Advanced Metrology Research Articles

Integration of Metrology in Grinding and Polishing Processes for Rotationally Symmetrical Aspherical Surfaces with Optimized Material Removal Functions

Aspherical surfaces, with their varying curvature, minimize aberrations and enhance clarity, making them essential in optics, aerospace, medical devices, and telecommunications. However, manufacturing these surfaces is challenging because of systematic errors in CNC equipment, tool wear, measurement inaccuracies, and environmental disturbances. These issues necessitate precise error compensation to achieve the desired surface shape. Traditional methods for spherical optics are inadequate for aspherical components, making accurate surface shape error detection and compensation crucial. This study integrates advanced metrology with optimized material removal functions in the grinding and polishing processes. By combining numerical control technology, computer technology, and data analysis, we developed CAM software (version 1) tailored for aspherical surfaces. This software uses a compensation correction algorithm to process error data and generate NC programs for machining. Our approach automates and digitizes the grinding and polishing process, improving efficiency and surface accuracy. This advancement enables high-precision mass production of rotationally symmetrical aspherical optical components, addressing existing manufacturing challenges and enhancing optical system performance.

Uncertainty Calculation as a Service: Integrating Cloud-Based Microservices for Enhanced Calibration and DCC Generation.

The calibration industry is renowned for its diverse and sophisticated equipment and complex processes, which necessitate innovative solutions to keep pace with rapidly advancing technology. This paper introduces an enhancement to an existing microservice-based cloud architecture, aimed at effectively managing the inherent complexity within this field. The enhanced architecture seamlessly integrates various equipment types and communication technologies, aligning diverse stakeholder expectations into a unified system that ensures efficient and accurate calibration processes. It highlights the integration of microservices to facilitate various methods of uncertainty calculation and the generation of digital calibration certificates (DCCs). A case study on RF power measurement illustrates the practical application and benefits of the enhanced architecture. Although initially focused on RF power measurement, the flexible architecture allows for future expansions to accommodate new standards and measurement techniques. The enhanced system offers a comprehensive approach to managing data flow from calibration equipment to the final generation of DCCs, utilizing cloud-based services for efficient data processing. As a future direction, this extension sets the groundwork for broader applicability across multiple measurement types, ensuring readiness for upcoming advancements in metrology.

Atomic Precision Processing of Two-Dimensional Materials for Next-Generation Microelectronics.

The growth of the information era economy is driving the pursuit of advanced materials for microelectronics, spurred by exploration into "Beyond CMOS" and "More than Moore" paradigms. Atomically thin 2D materials, such as transition metal dichalcogenides (TMDCs), show great potential for next-generation microelectronics due to their properties and defect engineering capabilities. This perspective delves into atomic precision processing (APP) techniques like atomic layer deposition (ALD), epitaxy, atomic layer etching (ALE), and atomic precision advanced manufacturing (APAM) for the fabrication and modification of 2D materials, essential for future semiconductor devices. Additive APP methods like ALD and epitaxy provide precise control over composition, crystallinity, and thickness at the atomic scale, facilitating high-performance device integration. Subtractive APP techniques, such as ALE, focus on atomic-scale etching control for 2D material functionality and manufacturing. In APAM, modification techniques aim at atomic-scale defect control, offering tailored device functions and improved performance. Achieving optimal performance and energy efficiency in 2D material-based microelectronics requires a comprehensive approach encompassing fundamental understanding, process modeling, and high-throughput metrology. The outlook for APP in 2D materials is promising, with ongoing developments poised to impact manufacturing and fundamental materials science. Integration with advanced metrology and codesign frameworks will accelerate the realization of next-generation microelectronics enabled by 2D materials.

Robust inverse parameter fitting of thermal properties from the laser-based Ångstrom method in the presence of measurement noise using physics-informed neural networks (PINNs)

The two-dimensional laser-based Ångstrom method measures the in-plane thermal properties for anisotropic film-like materials. It involves periodic laser heating at the center of a suspended film sample and records its transient thermal response by infrared imaging. These spatiotemporal temperature data must be analyzed to extract the unknown thermal conductivity values in the orthotropic directions, an inverse parameter fitting problem. Previous demonstration of the metrology technique used a least-squares fitting method that relies on numerical differentiation to evaluate the second-order partial derivatives in the differential equation describing transient conduction in the physical system. This fitting approach is susceptible to measurement noise, introducing high uncertainty in the extracted properties when working with noisy data. For example, when noise of a signal-to-noise ratio of 10 is added to simulated amplitude and phase data, the error in the extracted thermal conductivity can exceed 80%. In this work, we introduce a new alternative inverse parameter fitting approach using physics-informed neural networks (PINNs) to increase the robustness of the measurement technique for noisy temperature data. We demonstrate the effectiveness of this approach even for scenarios with extreme levels of noise in the data. Specifically, the PINN-approach accurately extracts the properties to within 5% of the true values even for high noise levels (a signal-to-noise ratio of 1). This offers a promising avenue for improving the robustness and accuracy of advanced thermal metrology tools that rely on inverse parameter fitting of temperature data to extract thermal properties.

3D scanning techniques in power engineering

Information about component geometry is a key parameter for assessing residual life and monitoring degradation processes during the life cycle of a technology. High-precision optical measurement systems are complex metrology devices that enable the collection of complex data on the physical properties of components and their rapid evaluation in CAD-based programs. These solutions offer an analysis of changes in component characteristics over time and comparing them with as-built documentation. The quality of production can be evaluated by comparing the condition of the equipment with the product documentation or monitoring the influence of service conditions on the degradation of the equipment and the trend of future development of defects. All this in digital form of data, which enables new progressive approaches to repair and maintenance programs of monitored equipment. The use of advanced metrology and diagnostic systems and the procedures they offer can reduce the time required for measurement by conventional methods and multiply the data yield from metrology, which in conjunction with modern IT technologies can detect new degradation mechanisms and increase safety service and extend projected lifetime. Up-to-date technology data can significantly save on maintenance costs or even eliminate maintenance procedures. It also provides important data for the setup of LTO.

Mitigating the Impact of Asymmetric Deformation on Advanced Metrology for Photolithography

Controlling overlay in lithography is crucial for improving the yield of integrated circuit manufacturing. The process disturbances can cause undesirable morphology changes of overlay targets (such as asymmetric grating), which can significantly impact the accuracy of overlay metrology. It is essential to decouple the overlay target asymmetry from the wafer deformation, ensuring that the overlay metrology is free from the influence of process-induced asymmetry (e.g., grating asymmetry and grating imbalance). Herein, we use an asymmetric grating as a model and show that using high-diffraction-order light can mitigate the impact of asymmetric grating through the rigorous coupled-wave analysis (RCWA) method. In addition, we demonstrate the diffraction efficiency as a function of the diffraction order, wavelength, and pitch, which has guiding significance for improving the measurement accuracy of diffraction-based overlay (DBO) metrology.

Microtexturing of industrial surfaces via radial ultrasonic vibration-assisted machining: An analytical model and experimental validation

The aim of this paper is to develop an analytical model to predict different texture patterns obtained with Radial Ultrasonic Vibration Assisted Machining (RUVAM) and estimate the dimensions of their characteristic features. It is also validated experimentally by performing advanced surface metrology on C45 specimens. The model is based on considering the machining of craters along radial tracks as the main texturing mechanism due to the change in the effective depth of cut provoked by the ultrasonic vibration of the insert. Mathematical formulae composing the model are then developed by considering how the machined craters in those tracks interact radially and axially, describing the final texture as the result of a multidirectional geometrical interaction. To predict how those interactions take place depending on the manufacturing parameters chosen, threshold values for the feed rate and the depth of cut are proposed. They also allow the validation of the formulae that estimate the different geometrical descriptors of craters (radial and axial heights and widths). According to the different combinations of parameters, the model succeeds in proposing diverse potential texturing scenarios. In the second part of this paper, a full factorial design is planned and applied on C45 specimens to validate the results with a RUVAM tool of 40 kHz and a 1 μm-amplitude. The plan includes three factors (insert nose radius, depth of cut and feed rate). Their levels are defined according to the threshold values for feed and depth of cut defined by the model to reproduce different textures. Results prove that the proposed threshold values allow a very good assessment of the resulting microtexturing structures on the surfaces. The measured values of widths and heights are in agreement with the values predicted by the model. With this technique, the heights of the textured surfaces span from 5 to 400 μm and widths from 45 to 720 μm, depending on the selected parameters. In the radial direction, the vibratory motion of the insert is robustly imprinted on the material, with radial heights and widths of around 2 μm and 39.6 μm, agreeing with the model. In overall, errors comparing the experimental measurements and the values predicted by the model rise up to 9%, although this error can reach 15% at some cases on radial descriptors because of their higher sensitivity to the F-filtering. A last texturing mechanism can be attributed to RUVAM related to the shaping of craters, as different oval permeters can be obtained by combining the parameters adequately. All these results lead to potential future studies related with the functional implications of all the detected textures.

Predictive and prospective calibrated TCAD to improve device performances in sub-20 nm gate length p-FinFETs

In this paper we present an extended analysis of thsse impact of SiGe p-epi source/drain engineering on sub-20 nm gate length p-FinFETs performance for the N7 technology node. Different Ge concentrations and profiles (graded versus non-graded) are evaluated making use of properly calibrated drift-diffusion TCAD simulations. Calibration of simulations is based on advanced metrology and on Monte-Carlo simulations such that the resulting simulated ID-VG (in LIN and SAT regimes) matches the one measured on device. The calibrated TCAD simulator is then used to understand the limited performances of the device and to propose new source/drain epi architectures with graded and increased Ge content. A new p-FinFET design is fabricated and tested, confirming a boost in ON-current and a reduction of the parasitic resistance. Prospective TCAD work is also presented suggesting possible future improvements on p-epi source/drain and on local interconnect contacts.

INTELLIGENT MONITORING SYSTEM FOR REAL-TIME OPTIMIZATION OF ULTRA-PRECISION MANUFACTURING PROCESSES

In the realm of ultra-precision manufacturing, the minutiae of process control and material handling are paramount to achieving the highest levels of product quality and manufacturing efficiency. The industry faces a significant challenge: maintaining and enhancing the precision of manufacturing processes in real-time to ensure optimal output quality while minimizing waste and energy consumption. This challenge is compounded by the increasing complexity of products and the materials used, requiring ever more precise and adaptive manufacturing techniques. The importance of addressing this challenge cannot be overstated, as it directly impacts the competitiveness, sustainability, and innovation capacity of manufacturing firms. The development of an intelligent monitoring system that integrates advanced precision metrology techniques presents a promising solution to this problem. Such a system would enable real-time optimization of manufacturing processes, leveraging cutting-edge technologies and data analytics to dynamically adjust parameters for optimal performance. By doing so, it would not only enhance the precision and efficiency of manufacturing operations but also contribute significantly to sustainable manufacturing practices by reducing waste and energy consumption. This concept paper proposes the development of this intelligent monitoring system, outlining its potential impact on the ultra-precision manufacturing industry.
 Keywords: Ultra Precision, Monitoring, Processing, Real Time.

INFLUENCE ANALYSIS OF THREE DIFFERENT CAMERA CALIBRATION METHODS ON A CAMERA-PROJECTOR MEASURING SYSTEM

The challenges arising from mass production with high quality level require advanced error measurement systems and optical metrology systems. Nowadays, it is more frequent to find this type of controls at the manufacturing industry into the quality control procedures as long as the need for a faster capture speed and precision has increased. However, these techniques can be improved. The accuracy of 3D measurement systems formed by a camera-projector pair depends directly on the calibration procedure used. The projector is usually modelled as the inverse projection of a pin-hole camera, which presents the option to calibrate the system by two different approaches: as a whole system or separately. The most common approach is the use of a camera previously calibrated, followed by the calibration of the projector. Studies show that the uncertainty of the camera parameters from its calibration propagates to the projector parameters and several authors conclude that the three most widespread are: Tsai, Zhang and Direct Linear Calibration. The objective of this study is to have a clear comprehension of the relationships between the camera and projector parameters and of how uncertainty is propagated to the measurement system error. Therefore, the three calibration methods previously mentioned and some of them possible combinations are analyzed.

Future of precision manufacturing: Integrating advanced metrology and intelligent monitoring for process optimization

Precision manufacturing is undergoing a transformative evolution fueled by the integration of advanced metrology techniques and intelligent monitoring systems. This abstract explores the future trajectory of precision manufacturing through the convergence of these technologies, focusing on their synergistic role in process optimization. Advanced metrology techniques, including high-resolution imaging, laser scanning, and non-contact surface measurement, provide unprecedented levels of accuracy and detail in capturing dimensional data. These techniques enable manufacturers to precisely analyze component geometry, surface finish, and tolerances, facilitating the production of parts with exceptional precision and quality. Moreover, the integration of metrology within the manufacturing process allows for real-time feedback, enabling rapid adjustments and corrections to ensure adherence to design specifications. Intelligent monitoring systems complement advanced metrology by continuously collecting data from various sensors embedded within manufacturing equipment. These systems utilize artificial intelligence (AI) and machine learning algorithms to analyze vast amounts of data in real-time, detecting anomalies, predicting equipment failures, and optimizing process parameters. By leveraging data-driven insights, manufacturers can enhance production efficiency, minimize downtime, and reduce scrap rates. The synergy between advanced metrology and intelligent monitoring extends beyond quality control to encompass holistic process optimization. Through the seamless integration of these technologies, manufacturers can achieve unparalleled levels of precision, efficiency, and flexibility in their operations. For instance, real-time metrology feedback combined with AI-driven monitoring enables adaptive manufacturing processes that dynamically adjust parameters based on changing environmental conditions or material properties. Furthermore, the future of precision manufacturing lies in the adoption of a digital twin approach, where virtual replicas of physical manufacturing systems are created and synchronized with real-time data. This enables predictive maintenance, virtual prototyping, and simulation-based optimization, leading to significant cost savings and accelerated innovation cycles. The future of precision manufacturing hinges on the integration of advanced metrology and intelligent monitoring technologies. By harnessing the synergies between these innovations, manufacturers can achieve unprecedented levels of precision, efficiency, and agility, driving forward the evolution of manufacturing in the digital era.

Structured illumination ptychography and at-wavelength characterization with an EUV diffuser at 13.5 nm wavelength.

Structured illumination is essential for high-performance ptychography. Especially in the extreme ultraviolet (EUV) range, where reflective optics are prevalent, the generation of structured beams is challenging and, so far, mostly amplitude-only masks have been used. In this study, we generate a highly structured beam using a phase-shifting diffuser optimized for 13.5 nm wavelength and apply this beam to EUV ptychography. This tailored illumination significantly enhances the quality and resolution of the ptychography reconstructions. In particular, when utilizing the full dynamics range of the detector, the resolution has been improved from 125 nm, when using an unstructured beam, to 34 nm. Further, ptychography enables the quantitative measurement of both the amplitude and phase of the EUV diffuser at 13.5 nm wavelength. This capability allows us to evaluate the influence of imperfections and contaminations on its "at wavelength" performance, paving the way for advanced EUV metrology applications and highlighting its importance for future developments in nanolithography and related fields.

Battery Electrode Slurry Rheology and its Impact on Manufacturing

The manufacturing of battery electrodes is a critical research area driven by the increasing demand for electrification in transportation. This process involves complex stages during which advanced metrology can be...

Engineering electron-electron interaction for advanced quantum metrology in electron microscopy

Engineering electron-electron interaction for advanced quantum metrology in electron microscopy

Time interval measurement with linear optical sampling at the femtosecond level

High-precision time interval measurement is a fundamental technique in many advanced applications, including time and distance metrology, particle physics, and ultra-precision machining. However, many of these applications are confined by the imprecise time interval measurement of electrical signals, restricting the performance of the ultimate system to a few picoseconds, which limits ultrahigh precision applications. Here, we demonstrate an optical means for the time interval measurement of electrical signals that can successfully achieve femtosecond (fs) level precision. The setup is established using the optical frequency comb (OFC) based linear optical sampling (LOS) technique to realize timescale-stretched measurement. We achieve a measurement precision of 82 fs for a single LOS scan measurement and 3.05 fs for the 100-times average with post-processing, which is three orders of magnitude higher than the results of older electrical methods. The high-precision time interval measurement of electrical signals can substantially improve precision measurement technologies.

Deployable optics for the Buccaneer Main Mission (BMM)

AbstractDefence Science and Technology Group (DSTG) is currently preparing for the launch of the Buccaneer Main Mission (BMM) satellite, the successor to the Buccaneer Risk Mitigation Mission (BRMM). BMM hosts a high-frequency (HF) antenna and receiver to contribute to the calibration of the Jindalee Operational Radar Network (JORN). Verification of the successful deployment and stability of the large HF antenna is critical to the success of the mission. A bespoke deployable optics payload has been developed by DSTG to fulfil the dual purpose of direct verification of the deployed state of the HF antenna and capturing images of the Earth through a rotatable, dual-surfaced mirror and a variable-focus liquid lens. The payload advances research at DSTG in several fields of space engineering, including deployable mechanisms, precision actuation devices, radiation-tolerant electronics, advanced metal polishing and optical metrology. This paper discusses the payload design, material selection, trade-offs considered for the deployable optics payload and preliminary test results.

Mitigating Contamination with Nanostructure-Enabled Ultraclean Storage.

Airborne hydrocarbon contamination hinders nanomanufacturing, limits characterization techniques, and generates controversies regarding fundamental studies of advanced materials; consequently, we urgently need effective and scalable clean storage techniques. In this work, we propose an approach to clean storage using an ultraclean nanotextured storage medium as a getter. Experiments show that our proposed approach can maintain surface cleanliness for more than 1 week and can even passively clean initially contaminated samples during storage. We theoretically analyzed the contaminant adsorption-desorption process with different values of storage medium surface roughness, and our model predictions showed good agreement with experiments for smooth, nanotextured, and hierarchically textured surfaces, providing guidelines for the design of future clean storage systems. The proposed strategy offers a promising approach for portable and cost-effective storage systems that minimize hydrocarbon contamination in applications requiring clean surfaces, including nanofabrication, device storage and transportation, and advanced metrology.

Freeform digital twin approach to develop the HP 300 freeform verification standard

Inspired by previous experience in freeform metrology practice and industrial needs, the Czech Metrology Institute developed the freeform standard Hyperbolic paraboloid 300 of dimensions 300mm×300mm×160mm with a freeform functional area of approximately 64000mm2. The paper presents a mathematical–metrological approach to finding a suitable strategy for calibrating the freeform standard on a coordinate measuring machine with a tactile probing system. The calibration strategy consists in the development of a freeform digital twin of the standard, i.e. a continuous digital representation of a freeform measured value with associated uncertainty. A procedure to estimate the uncertainty of the coordinate freeform measurement is described, too. After calibration, the Hyperbolic paraboloid 300 standard will become a verification gauge suitable for use as a precision reference in advanced freeform metrology similar to common verification gauges widely used in length metrology.

Effects of growth temperature on structural and electrical properties of in-rich InAlN–GaN heterostructures by radio-frequency metal–organic molecular beam epitaxy

In-rich InAlN is a promising nitride semiconductor alloy for high-efficiency solar cells and wide-range light-emitting diodes due to its tunable bandgap from 0.7 to 6.2 eV. However, incomplete characterization has led to inconsistent fundamental properties in some studies. The aim of this study was to comprehensively investigate the structural, optical, and electrical properties of In-rich InAlN films grown on GaN/Al2O3 templates by RF-MOMBE at various temperatures. The methodology involved state-of-the-art metrology techniques, such as high-resolution x-ray diffraction (HRXRD), scanning electron microscopy (FE-SEM), Hall effect measurements, and transmission electron microscopy (TEM). The results showed that all InxAl1-xN films were epitaxially grown on the GaN/Al2O3 template, with the indium composition (x) decreasing with increasing growth temperature. Furthermore, phase separation of the In-rich InAlN films occurred at high growth temperatures(>550 °C), resulting in a relatively smooth surface. The optical absorption method measured the band-gap of the InxAl1-xN films, which ranged from 1.7 to 1.9 eV for x values between 0.77 and 0.91. The mobility and carrier concentrations of all In-rich InAlN films were measured at ∼60−277 cm2 V−1-s−1 and 2–7 × 1019 cm3 in the growth temperature of range 450 °C–610 °C, respectively. In conclusion, our comprehensive characterization using advanced metrology methods provides valuable insights into the properties of In-rich InAlN films, which can inform future optimization of these materials for various applications.

Infrared thermotransmittance-based temperature field measurements in semitransparent media.

Contactless temperature field measurements in or at the surfaces of semitransparent media are a scientific challenge as classical thermography techniques based on proper material emission cannot be used. In this work, an alternative method using infrared thermotransmittance for contactless temperature imaging is proposed. To overcome the weakness of the measured signal, a lock-in acquisition chain is developed and an imaging demodulation technique is used to retrieve the phase and amplitude of the thermotransmitted signal. These measurements, combined with an analytical model, enable the estimation of the thermal diffusivity and conductivity of an infrared semitransparent insulator (wafer of Borofloat 33 glass) and the monochromatic thermotransmittance coefficient at 3.3 µm. The obtained temperature fields are in good agreement with the model, and a detection limit of ±2 °C is estimated with this method. The results of this work open new opportunities in the development of advanced thermal metrology for semitransparent media.