Structural and optical properties of various liquid samples are of particular importance for both chemical and biological applications. These characteristics can be readily obtained from highly accurate, non-destructive ellipsometric measurements in a wide wavelength range. However, for a reliable result, certain technical obstacles must be eliminated for this type of measurement, e.g., excluding the environmental vibrations and providing an aligned liquid surface are both essential. Previously, it was shown that by using an ellipsometric configuration with active pneumatic isolators, it is possible to obtain vital structural information from both liquid-air and liquid-liquid interfaces, revealing nanoscale surface structures. In this work, the method is further extended by incorporating infrared ellipsometry, expanding the accessible spectral range into the mid-infrared region for enhanced surface and compositional analysis.

In photovoltaic manufacturing, in-line characterization must accommodate both flat surfaces (e.g., TOPCon backside structures) and textured morphologies (e.g., alkaline-etched front surfaces). Conventional ellipsometry approaches typically address these conflicting geometries either by mechanical reconfiguration or by deploying multiple dedicated measurement heads/stations, which increases system footprint at the line level and overall cost. We present a device and method for specular reflection measurements on samples requiring different incidence planes, enabling retooling-free spectroscopic ellipsometry for in-line PV manufacturing.The core innovation is a geometric arrangement in which two non-parallel incidence planes intersect along a single common line. By placing the detection arm on this shared axis and using separate illumination arms, two incidence-plane modes can be realized with a compact three-arm configuration (two illumination arms and one shared detection arm), instead of four arms in a conventional implementation with two independent incidence planes. While the acquisition (integration) time is comparable to that of dedicated metrology heads, the proposed concept eliminates morphology-dependent mechanical changeover, i.e., retooling-related downtime is reduced to 0. The instrument was validated on a native-oxide reference, TOPCon stack measurements, and SiN layers on textured silicon. Owing to the robust mechanical design and mechanically registered geometry, maintenance and calibration are not expected to be more frequent than for conventional ellipsometer-head designs.

A major challenge in modern semiconductor, photonic, and quantum technology is the accurate characterization of ultrathin (<100 nm) patterns with ever-decreasing lateral feature sizes (<25 nm). In this study, we showcase ellipsometric porosimetry (EP) as an alternative, scalable metrology for model channel hole patterns. The critical dimensions of such features are typically below 100 nm, and thus their diameters can be determined via in situ optical observation of capillary evaporation-driven refractive index changes based on classical thermodynamic principles. We demonstrate that the EP-derived diameters of the model structures correlate well with both the expected values and those obtained from optical critical dimension (OCD) metrology. Since the accuracy of OCD decreases when probing deep into the subwavelength regime (<190 nm), EP emerges as a complementary metrology candidate, as its highest accuracy is typically for feature sizes of 1-25 nm. The method presented here can also be extended to more complex anisotropic structures.

Two-layer model systems were designed by covering a 130 nm thick mesoporous silica coating (30% porosity, 1.8 nm average pore radius) with a 470 nm thick chitosan coating (degree of acetylation 18-19%) to study the accumulation and release of a cationic model molecule (rhodamine 6G dye). The coatings were impregnated in the aqueous solution of the dye (pH 6.0, 7.4 and 8.8, 12 °C, 22 °C and 32 °C) to study the effect of electrostatic interactions and morphology on the dye uptake. The accumulation of dye molecules was examined in terms of the pseudo-first-order and pseudo-second-order kinetic model, while the release (at pH 7.4, 25 °C) in terms of the Korsmeyer-Peppas and Higuchi model. The release exponents (0.43-0.71) of the Korsmeyer-Peppas model revealed the significance of an interaction of the impregnation solution with the silica pore wall during dye uptake. According to the Higuchi model, a straight line with a higher and a lower slope could be fitted to the experimental points in the first ("fast rate") and second ("slow rate") stages of the process. Interestingly, the slope values and their differences significantly depended on the conditions of dye uptake: impregnation at alkaline pH not only increased the uptake but also resulted in faster release.

During the experimental formation of sol-gel coatings, the colloid dispersions go through a drying process, and the structure of the coatings is formed as a result of complex chemical, colloidal, and capillary interactions. While computer simulations provide guidelines to tune and even design the nanomaterials synthesis, simulations of coating structure formation are hitherto unknown in the literature. Based on real experiments, we establish here a ReaxFF reactive force field-based molecular dynamics simulation protocol in order to investigate and determine the role of the experimental conditions on the pore structure formation in the coatings. Anatase TiO2 sol-gel coatings with a thickness of 50 nm, 7% open porosity, and a 2.4 nm pore radius were prepared on solid substrates using the dip-coating method. In the computational synthesis of porous TiO2 layers, the attractive capillary forces present during the drying step were accounted for by applying an external pressure, and their effect on the coatings' pore structure was investigated. It was found that the TiO2 layer structure corresponding to an external pressure of 10,000 atm in the simulations exhibited a porosity comparable to that determined by experimental methods. This demonstrates the impact of immersion capillary forces on sol-gel layer formation. The created computer model accurately describes the layer structure using real parameters, making it suitable for designing the coating structure through computer simulation.

Thin (ca. 340 nm) chitosan coatings were deposited onto glass substrates via dip-coating, then modified with the methanol solution of decanoic anhydride (0.17-56 mM). NMR, FTIR and XPS measurements confirmed that the acylation degree increased from 18 % to 45 %, and at the highest degree, the whole layer was acylated homogeneously by the reagent molecules. The coating thickness increased (up to 60 %), and the refractive index decreased (from 1.541 to 1.532) due to the acylation, that was determined by UV-visible spectroscopy. The AFM did not reveal morphological changes, but wetting tests showed that the acylation rendered the coating hydrophobic (water contact angle increased from ca. 75 degrees to 100 degrees). The contact angle, however, decreased to 85 degrees due to the development of a second molecular layer of the decanoic acid by-product at the highest (over 25 mM) reagent concentrations. XRD studies showed a self-assembling structuring of the alkyl-chains in the bulk phase, which occurred in the case of the highest degree of acylation. This also manifested itself in a significant decrease of the layer hygroscopicity: the swelling degree decreased from 40 % to 8 % in a saturated water atmosphere monitored by spectroscopic ellipsometry.

This study focuses on processed wafers undergoing the chemical mechanical planarization (CMP) process, with a particular emphasis on monitoring the dielectric stack thickness between Cu VIA structures, patterned in approximately a 45 mu m raster. Spectroscopic ellipsometry was applied to determine the one-dimensional stack multilayer thickness, while imaging spectroscopic reflectometry was used to reveal the lateral thickness profile.

Silicon epitaxy is an essential building block in the manufacturing of complementary metal-oxide semiconductor (CMOS) devices. Accurate determination of epitaxial layer thickness is indispensable for a uniform and reproducible process. In this paper, we compare thickness values of the transition zone (TZ) in silicon epitaxial wafers obtained by two of Semilab's production-compatible electrical and optical characterization techniques: Fourier-transform infrared (FTIR) reflectometry and spreading resistance profiling (SRP). We demonstrate a high correlation between TZ thicknesses obtained from the optical modeling of FTIR reflectance spectra and SRP profiles. The dependence of TZ thickness change on the high-temperature annealing steps is also examined. FTIR reflectometry thus offers a quick, contactless alternative for obtaining structural parameters of an epitaxial layer, and these values can be well matched to those given by SRP.

Silica-based mesoporous films have been widely applied in the fabrication of advanced functional materials, such as anti-reflective coatings, bio-, and chemical sensing devices, due to their unique properties, e.g., high surface area, controlled porosity, and the ease and tailorability of their synthesis. Precise knowledge of their pore architecture is crucial, highlighting the need for accurate characterization tools. In this sense, ellipsometric porosimetry represents a powerful and versatile characterization platform, providing access to reliable information about total porosity, pore size, pore size dispersity, mechanical properties (Young's modulus) and surface area of a great variety of mesoporous thin films. While the underlying framework of modeling capillary condensation via the Kelvin equation is well established, one descriptor, the internal wettability of mesoporous architectures remains a challenging variable for reliable material characterization. Wetting on the nanoscale cannot be observed via the traditional drop-shape method, while approximating internal wetting by the macroscopic property can be inaccurate as the two wetting behaviors do not necessarily correlate. Herein, we present a method based on vacuum ellipsometric porosimetry for the determination of the internal contact angle of functionalized mesoporous silica thin films. Tuning of the surface energy for a known mesoporous architecture by methyl-functionalization enabled us to relate differences in the pore filling for various adsorptives (water, methanol, toluene, cyclohexane) to their internal contact angles. Our study serves as a guide for generalized internal contact angle determination suitable for a wide range of organic adsorptives and mesoporous sorbent materials.

The metrology FOUP (M-FOUP) is a custom-modified wafer carrier equipped with multi-point spectroscopic reflectometer metrology. The self-powered metrology apparatus is positioned above a FOUP slot holding the wafer to be measured. The measured points on the wafer are fixed by placing fiber probes on a permanent mounting plate. The measured reflectometry spectrums are analyzed based on optical modeling software. The M-FOUP SYSTEM consists of a controller (M-CONTROLLER), which controls multiple M-FOUP measurement units.In our previous publications, we focused on the technical details of the M-FOUP unit, such as the overall design, internal temperature distribution, and charging/discharging routine, as well as on the metrology job architecture and implementation of this unique concept into an operating fab environment. In this work, we compare the performance of the M-FOUP SYSTEM with the Process of Record (POR) metrology for typical high-volume applications.

The metrology FOUP (M-FOUP) is a self-contained metrology tool in a wafer carrier. This metrology concept, which was designed and manufactured by SEMILAB, is actively being evaluated in GLOBALFOUNDRIES. The M-FOUP system consists of a controller (MCONTROLLER), which controls multiple M-FOUP measurement units. Each independently operated M-FOUP unit utilizes a multi-point spectroscopic reflectometry technique, which can be used for many thickness applications. The self-contained metrology device has advantages over traditional film thickness measurement tools including reduced cost, significantly smaller footprint, and increased availability. In a previous article we focused on the technical details of the M-FOUP unit such as the overall design, the temperature distribution, charging/discharging routine, typical spectra, and typical wafer map. The focus of this work is on integrating the M-FOUP system into a semiconductor fab environment. This requires a high-level orchestration of multiple fab systems including the automated material handling system (AMHS), real-time dispatching (RTD) system and the MFOUP system itself. The management of the metrology jobs and data collection using M-FOUP from a point of view of Manufacturing Execution System (MES) are discussed.

We prepared mesoporous silica layers by sol-gel dip-coating technique on various substrates (silicon, polycarbonate, microscope glass and quartz) with the aid of a pore-forming triblock copolymer (Pluronic PE10500). The freshly deposited layers were aged in an aqueous ammonia solution atmosphere. Two types of thermal curing were implemented depending on the substrates: a low-temperature heat treatment at 120 degrees C for 13 hours or a high-temperature heat treatment at 480 degrees C for 1 hour. We carried out the porogen extraction of the copolymer molecules from the low-temperature heat-treated samples in a water washing step. Optical spectroscopy measurements gave evidence of a significantly improved and long-lasting light transmission of coatings. The maximum light transmission was 98.3% on glass and 97.6% on polycarbonate after 4 years of storage. TEM investigations showed thin layers with distorted face centred cubic structure. Spectroscopic ellipsometry and ellipsometric porosimetry studies showed a "two-layer" structure. The applied synthesis technique promoted the formation of a double layer structure with relatively thick (10-25 nm) pore sizes. The pseudomorphic transformation rearranged the silica/copolymer structure in presence of ammonia. The transformation was incomplete and resulted in a low porosity (23-34%) upper-layer and a high porosity (40-76%) lower-layer.

Bifunctional hybrid silica sol-gel coatings were synthesized, which showed both increased light transmittance and water-repellence. The as-prepared coatings of variable thickness (100-175 nm) were found to have low refractive index (1.250-1.275), high porosity (36%-42%), and maximum light transmittance up to 99.8%. Water-repellence of the surface was due to high water contact angle (90 degrees) and low contact angle hysteresis (1-2 degrees). Ellipsometric porosimetry and transmission electron microscopy measurements confirmed the microporous structure of the coatings. A systematic investigation for studying the durability and the deterioration of optical and surface properties was studied during aqueous soaking tests at different pH. During these experiments atomic force microscopy showed that the morphology of the surface did not change. The changes in the wetting properties were also confirmed by surface free energy measurements and an increase of the polar component was observed. The optical properties could be regenerated completely or partially after the soaking via heat treatment at 400 degrees C. The light transmittance of the samples remained high after the soaking, most likely due to the swelling of the solid matrix. The light transmittance and the water-repellent properties of the coatings showed long-term stability up to a year of storage.

A novel optical reflectometry solution, capable of measuring planar, blanket thin films on 300mm Si wafers within a self-contained and portable Front Opening Unified Pod (FOUP)-based compact metrology system, the Metrology-FOUP (M-FOUP) System, is introduced. Key applications of the new instrument are presented by demonstrating measurement of unpatterned film thickness on samples representing typical daily qualification of process equipment. Benchmark data on characteristic samples from semiconductor production fab are presented, together with comparing the test results to that measured by conventional (stand-alone) metrology tools.

GaAs based vertical cavity surface emitting lasers (VCSELs) have one of the fastest growing markets due to their numerous applications in imaging technology, optical sensors, and interconnects. Stable, single-mode operation of these laser diodes is often achieved by forming subwavelength structures on the surface of the GaAs semiconductor. Quick and preferably noncontact inspection of the formed nanostructures is desired during the fabrication process. Nanostructure characterization by spectral ellipsometry-based metrologies has become an indispensable tool in the semiconductor industry. An advanced method of ellipsometry is the application of Mueller-matrix ellipsometry, which enables the characterization of structure details difficult to measure or not reachable by using standard ellipsometry measurements. In this paper, the authors present the results of nanostructure characterization by model-based dimension metrology using spectral ellipsometry and Mueller-matrix spectral ellipsometry of line gratings formed on GaAs substrates during the process of VCSEL fabrication.

In this work, we review some techniques used for the characterization of ion implanted layers, with the aim to identify the best approach in various experimental conditions.With regard to dopant profiles, Secondary Ion Mass Spectrometry (SIMS) or Time-of-Flight (ToF)-SIMS are discussed. In the case of very thin layers (of the order of 10 nm) and for specific elements, ToF-SIMS is the best choice. For some devices, it is also necessary to analyse rather thick layers with low dopant concentration, and in this case dynamic SIMS gives better performances.Mass spectroscopy cannot provide information about the electrical activity of dopants. The profile of electrically active dopants can be obtained by the Differential Sheet Resistance (DSR) and Hall Resistance (HR) technique. This technique has the advantage that the carrier density and mobility are independently measured, thus providing information about the crystal quality in the layer, in addition to the dopant distribution. In the Spreading Resistance (SR) technique, a resistance profile is measured and turned into a carrier concentration profile with the aid of literature mobility data or by comparison with data from reference samples with known doping concentration. This approach may lead to wrong concentration data if the carrier mobility is degraded, for instance because of unrecovered damage.Various microscopy techniques are commonly used for the analysis of residual crystal defects, for instance the Transmission Electron Microscopy (TEM) and the Scanning Electron Microscopy (SEM) associated with selective etching. Recently, a new technique based upon micro-photoluminescence (μ-PL) measurements (so-called “EnVision”) proved to be a valid alternative to selective etching. A study about the residual damage after silicon implantation and annealing is reported. The conclusions reached by selective etching and conventional microscopy and by micro-photoluminescence are consistent with each other, but micro-photoluminescence has the advantage of providing a non-destructive analysis of large silicon areas.The best approach for monitoring metal contamination depends on the specific contaminant and hence of the contamination mechanism. Minority carrier lifetime measurements are suitable for fast diffusing contaminants (e.g. iron), whereas DLTS provides better sensitivity for slow diffusers such as molybdenum and tungsten.

Silica sol-gel coatings on different substrate materials and their use as model systems have been studied. Mesoporous silica coatings with thicknesses of 85 - 135 nm and porosity of 18 ˗ 37% were prepared by dip-coating on polycarbonate and glass substrates. In order to eliminate the shrinkage of the porous structure acid or base vapour treatment was applied. Thickness and refractive index of the coatings were determined by analysing the transmittance spectra of the samples. Ellipsometric porosimetry measurements were carried out to determine the porosity, pore radius distribution, thickness and refractive index. The thickness of the samples was further confirmed by scanning electron microscopy. The adsorption capac ity of the porous coatings was also studied by dye impregnation tests. The temporal stability of the samples was investigated by UV-Vis spectrometry and it was found that the advantageous optical properties (T max = 98 – 99%) of the samples remained constant even after a 1 year storage period.

Amorphous and crystalline electrochromic WO3 films exhibit quite different optical properties during coloration process. In the present work, amorphous and crystalline electrochromic WO3 films prepared by a solution method were characterized using X-ray diffraction, scanning electron microscope, and transmission electron microscope techniques. A double-layer model with sharp interfaces was established for the fitting of the ellipsometry parameters. The results show that the proton favors amorphous films more than crystalline WO3 films. The refractive indices of both amorphous and polycrystalline WO3 films decrease while extinction coefficients increase with the inserting of H+ during the coloration process. But the optical parameters of the latter are much more sensitive to the H+ ions injected compared to the amorphous WO3 during the coloration process. That is the refractive index modulation of the crystalline WO3 films is about 53% at 633 nm while that of the amorphous films about 15% at the same wavelength. The Drude-like free electron model for crystalline WO3 and hopping mechanism of small polaron for amorphous WO3 are used to explain the difference in detail. These results are very helpful for the better understanding of the coloration process and for the design of electrochromic devices. (C) 2016 Elsevier B.V. All rights reserved.

Mesoporous silica films with vertically aligned hexagonal pores have been produced via the electrochemically assisted surfactant assembly (EASA) method using cetyltrimethylammonium bromide (CTAB) surfactant. Mesoporous silica powder has also been synthesised using the same surfactant. The pore walls of the silica powder and films have been grafted with organosilane reagents. The size of the pore, degree of grafting and effect on the properties of the pore have been investigated using porosimetry, contact angle, NMR and CHN analysis. The degree of grafting was found to be dependent upon the size of the grafting agent, with the smallest steric bulk grafting most effectively. It was found that the grafting of the pores with Me3SiCl greatly increased the hydrophobicity of the pore and reduced water penetration. Grafting with larger groups caused the film surface to be hydrophobic but had little effect on the penetration of water into the pores.