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Volatile A-cation halide (AX) additives such as formamidinium chloride and methylammonium chloride have been widely employed for high-efficiency perovskite solar cells (PSCs). However, it remains unstudied how they influence the perovskite film stoichiometry and the solar cell performance and operational stability. Hereby, our work shows that over annealing of formamidinium chloride-containing perovskite films leads to a Pb-rich surface, resulting in a high initial efficiency, which however decays during maximum power point tracking (MPPT). On the contrary, perovskite films obtained by a shorter annealing time at the same temperature provide good stability during MPPT but a lower initial efficiency. Thus, we deduce that an optimal annealing is vital for both high efficiency and operational stability, which is then confirmed in the case where methylammonium chloride additive is used. With optimized perovskite annealing conditions, we demonstrate efficient and stable p-i-n PSCs that show a best power conversion efficiency of 20.7% and remain 90% of the initial performance after a 200 h MPPT at 60 °C under simulated 1 sun illumination with high UV content. Our work presents a comprehensive understanding on how volatile AX impacts perovskite film stoichiometry and its correlation to the device performance and operational stability, providing a new guideline for fabricating high-efficiency and operationally stable PSCs.

We propose a simple additive approach to simulate X-ray photoelectron spectra (XPS) of macromolecules based on the $GW$ method. Single-shot $GW$ ($G_0W_0$) is a promising technique to compute accurate core-electron binding energies (BEs). However, its application to large molecules is still unfeasible. To circumvent the computational cost of $G_0W_0$, we break the macromolecule into tractable building blocks, such as isolated monomers, and sum up the theoretical spectra of each component, weighted by their molar ratio. In this work, we provide a first proof of concept by applying the method to four test polymers and one copolymer, and show that it leads to an excellent agreement with experiments. The method could be used to retrieve the composition of unknown materials and study chemical reactions, by comparing the simulated spectra with experimental ones.

Volatile A-cation halide (AX) additives such as formamidinium chloride and methylammonium chloride have been widely employed for high-efficiency perovskite solar cells (PSCs). However, it remains unstudied how they influence the perovskite film stoichiometry and the solar cell performance and operational stability. Hereby, our work shows that over annealing of formamidinium chloride-containing perovskite films leads to a Pb-rich surface, resulting in a high initial efficiency, which however decays during maximum power point tracking (MPPT). On the contrary, perovskite films obtained by a shorter annealing time at the same temperature provide good stability during MPPT but a lower initial efficiency. Thus, we deduce that an optimal annealing is vital for both high efficiency and operational stability, which is then confirmed in the case where methylammonium chloride additive is used. With optimized perovskite annealing conditions, we demonstrate efficient and stable p–i–n PSCs that show a best power conversion efficiency of 20.7% and remain 90% of the initial performance after a 200 h MPPT at 60 °C under simulated 1 sun illumination with high UV content. Our work presents a comprehensive understanding on how volatile AX impacts perovskite film stoichiometry and its correlation to the device performance and operational stability, providing a new guideline for fabricating high-efficiency and operationally stable PSCs.

The steam oxidation of SiGe shows a transition from Si-like to Ge-like oxidation behavior depending on Ge concentration and oxidation temperature. Ge-like oxidation is described by the generation of oxygen vacancies (VO) at the interface between the oxide and SiGe virtual substrate. [1] Due to the different oxidation behavior, the presence of a Ge-oxide-free interfacial layer (IL) can suppress SiGe oxidation. [2] Here we show how a passivating interfacial layer can be grown using low-pressure oxidation and highlight the importance of SiGe surface preparation prior to low-pressure oxidation.

This article reports Si-passivated Ge nFinFETs with significantly improved GmSAT/SSSAT and positive bias temperature instability (PBTI) reliability enabled by an improved replacement metal gate (RMG) high- ${k}$ last process. SiO2 dummy gate oxide (DGO) deposition on Ge fin is shown to form (Si x )Ge1- x O y , which is, compared to a pure SiO2, more difficult to remove completely during the dry clean prior to the gate-stack formation. By extending the DGO removal clean, improved PBTI reliability, reduced ${D}_{{\text {IT}}}$ , and increased electron mobility are demonstrated. Moreover, by suppressing the Ge channel oxidation through the choice of less-oxidizing DGO or inserting an Si-cap layer prior to the DGO deposition, a greatly improved long-channel electron mobility is obtained at a scaled fin width. Finally, together with the PBTI maximum ${V}_{{\text {OV}}}$ of 0.13 V, the best GmSAT/SSSAT of 5.4 is achieved, which is today’s record value among the sub-100-nm- ${L}_{g}$ n-channel Ge Fin and gate-all-around nanowire FETs. These results clearly show the importance of the pre-gate-stack channel surface preparation on the scaled Ge FinFETs to benefit from a previously optimized Si-passivated Ge gate-stack.

Background: An extreme ultraviolet (EUV)-transparent pellicle must be used during lithography to protect the photomask from fall-on particles. A pellicle made of free-standing carbon nanotube (CNT) films stops particles despite the presence of gaps while demonstrating high EUV transmission, mechanical stability, low EUV scattering and reflectivity, and DUV transmission that enables through-pellicle mask inspection. Aim: The CNT EUV pellicle properties can be tailored based on the diversity of CNT structures and tunability of their configuration within the CNT film (density, bundle size, composition, etc.) as shown in this work. A remaining challenge is extending the CNT EUV pellicle lifetime in the scanner environment of EUV-induced hydrogen-based plasma, and the effects on different CNT films are explored here. Approach: Optical and thermal properties of different CNT pellicles with respect to the CNT material type, density, composition, and bundle size were explored. The ability of uncoated CNT EUV pellicles to withstand high EUV powers in the hydrogen-based environment was tested. Transmission, spectroscopic, and chemical mapping of the exposed CNT membranes were performed to explore the material modifications under various exposure conditions. Results: Uncoated CNT pellicles withstand 600-W source power equivalent in the EUV scanner-like gas environment but exhibit structural changes with prolonged exposure. Multiwalled CNT pellicles exhibit less EUV transmission change as compared to single-walled CNT pellicles under the same exposure conditions. The protection of CNT material from structural degradation by means of coating was shown. Conclusions: These investigations add to the understanding of CNT EUV pellicle tunability for optimal performance and lifetime limiters of CNT pellicles under the influence of EUV radiation and plasma. We anticipate the need for coating the CNT pellicle to protect the CNT material against plasma damage for the current scanner conditions. Optimization of both the CNT membrane and its coating is in progress.

In this study, we explored the key properties and functionalities of plasma enhanced atomic layer deposition (PEALD) SiNx films, synthesized using different deposition temperatures (500–550 °C) and plasma conditions (lower and higher), both on 300 mm blanket Si and on several integrated 3D topology substrates, at the thicknesses relevant for diverse nanoscale applications. Our study shows that with an increase of temperature (500–550 °C), a small reduction in HF wet etch rate (1.1–0.69 nm/min), and H content (9.6% vs 7.4%) was observed. When using higher plasmas, significant improvements in blanket properties were observed. The films were denser (2.95 g/cm3), exhibited lower H content (2.4%), showed better etch rates (0.39 and 0.44 nm/s for HF and CF4 based), and SiNx grew without any nucleation delay on alternative Si1−xGex channel surfaces. The vertical and lateral conformality was found to be similar and appears not to be impacted with the plasma conditions. Extensive steam oxidation barrier studies performed at the sidewalls of different aspect ratio lines showed the PEALD SiNx liner scaling potentiality down to 1 nm when deposited using higher plasma. In addition, the outer gate and inner spacer properties were found to be superior (with lower loses) for higher plasma films when subjected to several dry etch, strips, and H3PO4 chemistries. The outstanding conformality (90%–95% on aspect ratios ≤10:1) combined with excellent high end material properties in the ultrathin regimes (1–10 nm) corroborate the virtue of PEALD SiNx toward integration in scaled down and advanced nanoelectronics device manufacturing.

A key factor enabling the reduction of the thermal budget in W2W bonding integration flows is the activation sequence, consisting of cleaning and plasma treatment, used before bonding. For hybrid bonding such activation sequence needs to be selected to fulfill multiple functions: activation of the dielectric bonding surface to obtain a high bonding energy during room temperature bonding, minimize the dielectric bonding annealing temperature while avoiding exposed Cu oxidation and reducing the required annealing temperature for proper Cu-to-Cu bonding. In this paper we discuss the effect of different wafer clean methods (Deionized (DI) water and citric acid) and the effect of different plasma treatments on SiCN and Cu surfaces before bonding. The characterization techniques used include XPS, TEM, ellipsometry, SAM, OES and wafer-to-wafer bond strength testing. It is observed that Nitrogen plasma treatment can help in reducing the CuOx and a mild passivation effect of the surface is observed. Whereas on the Cu pads citric acid, used just before bonding, appears a good option, since clear effectiveness in reducing the CuOx is observed, on the dielectric it may leave some residues which can result sometimes in bonding defects. Moreover, a metric to evaluate efficient SiCN-SiCN bonding is proposed and further understanding of the physical mechanisms involved in SiCN-SiCN bonding are suggested.

Micro- and nano-electronics is increasingly relying on heterogeneous, confined and three-dimensional structures, to continue the downscaling required for the next technology generations. Area-selective atomic layer deposition (ALD) is one suited methodology to create nm-scale features through (1) the area-selective self-assembly of a blocking layer (i.e. a thiol deposited on copper) and (2) the ALD growth on the areas not covered with the blocking layer (i.e. a dielectric deposited on low-k). Assessing the efficiency and defectivity of selective deposition on such samples would require a lateral resolution much smaller than the feature size of interest. Hence the need for characterization techniques appropriate to the device’s dimensions. Recently, thanks to the Self-Focusing Secondary Ions Mass Spectrometry (SF-SIMS) concept, the SIMS applicability to analyze the composition of narrow (

Alkyl-terminated surfaces have received significant interest as growth-blocking surfaces in area-selective deposition (ASD). Gas-phase chemical functionalization is attractive in this context due to its short process times, potentially wide applicability, and ease of integration in industrial process flows. However, the relation between the surface chemistry, the passivating agent, and the growth-blocking efficacy of such treatments is not well understood which can lead to suboptimal passivation performance. This work investigates the reaction between dimethylamino-trimethylsilane (DMA-TMS) and SiO2 surfaces with varying composition, and identifies the impact of surface composition on passivation efficacy and selectivity. DMA-TMS reacts rapidly with Si–OH groups on SiO2 in a self-limiting surface reaction, resulting in an –O–Si(CH3)3 covered surface. In contrast, Si–O–Si groups are either unreactive or significantly less reactive towards DMA-TMS. Increasing the number of Si–OH versus Si–O–Si groups on the initial SiO2 surface therefore results in a higher –O–Si(CH3)3 density after DMA-TMS treatment. As a consequence, the selectivity of an ASD process towards SiO2 improves, as demonstrated for ruthenium atomic layer deposition from 1-ethylbenzyl-1,4-cyclohexadienyl-ruthenium and oxygen. This work illustrates the impact of tuning surface composition on passivation and selectivity for ASD.

Nanosheet Field-Effect Transistors (FETs) are candidates to replace today’s finFETs as they offer both an enhanced electrostatic control and a reduced footprint. The processing of these devices involves the selective lateral etching, also called cavity etch, of the SiGe layers of a vertical Si/SiGe superlattice, to isolate the future vertically stacked Si channels. In this work, we evaluate the capabilities of various conventional Critical Dimension (CD) and alternative spectroscopic techniques for this challenging measurement of a buried CD. We conclude that Raman and energy-dispersive X-ray spectroscopies are very promising techniques for fast inline cavity depth measurements.

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.

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. Beyond the problem of spatial resolution in a 3D SIMS experiment, one is also faced with the impact of changes in topography during the analysis. These are quite difficult to identify because they originate from the different sputter rates of the various materials and or phases in a heterogeneous system and are notorious at the interfaces between organic and inorganic layers. As each of these materials will erode at a different velocity, accurate 3D-analysis will require means to establish a spatially resolved relation between ion bombardment time and depth. Inevitably such a nonhomogeneous erosion will lead to the development of surface topography. The impact of these effects can be overcome provided one can capture the time and spatially dependent surface erosion (velocity) with high spatial resolution during the course of a profiling experiment. Incorporating a Scanning Probe Microscope (SPM) unit which provides topography measurements with high spatial resolution, into a SIMS tool (e.g., Time of Flight (ToF) SIMS) with means to alternate between SPM and SIMS measurements, is one approach to meet that demand for complementary topographical information allowing accurate 3D chemical imaging. In this paper, the result of integrating a SPM module into a ToF-SIMS system is presented illustrating the improvements in 3D data accuracy which can be obtained when analyzing complex 3D-systems. ispartof: ANALYTICAL CHEMISTRY vol:92 issue:16 pages:11413-11419 ispartof: location:United States status: published

Photoemission has always played an important role in the development of new microelectronic devices and processes and has quickly focused on the use of monochromatized Al Kd radiation in most commercial instruments. While, for instance, ARXPS using sample tilting or the use of high-energy photoemission at synchrotron facilities were available, their use remained confidential due to technical constraints such as measurement time, repeatability of the measurements and/or access to the facilities. In this paper, we show through some examples that the implementation of these features in a user-friendly setup in the laboratory considerably enhances the information retrieved from photoemission experiments.

We demonstrate multiple ways to reduce the D IT of Si-cap-free low-Ge-content (25-30%) SiGe gate stack. The D IT is reduced by i) Ge oxide scavenging via Ge condensation or by the work function metal (WFM), ii) nitridation of gate dielectrics and iii) optimized high-pressure anneal (HPA). A moderate nitridation of the interface layer (IL) is beneficial in EOT and D IT reduction, while nitridation of the HfO 2 dramatically reduces D IT by negating an ALD TiN-induced D IT increase. The optimized gate stack is evaluated in 8-nm-wide strained Si 0 7 Ge 0 3 pFinFETs integrated on 300 mm Si wafers, for which a 35% improvement in high-field mobility is demonstrated as compared to Si pFinFET counterparts.

This paper discusses the implementation of GHz-Scanning Acoustic Microscopy (GHz-SAM) into a wafer level scanning tool and its application for the detection of delamination at the interface of hybrid bonded wafers. It is demonstrated that the in-plane resolution of the GHz-SAM technique can be enhanced by thinning the sample. In the current study this thinning step has been performed by the ion beam of a ToF-SIMS tool containing an in-situ AFM, which allows not only chemical analysis of the interface but also a well-controlled local thinning (size, depth and roughness).

In this study of nanoscale etching for state-of-the-art device technology the importance of the nature of the surface oxide, is demonstrated for two III-V materials. Etching kinetics for GaAs and InP in acidic solutions of hydrogen peroxide are strikingly different. GaAs etches much faster, while the dependence of the etch rate on the H+ concentration differs markedly for the two semiconductors. Surface analysis techniques provided information on the surface composition after etching: strongly non-stoichiometric porous (hydr)oxides on GaAs and a thin stoichiometric oxide that forms a blocking layer on InP. Reaction schemes are provided that allow one to understand the results, in particular the important difference in etch rate and the contrasting role of chloride in the dissolution of the two semiconductors.

© 2018 Elsevier B.V. Retrieving molecular information by sputtering of organic systems has been concretized in the last years due to the introduction of sputtering by large gas clusters which drastically eliminated the compound degradation during the analysis and has led to strong improvements in depth resolution. Rapidly however, a limitation was observed for heterogeneous systems where inorganic layers or structures needed to be profiled concurrently. As opposed to organic material, erosion of the inorganic layer appears very difficult and prone to many artefacts. To shed some light on these problems we investigated a simple system consisting of aluminum delta layer(s) buried in a silicon matrix in order to define the most favorable beam conditions for practical analysis. We show that counterintuitive to the small energy/atom used and unlike monoatomic ion sputtering, the information depth obtained with large cluster ions is typically very large (∼10 nm) and that this can be caused both by a large roughness development at early stages of the sputtering process and by a large mixing zone. As a consequence, a large deformation of the Al intensity profile is observed. Using sample rotation during profiling significantly improves the depth resolution while sample temperature has no significant effect. The determining parameter for high depth resolution still remains the total energy of the cluster instead of the energy per atom in the cluster. ispartof: Applied Surface Science vol:444 pages:633-641 status: published

Gallium nitride (GaN) grown on Si by metalorganic chemical vapor deposition was analyzed using high-resolution, high-energy x-ray photoelectron spectroscopy (HAXPES). The HAXPES spectra of GaN obtained using monochromatic Cr Kα radiation at 5414.7 eV include a survey scan (Al Kα) and high-resolution spectra of Ga 3d, Ga 2p3/2, Ga 3p, Ga LMM, N 1s, C 1s, and O 1s.

High mobility channel materials like SiGe, Ge and IIIV receive lots of interest in order to enable the continuation of Moore’s path during the upcoming technology nodes. Recently Si-cap-free SiGe passivation with the number of interface states (NIT) down to 2 1011 cm-2 have been demonstrated. [1-3] A clear correlation was established between Ge-content in the SiGe-oxide and NIT. Unfortunately no process information has been provided on how the Ge-oxide-free interlayers were obtained. In a separate study the impact of HF, HCl and SC1 cleaning solution on the SiGe surface and oxide composition was reported. [4] A comparison of SiGe Gate-All-Around (GAA) and FinFET devices using a Si-cap-free SiGe 25% passivation scheme in a replacement metal gate (RMG) integration indicate the device performance is improved by a TMAH (aq) treatment prior to SiGe interlayer formation and high-k deposition. [5] Here the formation of a SiGe wet chemical oxide will be presented. The impact of dummy gate processing on the interlayer composition is reported. Also the impact of a TMAH (aq) treatment prior to chemical oxide formation has been analyzed and will be reported. Blanket strained SiGe 25% and 45% were grown by epitaxy. The SiGe-substrate and -oxide composition were measured by angle-resolved XPS using the Si2p and Ge3d peaks. The Ge3d peak is fitted with three different compounds: elemental Ge, GeO2 and Ge-suboxide. The angle dependence lets us estimate the distribution of the different components with respect to the sample top surface. An concentration increase with increasing angle (relative to the surface normal) indicates the compound is located closer to the sample surface. And reversely a concentration increase with increasing angle indicates the compound is located deeper into the sample. A native oxide was grown on SiGe 25 and 45% by exposing the wafers to the cleanroom air for approx. 1 week. The native oxide was found to be stoichiometric or nearly stoichiometric with a uniform Ge content throughout the oxide for SiGe 25 and 45% respectively. A wet chemical oxide was grown using an ‘imec clean’ [6] having a final O3/HCl (aq) rinse. The wet chemical oxide is Ge-poor compared to the SiGe substrate. No or only a small variation in Ge content of the SiGe-oxide is seen with ARXPS. However the fraction Ge-suboxide decreases with increasing angle, indicating the Ge-suboxide are located deeper within the sample, so closer to the SiGe-oxide/SiGe-substrate interface. The Ge-content of the SiGe-substrate after wet chemical oxidation shows a weak incident-angle-dependence, indicative a limited Ge enrichment of the SiGe substrate towards the SiGe-oxide/-substrate interface. The low Ge content of the SiGe-oxide is attributed to the water solubility of GeO2. The increase in Ge-content towards the SiGe-oxide/-substrate can be (at least partially) attributed to the poor water solubility of Ge-suboxide. The small increase in Ge content of the SiGe substrate can be attributed to the thermodynamically preferred oxidation of Si over Ge. The combined impact of dummy gate deposition, spike anneal and dummy gate removal prior to SiGe interlayer formation was investigated by AR-XPS and SIMS. The temperature used during spike anneal was found to have a significant impact on the Ge-content of the SiGe-oxide formed during an O3-last imec clean. The results will be reported in detail at the conference. The impact of TMAH (aq) on the chemical oxide composition and surface roughness will also be reported. TMAH (aq) was found to improve SiGe device performance. [5] Also the interaction with the subsequent HfO2 deposition will be reported. In summary SiGe is found to behave as a non-linear combination of Si and Ge. In HF-free aqueous solutions, the SiGe oxide composition is a combination of (1) thermodynamically preferred oxidation of Si versus Ge; (2) poor water-solubility of SiO2 and/or its low solubilization rate; and (3) fast dissolution of GeO2 but slow dissolution of Ge-suboxides. [1] CH Lee et al. VLSI 2016. [2] S. Siddiqui et al. presented MRS Spring Meeting 2016. [3] CH Lee et al. IEDM 2016. [4] S.L. Heslop et al. ECS Trans 69 (2015) 287. [5] H. Mertens et al VLSI 2015. [6] M. Meuris et al. Solid State Phenom, July 1995, p. 109. Figure 1

Several applications of two-dimensional (2D) semiconducting transition metal dichalcogenides (TMDs) in nanoelectronic devices require the deposition of ultrathin pinhole free high-κ dielectric films on 2D TMDs. However, deposition of nm-thin high-κ dielectric films on 2D TMDs remains challenging due to the inert TMD surface. Here, we demonstrate that the surface of a synthetic polycrystalline 2D MoS2 film is functionalized with SiO2 to enable the atomic layer deposition (ALD) of thin and continuous Al2O3 and HfO2 layers. The origins of nucleation, the growth mode, and layer coalescence process have been investigated by complementary physical characterization techniques, which can determine the chemical bonds, absolute amount, and surface coverage of the deposited material. SiO2 is prepared by oxidizing physical vapor deposited Si in air. The surface hydrophilicity of MoS2 significantly increases after SiO2 functionalization owing to the presence of surface hydroxyl groups. SiO2 layers with a Si content of...

For porous low-k film to be integrated into the next generation of interconnects, the pores need to be sealed against metal ions and barrier precursors. Self-assembled monolayers (SAMs) from organosilane precursor are spin coated onto 300mmk=2.2 low-k wafers. Two solvents, propylene glycol monomethyl ether acetate (PGMEA) and methanol with different dielectric constant of 8.3 and 20.1, are evaluated in terms of SAMs layer quality and sealing efficiency at coupon level. SAMs deposited from PGMEA show better sealing than SAMs deposited from methanol and therefore are selected for upscaling. Full wafer spin coating results show that a concentration of 0.05mM or below results in a partial coverage and a tilt angle as high as 70° from the backbone to the normal. Aggregation is observed for all tested concentrations and is worse for higher concentrations, which is possibly induced by the non-negligible presence of water in PGMEA solvents. In order to test the sealing efficiency of the SAMs layer against metal barrier precursors, MnN films by chemical vapor deposition (CVD) and TaNx/Ta (TNT) films by physical vapor deposition (PVD) are deposited on SAM coated low-k wafers. HfO2 is also deposited by Atomic layer deposition (ALD), which is not considered as a barrier but to test the sealing against ALD precursors. Depth profiling Rutherford Backscattering Spectrometry (RBS) measurements indicate an effective sealing of SAMs against CVD and ALD precursors but not against PVD barrier. Display Omitted SAMs are spin coated onto 300mm low-k wafers. After SAMs deposition, źk is 0.1 and decreases to 0.03 after annealing.Solvent dielectric constant affect the pre-condensation of SAMs and therefore sealing.RBS measurements shows that SAMs seal against MnN by CVD but not TNT by PVD.

Layers composed of binary blends of a polymer and a fullerene derivative are at the heart of bulk heterojunction organic photovoltaic cells. The efficiency and stability of these devices critically depend on the distribution of the polymer and fullerene materials within the blend layer. Whereas time-of-flight secondary ion mass spectrometry, particularly in combination with cluster ion beams, has frequently been used to probe similar organic materials, the quantification of the results is often missing due to a lack of understanding of all the parameters influencing the measurement results. This study contributes to improved quantification by exploring the role of the bulk composition and interfacial material on parameters such as sputtering yield, mass fragmentation, and ionization. We show that the argon cluster sputtering yields of these materials may be described by two widely acknowledged sputtering yield relationships. Their fitting parameters depend on the layer composition in a manner that is consistent with a lower energy required for sputtering of layers with higher fullerene derivative content. Similarly, we show that changes in composition impact the ion yields nonlinearly, which is an important source of quantification uncertainty. We provide evidence that, for the case of the fullerene derivative mixed with different donor materials, the matrix effect (i.e., the deviation from a linear response) correlates linearly with the electronegativity of the species in the donor material. Finally, with respect to the quantification of the composition at the interface with the substrate, we present a charge transfer mechanism that describes observed enhancements of the secondary ion intensities. ispartof: Journal of Physical Chemistry C vol:120 issue:49 pages:28074-28082 status: published

For the integration of two-dimensional (2D) transition metal dichalcogenides (TMDC) with high-performance electronic systems, one of the greatest challenges is the realization of doping and comprehension of its mechanisms. Low-temperature atomic layer deposition of aluminum oxide is found to n-dope MoS

The increasing scientific and industry interest in 2D MX

We have demonstrated Ge nFinFETs with a record high $\text{G}_{\text{mSA}\Gamma}/\text{SS}_{\text{SAT}}$ and PBTI reliability by improving the RMG high-k last process. The SiO 2 dummy gate oxide (DGO) deposition and removal processes have been identified as knobs to improve electron mobility and PBTI reliability even with a nominally identical Si-passivated Ge gate stack. Surface oxidation of Ge channel during the DGO deposition is considered to impact the final gate stack. By suppressing the Ge channel surface oxidation, increasing mobility with decreasing fin width is obtained, whereas PBTI reliability, $\text{D}_{\text{IT}}$ of scaled fin as well as high-field mobility are improved by extending the DGO in-situ clean process, resulting in the record $\text{Gm}_{\text{SAT}}/\text{SS}_{\text{SAT}}$ of 5.4 at 73 nm Lg.

In this paper, we investigate the tuning of a SiON tunnel oxide layer composition, in order to meet the memory operation performance requirements of a 3D NAND charge trap cell. The characteristics are compared to a VariOT ONO engineered barrier or pure SiO2. The results show that the N content increase in the SiON leads to important erase improvement at the expense of retention, therefore causing a trade-off between these two parameters. A low N content however can bring the required improvement in erase for large memory window, without compromising retention.

Potential solutions for the reliability challenges of high- k metal gate (HKMG) integration into DRAM high-voltage peripheral logic devices are reported. A detailed study of Negative Bias Temperature Instability (NBTI)-degradation, supported by physical analysis, assessing the impact of various tuning components within the stack (interface layer, high-k fluorination and/or cap, metal gate) is presented. The presence of Nitrogen throughout the HKMG stack can originate either from high-k processing or metal-nitride gate electrode. It is shown that preventing nitrogen diffusion towards the Si/SiO 2 interface region, together with AIO x (and F) incorporation at the HKMG interface, can tune device threshold voltage and modulate access to donor trap-defect bands. The result of these effects is a vast improvement in NBTI performance.

The superior properties of diamond being the hardest, best thermally conductive, high chemical inert and low friction material makes it very attractive for use as a tip material in scanning probe microscopy (SPM). The commercial availability of micromachined Si probes at the beginning of the 1990s triggered soon the interest and need for different tip coatings such as diamond which was first wanted for increasing the tip lifetime. Although first reports on diamond growth from the wafer phase were first reported in the 1980s, it took until the early 1990s before first applications using diamond grown by chemical vapor deposition (CVD) appeared on the market. Therefore, the development of fabrication processes for diamond tips, especially for electrically conductive ones, required also substantial efforts on the development of the diamond coating knowhow itself. As commercial probe companies considered diamond probes as specialty probes with a small market size in the early days, it explains well why most diamond tip innovations were established by universities and research centers.

The epitaxial growth of Si layers on Si substrates in the presence of O atoms is generally considered a challenge, as O atoms degrade the epitaxial quality by generating defects. Here, we investigate the growth mechanisms for Si epitaxy on O atomic layers (ALs) with different O-contents and structures. O ALs are deposited by ozone (O3) or oxygen (O2) exposure on H-terminated Si at 50 °C and 300 °C respectively. Epitaxial Si is deposited by chemical vapor deposition using silane (SiH4) at 500 °C. After O3 exposure, the O atoms are uniformly distributed in Si-Si dimer/back bonds. This O layer still allows epitaxial seeding of Si. The epitaxial quality is enhanced by lowering the surface distortions due to O atoms and by decreasing the arrival rate of SiH4 reactants, allowing more time for surface diffusion. After O2 exposure, the O atoms are present in the form of SiOx clusters. Regions of hydrogen-terminated Si remain present between the SiOx clusters. The epitaxial seeding of Si in these structures is realized on H-Si regions, and an epitaxial layer grows by a lateral overgrowth mechanism. A breakdown in the epitaxial ordering occurs at a critical Si thickness, presumably by accumulation of surface roughness.

For patterned TiN/silicon oxide/low-k dielectric stack, fluorinated etch residues were detected on the TiN surface, the dielectric sidewall and bottom, regardless of the low-k material used in the stack. XPS results showed that they consisted of polymer-based (CFx) residues deposited on trench sidewall and bottom, and metal-based (TiFx) residues mainly deposited on top surface. In terms of post-etch residue removal, the efficiency of various wet clean solutions can be clearly distinguished for CFx, and TiFx using the same patterned porous low-k stack. These results also demonstrate that the removal of both TiFx and CFx residues generated during the plasma is possible in one step with optimized chemical and process.

The use of sacrificial self-assembled monolayers (SAMs) to prepare clean n-type GaAs (100) surfaces without band bending in vacuo is demonstrated. GaAs surface passivation using octadecanethiol SAMs after HCl cleaning is shown to lead to an enhancement of the room-temperature photoluminescence intensity. Synchrotron-radiation photoelectron spectroscopy (SRPES) finds that the interfacial oxide between GaAs and the SAM remains below the detection limit. Evidence for both Ga–S and As–S bonds at the GaAs–thiolate interface is found. The limited thermal stability of the SAM allows the desorption of the alkyl chains by in situ thermal annealing at temperatures above 180 °C, leaving S bonded to Ga behind. The resulting surface contains only a very small amount of O (0.05 ML coverage) and C (about 3% of the SAM remaining) and shows no band bending with the surface Fermi level close to the conduction band. Atomic layer deposition of Al2O3 on this surface occurs via the formation of Al–S bonds without introducing a...

The continued downscaling of micro and nanoelectronics devices has increased the importance of novel materials and their interfaces very strongly thereby necessitating the availability of adequate metrology and very tight process control as well. For instance, the introduction of materials like SiGe or III-V compounds leads to the need for the determination of the exact composition and thickness of the resulting thin films. Concurrent with this trend, one is faced with layer growth concepts such as aspect ratio trapping, which exploit the reduced dimensionality of the devices. As this leads to films with very different characteristics as compared to their blanket counterparts, characterization now has to be performed on thin films grown in very confined volumes (with dimensions ranging down to less than 10–20 nm) and standard analysis methods like X-Ray Photoelectron Spectroscopy, Secondary Ion Mass Spectrometry (SIMS) and Rutherford Backscattering Spectrometry, no longer seem applicable due to a lack of spatial resolution. On the other hand, techniques with appropriate spatial resolution like Atom Probe Tomography or Transmission Electron Microscopy are time consuming and suffer from a lack of sensitivity due to their highly localized analysis volume. In this paper, a novel concept termed Self Focusing SIMS, is presented which overcomes the spatial resolution limitations of SIMS without sacrificing the sensitivity. The concept is based on determining the composition of a specific compound using cluster ions which contain the constituents of the compound. Their formation mechanism implies that all cluster constituents originate from the same collision cascade and are emitted in close proximity (

The results described in this paper first demonstrate key differences between a plasma-exposed blanket porous dielectric sample and a patterned structure in terms of surface sealing induced by the patterning plasma using ellipsometric porosimetry characterization. While the blanket CVD organosilicate glass (nominal k-value = 2.4, ∼20% of porosity) surface was sealed by the C4F8/CF4-based plasma, the surface of the analogous patterned structure of 45 nm 1/2 pitch was found to be completely open after the same patterning plasma process. Second, the surface composition of the patterned feature, type of the residues generated during the plasma etch, and the effect of a subsequent wet clean step are presented. The experimental results demonstrate that the use of a relevant patterned test structure and its characterization represent an appropriate approach for the optimization of the etch and cleaning processes. The removal efficiency of various wet clean solutions, including dilute HF, citric acid, tetramethylammonium hydroxide:H2O2:H2O mixture, and a slightly alkaline formulated mixture, with regard to polymer residues, CFx, and metal-containing residues, TiFx, can be clearly distinguished using the patterned porous low-k stack. © The Author(s) 2016. Published by ECS. This is an open access article distributed under the terms of the Creative Commons

Solution processed polymer (donor) and fullerene (acceptor) bulk heterojunctions are widely used as the photo active layer in organic solar cells. Intimate mixing of these two materials is essential for efficient charge separation and transport. Identifying relative positions of acceptor and donor rich regions in the bulk heterojunction with nanometer scale precision is crucial in understanding intricate details of operation. In this work, a combination of Ar(+)2000 gas cluster ion beam and scanning probe microscopy is used to examine the lateral and vertical phase separation within regio-regular poly(3-hexylthiophene)(P3HT):phenyl-C60-butyric acid methyl ester (PCBM) bulk heterojunction. While the Ar(+)2000 gas cluster ion beam is used as a sputter tool to expose the underneath layers, scanning probe microscopy techniques are used to obtain two-dimensional (2D) electrical maps (with sub-2 nm lateral resolution). The electrical mapping is decoded to chemical composition, essentially producing lateral and vertical maps of phase separation. Thermal stress causes large PCBM-rich hillocks to form, and consequently affecting the balance of P3HT:PCBM heterojunctions, hence a negative impact on the efficiency of the solar cell. We further developed a method to analyze the efficiency of exciton dissociation based on the current maps and a loss of 20% in efficiency is observed for thermally degraded samples compared to fresh un-annealed samples.

X-ray Photoelectron Spectroscopy (XPS) is a widely used surface analysis technique with many well established industrial and research applications. The surface sensitivity (top 5-10 nm) of XPS and its ability to provide short-range chemical bonding information make the technique extremely popular in materials characterization and failure analysis laboratories. While its surface sensitivity is an important attribute, in some cases, the depth of analysis of XPS is not sufficient to analyze buried interfaces without first sputter etching the sample surface. However, sputter etching can often lead to alterations of the true surface chemistry. An alternative to sputter etching the sample is Hard X-ray Photoelectron Spectroscopy (HAXPES), available at some synchrotron facilities. HAXPES utilizes X-rays typically defined as having energies greater than 5 keV. By increasing the photon energy of the X-ray source, the mean free path of photoelectrons is increased, resulting in an increased information depth obtained from the sample. Depending on the energy used, these hard X-rays can provide depths of analysis three or more times than that of soft x-rays used on conventional XPS systems. HAXPES measurements are, therefore, more sensitive to the bulk, and contributions from the surface are minimized.1,2 This presentation will describe a laboratory-based instrument, the PHI Quantes, equipped with two scanning microprobe monochromated X-ray sources, Al Kα (1486.6 eV) and Cr Kα (5414.9 eV), thus enabling both traditional XPS and HAXPES experiments in the same instrument. Combining both soft and hard X-ray analyses, we can gain an even better understanding of composition with depth and information at buried interfaces. References Kobayashi, K. Hard X-ray photoemission spectroscopy, Nucl. Instr. Meth. Phys. Res. A 2009, 601, 32-47. Fadley, C.S. Hard X-ray Photoemission: An Overview and Future Perspective. In Hard X-ray Photoelectron Spectroscopy (HAXPS); Woicik, J. C., Ed; Springer: Switzerland 2016.