Search Results (150)

Advances in artificial intelligence, high-performance computing, and generative AI technologies have driven a rapid increase in the memory bandwidth and data throughput required of semiconductor systems, establishing High Bandwidth Memory (HBM)—which vertically stacks multiple DRAM dies—as a key enabling memory technology. However, increasing the stack count and shrinking the interconnect pitch in HBM not only intensify vertical heat accumulation and hotspot formation but also give rise to complex reliability issues, including thermo-mechanical stress arising from coefficient-of-thermal-expansion (CTE) mismatch, package warpage, interfacial delamination, Cu protrusion, void formation, and joint degradation. This review analyzes the heat-generation and heat-transfer mechanisms of HBM packages and examines package-level thermal management strategies based on thermal interface materials, underfill, non-conductive film, epoxy molding compound, heat spreaders, and high-thermal-conductivity composites. It further summarizes the current crowding, electromigration, Cu–dielectric interfacial defects, and thermo-mechanical failure mechanisms that arise at fine-pitch interconnects and hybrid-bonding interfaces, together with the material and process design strategies developed to mitigate them. In addition, structure-based thermal management technologies—thermal TSVs, embedded cooling, and hybrid bonding—are compared. This review emphasizes that the thermal bottlenecks and reliability degradation of HBM are interconnected through interfacial thermal resistance, interfacial adhesion, residual stress, and interfacial defects, and proposes that next-generation, highly stacked HBM requires a multi-scale thermal-reliability co-design that integrally controls the heat-, stress-, and current-transfer pathways across the entire package and interconnect domain, rather than relying on the improvement of individual material properties alone. Full article

The electromigration (EM) reliability of line-type Sn-3.0Ag-0.5Cu (SAC305) solder joints with surface finishes of organic solderability preservatives (OSP), electroless nickel/electroless palladium/immersion Gold (ENEPIG), and Electroplated Ni was systematically investigated under a current density of 1.0 × 10⁴ A/cm² at 150 °C. In the as-soldered state, scallop-shaped Cu₆Sn₅ grains formed at both interfaces of the OSP joints. In contrast, driven by the Cu-Ni interaction, (Cu,Ni)₆Sn₅ grains formed at both interfaces in the ENEPIG and Electroplated Ni joints, with their morphology varying with Ni content and exhibiting polyhedral, prismatic, or scallop-like shapes. When the surface finishes served as the cathode, the failure rate of the OSP joints (100%) was 1.2 times that of the ENEPIG joints (83%) and 2.0 times that of the Electroplated Ni joints (50%). Extensive dissolution of the Cu substrate caused the rapid failure of the OSP joints, whereas both Ni-P and Ni layers effectively blocked the diffusion of Cu atoms. In the ENEPIG joints, the consumption of Ni atoms transformed the amorphous Ni-P layer into a porous Ni₃P layer, leading to joint failure. Electroplated Ni possesses a more stable crystalline structure and stronger atomic bonding, so more energy is required to release Ni atoms, resulting in a slower dissolution rate. Compared with the OSP joints, the EM lifetimes of the ENEPIG joints and Electroplated Ni joints were improved by 30% and 53%, respectively. Full article

The negative differential resistance (NDR) effect provides nonlinear control over ionic current and has important potential in ion sensing and information storage. A multiphys-ics numerical model is established using COMSOL Multiphysics 6.3, coupling the Poisson−Nernst−Planck and Navier−Stokes equations to investigate the effects of solution concentration gradient, pore length, pore diameter, and surface charge density on NDR effect. The results indicate that the NDR effect occurs only in the negative voltage range, where concentration gradient diffusion competes with electric field driven migration. The characteristic voltage window stabilizes between −0.2 V and −0.5 V, and the total current reaches a local extremum near −0.2 V. Electromigration dominates in this range and sup-presses Cl⁻ ion diffusion, while K⁺ transport is less affected, resulting in decreased total ionic current. Under baseline conditions, the total current decreases by 26.19%, from −0.42 nA to −0.31 nA. Increasing the concentration gradient, shortening the pore length, enlarging the pore diameter, and reducing the surface charge density enhance local vortices or maintain Cl⁻ diffusion pathways, thereby strengthening NDR characteristics. This study reveals the regulation mechanisms of NDR effect by solution conditions, macropore structures, and surface properties, providing theoretical guidance for tunable ionic current devices. Full article

Bias Temperature Instability (BTI) remains one of the principal reliability challenges limiting advanced CMOS technologies. Although degradation is commonly described by an empirical power–law relationship, the power–law exponent is generally regarded only as a fitting parameter used for lifetime extrapolation. This Perspective reexamines a previously published Multiple-Temperature Operational Life (MTOL) dataset to investigate whether the measured exponent contains previously overlooked physical information. Individual ring oscillators stressed under identical voltage and temperature conditions exhibit substantially different, yet reproducible, power–law exponents. When these measurements are analyzed over a broader temperature range, the apparent statistical scatter reveals a systematic kinetic dependence that produces a remarkably consistent lifetime relationship after incorporating the experimentally measured exponent into the Arrhenius analysis. The resulting intrinsic activation energy is significantly smaller than values obtained using conventional extrapolation methods, suggesting that part of the apparent activation energy arises from neglecting the temperature dependence of the degradation exponent. A recently proposed thermodynamic formulation based on Gibbs free energy and correlation entropy is presented as one possible physical interpretation of these observations, in which the power–law exponent reflects the correlation between successive degradation events rather than merely an empirical fitting constant. More generally, this Perspective suggests that the power–law exponent should be regarded as a measurable kinetic quantity whose systematic variation may provide additional insight into degradation mechanisms in BTI and other reliability phenomena. Full article

Dapagliflozin (DAPA), a selective sodium–glucose cotransporter 2 inhibitor, is widely used in the management of type 2 diabetes mellitus, with additional indications in heart failure and chronic kidney disease. The growing analytical demand for DAPA determination in pharmaceutical formulations, fixed-dose combinations, and biological matrices has stimulated the development of diverse analytical methods. This review provides a comprehensive evaluation of reported techniques for DAPA quantification in different matrices. Approaches discussed include chromatographic methods (TLC, RP-HPLC, UHPLC, LC-MS/MS), electromigration techniques (CE), and spectroscopic methods (UV–Vis, spectrofluorimetry). Emphasis is placed on key performance characteristics such as selectivity, sensitivity, linearity, robustness, and applicability to stability studies and bioanalysis. Recent trends, including the application of Quality by Design, green analytical chemistry principles, and advanced hyphenated techniques, are also addressed. While RP-HPLC remains widely used for routine quality control due to its robustness and accessibility, LC-MS/MS is generally regarded as the method of choice for trace-level bioanalysis owing to its superior sensitivity and selectivity. CE and spectroscopic techniques offer cost-effective and environmentally friendly alternatives, though with certain limitations. This review highlights current methodological gaps and outlines future directions for developing more sensitive and sustainable analytical strategies. Full article

Empirical power-law relationships are widely used in reliability physics to describe degradation kinetics and predict lifetime. Such behavior appears across diverse failure mechanisms, including time-dependent dielectric breakdown (TDDB), hot-carrier injection (HCI), bias temperature instability (BTI), electromigration (EM), and fatigue. In this work, a thermodynamic framework for reliability kinetics is developed from Gibbs free energy and entropy partitioning, leading to a generalized kinetic equation that incorporates thermal activation, stress acceleration, and accumulated degradation. The formulation introduces two parameters: a stress coefficient, $\gamma$, which describes the influence of externally applied stress, and a correlation coefficient, $\chi$, which describes how accumulated degradation influences subsequent degradation. Negative values of $\chi$ correspond to self-limiting evolution, positive values correspond to self-amplifying evolution, and $\chi =0$ represents statistically independent accumulation. Representative reliability mechanisms are interpreted within this framework, with TDDB approaching independent evolution, HCI exhibiting weak self-limiting behavior, BTI showing strong self-limiting behavior, and fatigue exhibiting self-amplifying behavior. Electromigration illustrates the complementary role of stress acceleration through $\gamma$. The proposed framework provides a common thermodynamic interpretation of empirical power-law degradation kinetics and introduces degradation correlation as a complementary descriptor for reliability modeling and lifetime prediction. Full article

Severe Cu and Pb enrichment in loess areas of northwestern China, mainly associated with mining and smelting activities, has increased the demand for efficient soil decontamination. Electrokinetic (EK) remediation is a promising in situ technology because it can drive ionic contaminants through low-permeability porous media with limited excavation and relatively low secondary disturbance. In this study, the effects of electric field strength, electrode type, and catholyte pH on Cu and Pb removal from contaminated loess were systematically evaluated using a large-scale EK reactor. The full name of EKG is electrokinetic geosynthetics. During treatment, pH, electrical conductivity, electric current, cumulative electroosmotic flow (EOF), and the spatial distributions of Cu and Pb were monitored. Increasing the electric field from 1.0 to 2.0 V cm⁻¹ increased current and EOF and accelerated anodic acid-front propagation, but it also strengthened cathodic alkalization and precipitation. Compared with graphite electrodes, electrokinetic geosynthetics (EKG) electrodes maintained higher current and EOF, generated stronger acidification, and increased Cu and Pb removal by approximately 25% and 5%, respectively. Among the tested catholyte conditions, pH 7.0 provided the best balance between electromigration and electroosmosis, achieving overall soil-phase removal efficiencies of approximately 19.0% for Cu and 8.0% for Pb. These results show that coordinated regulation of the electric field, electrode architecture, and electrolyte chemistry can mitigate the focusing effect in loess, although further enhancement is still required for field-scale decontamination. Full article

Research in the analytical and preparative fields of separation science has a long-standing tradition in the Czech Republic and former Czechoslovakia. Czech and Slovak scientists recognized the advantages of the two most widely used separation techniques, i.e., chromatography and electrophoresis, soon after their discovery and broader adoption. Their contributions to the development of the fundamentals and applications of chromatography and electrophoresis are demonstrated not only by numerous publications in renowned scientific journals and books, but also by several breakthrough innovations that led to patents and sometimes also to successful commercialization. The contributions of the earlier most prominent Czech scientists to the development of separation sciences have already been summarized in the literature. In the following lines, we instead aim to highlight less well-known, yet important, contributions within the Czech chromatographic and electrophoretic community. Moreover, recent developments since the last comprehensive reviews are covered in greater depth. Full article

This paper presents the electromigration (EM) performance of an embedded trace redistribution layer (ETR) in which the Cu trace features a rounded-bottom cross-sectional geometry and is encapsulated by a Ti barrier layer except for the top surface, with an optional top-side Ti cap. The ETR (with and without top-side Ti capping) and the conventional semi-additive-process (SAP) redistribution layer (RDL) are comparatively evaluated in terms of EM reliability. The ETR demonstrates a marked lifetime improvement compared with the SAP RDL. Notably, the Ti-capped ETR exhibits a minimal resistance increase in less than 10% even after a test duration of 4000 h. We discuss the key contributing factors and underlying mechanisms that support these improvements. Transmission electron microscopy (TEM) combined with atomic-percentage mapping confirms the effectiveness of Ti capping as a Cu diffusion barrier, showing continuous Ti coverage and no observable Cu diffusion. Electro-thermal simulations co-locate predicted thermal hot spots with experimentally observed open-failure sites, highlighting temperature-driven EM acceleration and the necessity of a barrier to suppress Cu–polymer interfacial oxidation. Stress simulations, together with EM failure analysis, indicate that the rounded-bottom Cu geometry alleviates local stress concentration and stress gradients, thereby creating conditions favorable for enhanced EM resistance. Full article

Electrokinetic remediation (EKR) was evaluated in naturally contaminated vineyard soils to assess copper redistribution, treatment redistribution efficiency, and changes in copper fractions across contrasting soil pH conditions. Ten vineyard soils (five acidic, five alkaline) were subjected to a 30-day ex situ EKR experiment under a constant electric field. Total copper content was measured in the anode, cathode, and inter-electrode zones, while copper fractions were quantified only in electrode zones exhibiting the most pronounced post-remediation decrease in total copper. The findings demonstrate that the EKR process generated distinct, soil-type-dependent gradients in copper mobility. In acidic soils, copper exhibited pronounced central-zone accumulation with notable depletion toward the anode, whereas in alkaline soils, the lowest concentrations consistently occurred near the cathode and increased toward the anode. Notably, one slightly alkaline soil displayed the highest redistribution efficiency (43.0%), underscoring the strong influence of soil chemistry on EKR performance. Redistribution efficiencies averaged 29.5% in acidic soils and 12.8% in alkaline soils, although localized acidification enabled notably higher redistribution in highly contaminated samples. These trends reflected on copper fractions: acidic soils showed enhanced release from Fe/Mn oxides and carbonates, while alkaline soils experienced stronger short-term mobilization driven by cation competition and dissolution of less stable oxide phases. Fractionation results indicated that the Fe/Mn oxide-bound fraction was the most susceptible to electromigration, while both acidic and alkaline soils ultimately shifted copper toward less extractable operational fractions. Full article

High-frequency 5G/6G communications demand copper foils combining sub-micron surface roughness (R_z < 0.6 μm) to minimize the skin effect with (111)-preferred orientation (for electromigration resistance), a balance challenging to achieve in conventional electrodeposition. This study quantifies the synergistic mechanism of a systematic series of additive formulations—from unary sodium 3-mercapto-1-propanesulfonate (MPS) to a quaternary MPS + polyethylene glycol (PEG) + Cl⁻ + gelatin (GEL) formulation—using electrochemical and microstructural analyses. While the ternary MPS + PEG + Cl⁻ system induced severe surface roughening (R_q = 449.5 nm) due to competitive adsorption, the introduction of high-concentration gelatin induced a kinetic bifurcation. It established a distinct “High-N/Low-D” regime—characterized by a 10⁴-fold reduction in diffusion coupled with a 10³-fold enhancement in nucleation, effectively suppressing the growth, reducing roughness from ~449.5 nm to ~81.3 nm via robust steric hindrance. However, this isotropic suppression simultaneously inhibited preferential crystal growth, leading to texture randomization. These findings kinetically quantify the intrinsic trade-off between extreme surface planarization and crystallographic orientation, providing a theoretical framework for designing high-performance interconnect materials. Full article

Direct-current (DC) electrokinetics in microfluidic channels is inherently affected by Faradaic reactions at the electrode–electrolyte interfaces, which induce local changes in pH and conductivity and, consequently, alter particle behavior. In this work, we present a simple microfluidic T-junction device designed to mitigate these effects by continuously flushing the regions near the electrodes with fresh electrolyte, thereby preserving the physicochemical properties of the main channel. Using fluorescence imaging with a pH-sensitive dye and electrical resistance measurements, we demonstrate that electrolyte acidification caused by water electrolysis can be effectively suppressed when advection overcomes electromigration of H⁺ ions. Order-of-magnitude estimates based on ion transport reveal that this condition is achieved when the flow velocity exceeds the characteristic electromigration velocity. We further investigate the effect of Faradaic reactions on cross-stream particle migration in electrophoresis experiments by quantifying the separation between suspended particles and the channel walls. We find that the particle–wall separation is significantly larger when electrolyte modifications are suppressed, clearly demonstrating the influence of Faradaic reactions on this phenomenon. Our results show that minimizing electrolyte modifications leads to a significantly enhanced particle-wall separation, highlighting the strong influence of Faradaic reactions on electrokinetic outcomes. These findings emphasize the importance of controlling electrochemical effects in DC electrokinetics and provide a simple and robust strategy to improve the accuracy and reproducibility of microfluidic electrophoresis experiments. Full article

With the ongoing miniaturization of solder joints in three-dimensional integrated electronic packaging, electromigration reliability has become a pressing concern. This study systematically examines the interfacial intermetallic compound (IMC) growth behavior of Cu/Sn-58Bi/Cu joint under electromigration (EM) with a symmetrical square-wave alternating current (AC). Electron backscatter diffraction (EBSD) was employed to perform statistical spatial analysis of Sn grain orientations within the joints to reveal the growth mechanism of interfacial IMC. Results demonstrate that the AC field markedly enhances the anisotropy of IMC growth in Cu/Sn-58Bi/Cu joints, exhibiting two phenomena: uniform growth on both sides and rapid growth (polar growth) on one side of the interfacial IMC. Among them, the IMC thickness difference characterization quantity Δ_IMC reached as high as 45.56% for the latter. This is attributed to the directional regulation of atomic migration rate by Sn grain orientation (the angle θ between the c-axis and the electron flow) and is further amplified by the altered atomic diffusion pathways imposed by the Bi phase distribution. Specifically, the Sn grains exhibit a pronounced preferential orientation mode along the current path (horizontal direction), with an orientation gradient of 0.915 μm⁻¹. The arrangement of Bi-rich phases alters the distribution of Sn grains in Cu/Sn-58Bi/Cu joints, thereby reshaping the internal electron transport pathways and significantly intensifying the orientation-dependent effect of IMC growth. Moreover, Sn grains adjacent to the Bi-rich phase boundaries (phase boundary grains) display a stronger tendency for c-axis orientation parallel to the current direction, exhibiting an average effective orientation parameter 1.948 times greater than that of bulk grains, which establishes a well-defined spatial orientation gradient. Full article

This study systematically investigates the influence of Bi content on the electromigration (EM) lifetime of low-temperature Cu/Sn-xBi-1Ag (600 μm)/Cu interconnects, where x = 57, 47 and 40 wt.%. The intrinsically higher product of diffusivity and effective charge number (DZ*) for Bi compared to Sn drives pronounced preferential migration of Bi atoms towards the anode, resulting in progressive β-Sn/Bi phase separation and linear thickening of a Bi-rich layer at the anode. Reducing the Bi content suppresses the EM-induced atomic flux (J_EM) through three principal mechanisms: (i) a decrease in the atomic concentration of mobile Bi atoms; (ii) a reduction in electrical resistivity that weakens the electron wind force; and (iii) an increase in lattice diffusion distance that lowers the effective diffusion coefficient (D_eff). The suppression of J_EM directly governs the thickening kinetics of anodic Bi layer, as evidenced by the close agreement between the calculated (1:0.40:0.23) and measured (1:0.45:0.26) anodic Bi layer growth rate ratios. Consequently, the EM lifetime is significantly extended from 62.3 h (Sn-57Bi-1Ag) to 164.9 h (Sn-47Bi-1Ag) and 414.1 h (Sn-40Bi-1Ag), representing 2.6-fold and 6.6-fold improvements, respectively. This study highlights that reducing the Bi content is an effective strategy for enhancing the EM reliability of Sn-Bi-Ag solder interconnects. Full article

Electromigration (EM) presents a major reliability challenge in advanced electronic packaging as device scaling and rising power demands lead to higher current densities in solder joints. While eutectic Sn-58Bi solder is widely adopted as a low-temperature alternative for its energy efficiency and compatibility with heat-sensitive substrates, its heterogeneous microstructure renders it vulnerable to EM-induced degradation. This review summarizes recent progress in understanding the EM behavior of Sn-Bi solder joints. We first introduce lifetime prediction models based on Black’s law, emphasizing the influences of current density, Joule heating, and thermomigration. Subsequently, the microstructural mechanisms accelerating degradation, including phase segregation and the coarsening of intermetallic compounds (IMCs), are examined. Various alloying strategies are evaluated for their effectiveness in strengthening the solder matrix and suppressing atomic diffusion to improve EM resistance. The critical role of substrate metallization is also discussed, comparing how different surface finishes affect interfacial reactions and joint lifetimes. Additionally, operational methods such as current polarity reversal are explored as potential pathways to mitigate degradation. Finally, we conclude that the EM reliability of Sn-Bi solder joints depends on the combined effects of alloy chemistry, interfacial reactions, and operating conditions, and we suggest future research directions in advanced modeling and material design for next-generation electronic applications. Full article