Search Results (184)

With the growing adoption of 3D stacked memory structures, precise alignment and overlay control have become critical for multi-layer overlay accuracy. The metrology accuracy and stability of alignment marks are crucial to ensuring optimal alignment and overlay performance. This study systematically investigates the contributions of two key alignment parameters—Wafer Quality (WQ) and Alignment Position Deviation (APD)—to the alignment model residue in 3D structures. Through experimental and simulation approaches, we analyze the interplay between WQ, APD and overlay performance. Results reveal that APD exhibits a stronger correlation with uncorrectable model residue, particularly under global process variations such as etch non-uniformity. Furthermore, APD sensitivity varies directionally (X/Y direction marks) and spatially (wafer edge versus center), highlighting the need for targeted mark designs in process-sensitive zones. These findings provide actionable insights for optimizing alignment strategies, mark designs and process monitoring throughout R&D, technology development and high-volume manufacturing phases. Full article

This study aims to evaluate the effect of adding a chitosan/perlite (Ch/P) carrier to anaerobic digestion (AD) on the efficiency and kinetics of the process, as well as the directional changes in the bacterial microbiome. A carrier with this composition was applied in the AD process for the first time. A laboratory experiment using wafer waste (WF) and cheese (CE) waste was conducted under mesophilic conditions. The analysis of physico-chemical properties confirmed the suitability of the tested carrier material for anaerobic digestion. Both components influenced the microstructural characteristics of the carrier: perlite contributed to the development of specific surface area, while chitosan determined the porosity of the system. Using next-generation sequencing (NGS), the study examined how the additive affected the genetic diversity of bacterial communities. Fourier-transform infrared spectroscopy (FTIR) revealed that the degradation rate depended on both the carrier and the substrate type. Consequently, the presence of the carrier led to an increase in the volume of biogas and methane produced. The volume of methane for the wafer waste (WF–control) increased from 351.72 m³ Mg⁻¹ (VS) to 410.74 m³ Mg⁻¹ (VS), while for the cosubstrate sample (wafer and cheese, WFC–control), it increased from 476.84 m³ Mg⁻¹ (VS) to 588.55 m³ Mg⁻¹ (VS). Full article

We developed the Global–Local Integrated Topology inverse design algorithm (denoted as the GLINT algorithm), which employs a trajectory-based optimization strategy with waveguide–substrate material-flipping structural modifications, enabling the direct optimization of discrete waveguide–substrate binary structures. Compared to the conventional Direct Binary Search (DBS), the GLINT algorithm not only significantly enhances computational efficiency through its global search–local refinement framework but also achieves a superior 20 nm × 20 nm optimization resolution while maintaining its optimization speed—substantially advancing the design capability. Utilizing this algorithm, we designed and experimentally demonstrated a 3.5 µm × 3.5 µm dual-port wavelength division multiplexer (WDM), achieving a minimum crosstalk of −11.3 dB and a 2 µm × 2 µm 90-degree bending waveguide exhibiting a 0.31–0.52 dB insertion loss over the 1528–1600 nm wavelength range, both fabricated on silicon-on-insulator (SOI) wafers. Additionally, a 4.5 µm × 4.5 µm three-port WDM structure was also designed and simulated, demonstrating crosstalk as low as −36.5 dB. Full article

Three-dimensional (3D) printing has emerged as a transformative technology in dental splint fabrication, offering significant advancements in customization, production speed, material efficiency, and patient comfort. This comprehensive review synthesizes the current literature on the clinical use, benefits, limitations, and future directions of 3D-printed dental splints across various disciplines, including prosthodontics, orthodontics, oral surgery, and restorative dentistry. Key 3D printing technologies such as stereolithography (SLA), digital light processing (DLP), and material jetting are discussed, along with the properties of contemporary photopolymer resins used in splint fabrication. Evidence indicates that while 3D-printed splints generally meet ISO standards for flexural strength and wear resistance, their mechanical properties are often 15–30% lower than those of heat-cured PMMA in head-to-head tests (flexural strength range 50–100 MPa vs. PMMA 100–130 MPa), and study-to-study variability is high. Some reports even show significantly reduced hardness and fatigue resistance in certain resins, underscoring material-specific heterogeneity. Clinical applications reviewed include occlusal stabilization for bruxism and temporomandibular disorders, surgical wafers for orthognathic procedures, orthodontic retainers, and endodontic guides. While current limitations include material aging, post-processing complexity, and variability in long-term outcomes, ongoing innovations—such as flexible resins, multi-material printing, and AI-driven design—hold promise for broader adoption. The review concludes with evidence-based clinical recommendations and identifies critical research gaps, particularly regarding long-term durability, pediatric applications, and quality control standards. This review supports the growing role of 3D printing as an efficient and versatile tool for delivering high-quality splint therapy in modern dental practice. Full article

Color centers in solids, such as nitrogen-vacancy (NV) centers in diamonds, have gained significant attention in recent years due to their exceptional properties for quantum sensing. In this work, we demonstrate an NV center-based temperature sensor integrated into an optical waveguide to enable internal temperature sensing. A surface-cladding optical waveguide was fabricated in a diamond wafer containing NV centers using femtosecond laser direct writing. By analyzing the resonant peaks of optically detected magnetic resonance (ODMR) spectra, we established a precise correlation between temperature changes induced by the pump laser and shifts in the ODMR peak positions. This approach enabled temperature monitoring with a sensitivity of 1.1 $\mathrm{mK}/\sqrt{\mathrm{Hz}}$. These results highlight the significant potential of color centers in solids for non-contact, micro-scale temperature monitoring. Full article

Wafer testing is a crucial process used to test dies before packaging. In recent years, the process has undergone significant changes to reduce costs and ensure sufficient test coverage while preserving ATE and die integrity. The process is associated with substantial expenses and consumes considerable time. In this paper, we aim to provide an overview of the current state of wafer testing and highlight the most critical aspects of this type of testing. This paper will discuss the direction of the industry in this sector by highlighting the potential critical issues introduced by the current technological limits when implementing future technologies such as denser pad layout and multi-site testing. The results of our work will consider the area occupation of the probe head, the number of springs, the multi-site wafer testing approach, and the pad layout on a die. To evaluate the impact of choices such as the choice of pitch and ratio, and the use of technologies such as the arrangement of matrix pads or the use of multi-site probe heads as precisely as possible, a dedicated tool has been developed and used for the calculation of new metrics and indices, such as the horizon, and all the graphs reported in this work. Full article

This paper presents an in situ time-based sensor designed to provide process authentication. The proposed sensor leverages the inherent metal routing within the chip to measure the RC time-constants of interconnects. However, since the routing metal is typically designed to minimize resistance and capacitance, the resulting small RC time-constants pose a challenge for direct measurement. To overcome this challenge, a “three-configuration” measurement approach is introduced, incorporating two auxiliary components—poly resistor and metal-insulator-metal (MIM) capacitor—to generate three amplified RC time-constants and, subsequently, deduce the routing time-constant. Compared to directly measuring the routing time-constants, this approach reduces measurement error by over 82% while incurring only a 25% area penalty. A straightforward analytical model is presented, taking into account the impact of parasitic capacitances within the discharge path. This analytical model exhibits an excellent concurrence with simulated results, with a maximum difference of only 2.6% observed across all three configurations and a 3.2% variation in the derived routing time-constant. A set of five variants of the time-based sensor are realized using a 130 nm CMOS process. Each variant consists of 44 samples distributed across 11 dies on two wafers. To verify the precision of the proposed sensor, identical resistors and capacitors are fabricated alongside them, forming a direct measurement array (DMA) that is measured using external equipment. After adjusting the routing resistance and capacitance values in the simulations to correspond to the mean values obtained from the DMA measurements, the proposed sensor’s measured results demonstrate a close alignment with simulations, exhibiting a maximum error of only 6.1%. Full article

As the linewidth of semiconductor nanostructures continues to decrease, the criteria for acceptable surface homogeneity of silicon (Si) epi-films are becoming increasingly stringent. To address this challenge, the effect of different tilted ceiling heights on the Si epi thickness homogeneity in an atmospheric pressure chemical vapor deposition (APCVD) reactor is investigated numerically. In this study, the deposition temperature on the wafer is controlled at 1373 K. When a tilted ceiling with decreasing height along the streamwise direction is used, the average gas mixture velocity increases with the streamwise direction, which can reduce the impact of flow distortion caused by the rotation of the susceptor. At the same time, the growth of the reaction boundary layer on the wafer is suppressed, which helps with the diffusion of trichlorosilane (TCS) on the wafer surface. This makes the drop in the TCS concentration along the streamwise direction more linear, thereby improving the linearity of the growth rate on the wafer surface along the streamwise direction. Therefore, the present results for a reactor without an inlet plate show that the thickness homogeneity across the entire surface of the wafer after a complete susceptor rotation can be significantly improved by linearly reducing the ceiling height in the streamwise direction. A further increase in the inclination of the inclined ceiling leads to a further improvement in the deposition homogeneity. However, the growth rate values at the same position perpendicular to the streamwise direction are inconsistent, which is not conducive to deposition homogeneity. This shortcoming can be improved upon by using a four-inlet plate reactor with an inclined top plate and by properly selecting the position of each partition and the inlet gas mixture velocity of each inlet channel, thereby greatly increasing the deposition homogeneity of the Si epi-layer. For the cases considered in this study, the deposition thickness non-homogeneity across the wafer surface decreased from 38% to 3%. Full article

Non-hydrogenated diamond-like carbon (DLC) films and molybdenum-doped diamond-like carbon (Mo-DLC) films were deposited by direct current magnetron sputtering. The formation was carried out on Si (100) wafers. The influence of molybdenum concentration and deposition temperature on the surface morphology, chemical composition, type of chemical bonds, friction force at nanoscale, and nanohardness of the DLC coatings were investigated by atomic force microscopy (AFM), energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and nanoindenter, respectively. The concentration of molybdenum in the films varies from 1.2 at.% to 10.3 at.%. The increase in molybdenum content promotes the graphitization of DLC films, lowering the sp³ site fraction and increasing the oxygen content, which contributes to the reduction in nanohardness (by 21%) of the DLC films. The decrease in the synthesis temperature from 235 °C to 180 °C enhanced the oxygen amount up to 20.4 at.%. The sp³ site fraction and nanohardness of the Mo-DLC films were enhanced with the reduction in the deposition temperature. The film deposited at a substrate temperature of 235 °C exhibited the lowest friction coefficient (CoF) of 0.03, where its molybdenum concentration was 1.2 at.%. The decline in the synthesis temperature increased the CoF of the Mo-DLC films up to seven times. Full article

Electronic packaging can transform the chip to a device for assembly. Soldering and bonding are important procedures in the process of electronic packaging. The continuous development of packaging architecture has driven the emergence of improved soldering and bonding processes. At the same time, conventional soldering and bonding processes are still widely used in device packaging. This paper introduces two kinds of technologies in wafer bonding, direct and indirect, expounds on five kinds of die attachment processes, and also describes the process of ball bonding and wedge bonding in wire bonding in detail. Flip chip bonding and methods for making bumps are also described in depth. Bump bonding processes are vital for 3D-SiP packages, and the bonding technology of copper bumps is a research hotspot in the field of advanced packaging. The surface mount technology and sealing technology used in some electronic devices are also briefly introduced. This paper provides insights for researchers studying soldering and bonding in contemporary electronic device packaging. Full article

The influence of pH on silicon dioxide direct bonding is studied, unveiling its role in bonding energy enhancement. We show that the deposition of basic salt or molecules consistently increases the silicon dioxide adherence energy. The underlying mechanisms, including silica hydrolysis and catalysis of siloxane bond formation, are explored. The results offer valuable insights into optimized direct bonding processes for microelectronics and related applications. Full article

Silicon materials have been widely investigated as anode materials for lithium-ion batteries. However, they are typically processed as fine powders into composite electrodes. Towards potentially repurposing silicon wafers as battery anodes, in this work, the impacts of the laser ablation of silicon wafers on electrochemical cycling outcomes were investigated. Both pristine wafers and laser-ablated wafers were assessed, where the silicon anodes were paired with all-active material LiCoO₂ cathodes to assess the system as lithium-ion full cells. The laser ablation process modified the surface morphology of the silicon wafers, creating a polycrystalline silicon layer with increased surface area. Electrochemical cycling revealed that the laser-treated wafers demonstrated higher capacity retention and improved rate capability compared to untreated wafers, especially when discharged at the highest current density of 7 mA cm⁻². This work demonstrated the improvements in electrochemical outcomes with the direct use of silicon wafers as lithium-ion anodes when laser ablation surface treatment is applied. Full article

The growing volume of end-of-life photovoltaic (PV) panels, projected to reach 60–78 million tons by 2050, poses significant environmental challenges. With landfilling being the most cost-effective but unsustainable disposal method, developing eco-friendly processes to recover valuable materials is essential. One potential solution for recovering raw materials from PV panels is thermal treatment. Therefore, in this study, PV modules were heat-treated at a low heating rate, and their components were manually separated with an average efficiency of 90%. The recovered silicon wafers and tempered glass sheets were utilized to fabricate new PV panels using lamination technology. The applied heating parameters enabled the cells to be removed from the PV panels without structural damage. However, the results of electroluminescence tests showed that thermal treatment significantly damages the p-n junctions, rendering direct reuse in new panels unfeasible. The thermal separation methods outlined in this study offer valuable opportunities for industries employing various PV-panel-recycling technologies. These methods lay the groundwork for environmentally responsible management and recovery of materials from end-of-life solar panels, advancing sustainable recycling practices. Full article

This paper presents a comprehensive review of advancements in wafer-level packaging (WLP) technology, with a particular focus on its application in surface acoustic wave (SAW) and bulk acoustic wave (BAW) filters. As wireless communication systems continue to evolve, there is an increasing demand for higher performance and miniaturization, which has made acoustic wave devices—especially SAW and BAW filters—crucial components in the Radio Frequency (RF) front-end systems of mobile devices. This review explores key developments in WLP technology, emphasizing novel materials, innovative structures, and advanced modeling techniques that have enabled the miniaturization and enhanced functionality of these filters. Additionally, the paper discusses the role of WLP in addressing challenges related to size reduction and integration, facilitating the creation of multi-functional devices with low manufacturing costs and high precision. Finally, it highlights the opportunities and future directions of WLP technology in the context of next-generation wireless communication standards. Full article

Backside alignment is a key microfabrication process step, especially in micro-electromechanical systems (MEMS). The double-side mask aligners used for this purpose are unaffordable for many research centres. We propose a new method that aligns the backside mask to the features on the topside using a direct laser writer, which is available in many cleanrooms. In this method, the corner co-ordinates of the sample are used as alignment features, and a transformation matrix is developed to map the design co-ordinates to the stage co-ordinates. This method has been validated on copper features as small as 100 $\mathsf{\mu }$m on silicon substrates. Test samples are cut from a 2 inch Si wafer, and copper features are sputtered and developed onto the topside. Backside patterns that are aligned to these copper features are created using photolithography through the application of this alignment method. This method exhibited challenges for samples without sharp right-angled corners, where the estimation of the corner co-ordinates resulted in misalignment. Sixteen areas over nine samples were analysed. An average alignment resolution of 23 ± 1 $\mathsf{\mu }$m was established in the x and 8 ± 4 $\mathsf{\mu }$m in the y direction, and a rotation misalignment of less than 1° was achieved. Differences in alignment were due to the individual quality of each sample’s corners and to the clarity of the corner co-ordinates. This new approach provides a route towards low-cost microfabrication process development. Full article