS (Time of Flight Secondary Ion Mass Spectrometry) depth profiling experiments. We demonstrated, through in-situ AFM (Atomic Force Microscopy) analysis, that the monoatomic Cs+ beam alters to a lower extent the HOPG structure. On the contrary, Ar-GCIBs strongly modify the graphite surface basal plane and underlying layers. However, HOPG crystals treated with the cesium monoatomic source undergo a chemistry modification leading to the formation of graphite oxide (GOx) together with the presence of hydrogen, and cesium adducts.

Heavily P-doped epitaxial Si layers were deposited over counter-doped Si substrates. P dopant activation was studied as a function of various processes used to prepare the samples. For electrical characterization, depth profiles of carrier concentration values were obtained using SSRM and DHEM techniques. Samples studied included an in-situ doped sample, a sample that was spike annealed at 1000ºC, a sample that was first coated with a Ti/TiN stack and then annealed for silicide formation before the Ti/TiN stack was removed, and a sample that was spike annealed + coated with Ti/TiN + annealed for silicide formation before the removal of the Ti/TiN stack. DHEM analysis showed substantial increase in dopant activation for spike annealed samples. SSRM results suggested lower carrier concentration values and more limited degree of activation. Formation of Ti/TiN contacts and its removal did not affect the carrier concentration values for the as-deposited epi layer. Sample that was first spike annealed and then subjected to contact formation process displaced a reduction in carrier concentration values as measured by DHEM.

The introduction of the 3D NAND architecture brought new integration challenges, including the impact of fabrication-induced mechanical stress. If not controlled, the mechanical stress can result in high wafer warpage, incompatible with wafer handling and lithography steps. This work presents a study of the impact of annealing on the warpage and residual stress of blanket SiO2/Si3N4 stacks relevant to 3D NAND fabrication. It is shown that annealing promotes H outgassing from the Si3N4 layers and minimizes their residual stress. The optimal temperature is calculated by combining the warpage measurements with finite element modelling. That allows to calibrate the model on simplified samples and then expand it for stacks with a higher number of layers, which can be beneficial for the future 3D NAND generations.

Atomic layer deposition (ALD) of ruthenium dioxide (RuO2) thin films using metalorganic precursors and O-2 can be challenging because the O-2 dose needs to be precisely tuned and significant nucleation delays are often observed. Here, we present a low-temperature ALD process for RuO2 combining the inorganic precursor ruthenium tetroxide (RuO4) with alcohols. The process exhibits immediate linear growth at 1 angstrom/cycle when methanol is used as a reactant at deposition temperatures in the range of 60-120 degrees C. When other alcohols are used, the growth per cycle increases with an increasing number of carbon atoms in the alcohol chain. Based on X-ray photoelectron spectroscopy (XPS) and conventional X-ray diffraction, the deposited material is thought to be amorphous RuO2. Interestingly, pair distribution function (PDF) analysis shows that a structural order exists up to 2-3 nm. Modeling of the PDF suggests the presence of Ru nanocrystallites within a predominantly amorphous RuO2 matrix. Thermal annealing to 420 degrees C in an inert atmosphere crystallizes the films into rutile RuO2. The films are conductive, as is evident from a resistivity value of 230 mu Omega.cm for a 20 nm film grown with methanol, and the resistivity decreased to 120 mu Omega.cm after crystallization. Finally, based on in situ mass spectrometry, in situ infrared spectroscopy, and in vacuo XPS studies, an ALD reaction mechanism is proposed, involving partial reduction of the RuO2 surface by the alcohol followed by reoxidation of the surface by RuO4 and concomitant deposition of RuO2.

The structural and electrical properties of Mo thin films with thicknesses between 3 and 50 nm, deposited by physical vapor deposition, have been evaluated in order to assess the potential of Mo as an alternative to Cu or W for nano-interconnect applications. Mo films deposited on SiO2/Si (100) were polycrystalline with randomly oriented grains close to the interface and the progressive formation of a (110) texture above 5 nm film thickness. Adhesion between Mo and low-kappa dielectrics was strong with adhesion energies above 5 J/m(2). The films showed intrinsic tensile stress of similar to 1 GPa, which decreased with increasing thickness. The Mo resistivity showed a weaker thickness dependence than Cu, which rendered Mo competitive with conventional TaN/Cu/TaN metallization below metal thicknesses of 8 nm. Semiclassical resistivity modeling found that the thin film resistivity was limited by grain boundary scattering with a reflection coefficient of R = 0.46 +/- 0.03. Furthermore, the effects of Mo deposition on different dielectric and metallic substrates and of post-deposition annealing up to 950 degrees C were investigated. Crystallinity, impurity concentration, and resistivity were all affected by the substrate. Post-deposition annealing in H-2 led to continuous grain growth, followed by recrystallization at 860 degrees C. Furthermore, annealing at 650 degrees C led to compressive stress in the films. By contrast, annealing in H-2/N-2 led to the incorporation of N and ultimately to Mo nitride formation above 500 degrees C. The results indicate that Mo can be a promising candidate for advanced interconnect metallization schemes if surface oxidation as well as impurity incorporation can be kept under control.

Research on carbon nanotube (CNT) films for the EUV pellicle application was initiated at imec in 2015 triggered by the remarkable optical, mechanical, and thermal properties of the CNT material. Today the advancement of the CNT material synthesis together with matured methods to fabricate thin CNT membranes make free-standing CNT films a very promising EUV pellicle candidate for high volume EUV lithography. Balancing the CNT material properties for the optimal pellicle performance in EUV scanners remains the ongoing research focus. Depending on the density and morphology of the CNTs within the film and individual CNT parameters, like number of walls, bundle size, metal catalyst content, purity etc., the optical and thermal properties of the CNT pellicle can be tuned. It is critical for the pellicle to be stable in the EUV lithography scanner environment which includes hydrogen plasma and heat loads associated with high powers beyond 250 W. Different types of CNTs, i.e. single-, double-, multi-walled CNTs and their combinations, are explored as building blocks of an optimized pellicle membrane. Optical properties of different pellicles and their ability to withstand high EUV powers in the hydrogen-based environment were tested. Transmission, spectroscopic and chemical composition mapping of the exposed free-standing CNT films are used to study the material changes that occur in the scanner-like environment. A solution is needed to extend the CNT pellicle lifetime and coating is discussed as a potential approach to protect the CNT material from hydrogen plasma damage.