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The high-volume manufacturing of the next generation of semiconductor devices requires state-of-the-art statistical analyses to reduce measurement uncertainties. Prediction intervals can characterize the reliability of the predictive performance of regression models. Normalized conformal prediction is a mathematically motivated approach to find distribution-free prediction intervals which depends on skillful modeling to evaluate a regression model fit to training data, and quantile regression is a classical and widely applied guideline to devise prediction intervals. Noise levels impact the reliability of line edge roughness estimates from noisy scanning electron microscope images. We propose procedures to generate prediction intervals based on image denoising and other image processing techniques and demonstrate significant improvements over earlier methods developed for the deep convolutional neural network EDGENet. [ABSTRACT FROM AUTHOR]

Turn-off failure under clamped inductive load, is one of the most concerns in insulated gate bipolar transistor (IGBT) chips. Besides, this turn-off failure can be attributed to two causes, i.e., the dynamic latch-up and the secondary breakdown. Despite great simulation work investigated previously, the experimental research should be further focused. Up to now, the typical features and differences for these two turn-off failures still remain unclear. In this article, two failures’ waveforms are first compared in experiment. Moreover, their internal current, electric field, and temperature distributions are compared by simulation in detail. Then, two different failure features, focusing on the failure cell structures, are summarized from the scanning electron microscope (SEM) results for the first time. The marked signatures of these failures, such as the current filament path and the mixture region, are further analyzed in this article. According to the SEM results, the lateral and vertical current paths can be observed in dynamic latch-up chip and secondary breakdown chip, respectively. These failure signatures in waveforms and SEM results can contribute to the distinguished method to the failure causes in IGBT device, and enhance the chip's performance more effectively. [ABSTRACT FROM AUTHOR]

A high gain, wide bandwidth (BW), and low-profile $D$ -band magnetoelectric dipole antenna-in-package (AiP) is proposed in this article. The unit antenna with a cavity backed slot is first evaluated by a substrate integrated waveguide (SIW) feed structure. The simulated impedance BW of the unit antenna covers 27 GHz from 132 to 159 GHz with stable broadside radiation patterns. Then, a $4\times $ 2 array based on the proposed unit antenna is designed and verified on a four layer BT-based organic substrate. The array design is composed of an isolation, a $2\times $ 2 subarray, a two-way SIW power divider, and a probe pad to SIW transition. The $2\times $ 2 subarray is realized by a four-way broad wall coupler with a V-junction design in particular. Tested by probing on substrate in the direct far-field chamber, the measured impedance BW covers 23.4 GHz from 135.4 to 158.8 GHz with a peak gain of 14.1 dBi at 150 GHz. The average of measured gains within the 130–160-GHz band is 12 dBi. Modeled with the dimensions of structural analysis results from optical microscope (OM) and cross-sectional scanning electron microscope (SEM) inspection, the post-simulation result shows a good agreement with the measurement result, including impedance BW, radiation patterns, and gains. This article demonstrates that the proposed AiP using the low-cost BT-based substrate manufacturing technology can be a good candidate for the future $D$ -band applications. [ABSTRACT FROM AUTHOR]

The long-term operation of dry-type transformer bushings at high temperatures can impact the performance of their primary insulation material. This article presents an experimental study of the effect of thermal aging time on electrical treeing in the epoxy resin-impregnated paper. The experimental results show that the electrical treeing pattern along the middle path of the electric field and the interlayer creepage along the average direction of the electric field are closely related to the aging time. Under the effect of thermal aging at 150 °C, the tree-starting voltage of epoxy resin-impregnated paper tends to increase and decrease as the aging time increases. An analysis and discussion of the test results in conjunction with scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) tests suggest that the destruction of the cross-linked network of the epoxy resin-impregnated paper at 150 °C is a fundamental reason for the significant decrease in the material’s tree-starting voltage and the change in electrical treeing morphology and interlayer creepage. Long-term operation at high temperatures can seriously impact the primary insulation performance of dry-type transformer bushings and requires attention. [ABSTRACT FROM AUTHOR]

The concentration of glucose was detected using an H-terminated diamond solution-gate field-effect transistor (H-diamond SGFET). The linker molecular 1-pyrenebutyric acid–N-hydroxy succinimide ester (Pyr-NHS) was introduced to modify the H-diamond surface. Then, glucose oxidase (GOD) was immobilized on the diamond surface by linker Pyr-NHS. Atomic force microscope and scanning electron microscope measurements confirmed the successful immobilization of Pyr-NHS and GOD enzyme on the H-diamond surface. The concentration of glucose was determined by the shift of gate voltage (${V}_{\text {GS}}$) in transfer characteristics of H-diamond SGFET. Also, the sensitivity of sensor for glucose detection was obtained as −58.69 mV/ ${\text {log}}_{{10}}$ (glucose concentration) by the slope of fitting curve, which represented the relationship between ${\Delta {V}}_{\text {GS}}$ and logarithmic of glucose with concentration increasing from 1 $\times 10^{-{3}}$ to 1 M. The reusability of device was characterized by the transfer properties and small standard deviation (SD) of maximum output current (${I}_{\text {DS(max)}}$) in four tests, indicating excellent reusability for detection of glucose. [ABSTRACT FROM AUTHOR]

Alignment between the reference layout (or target pattern) and the corresponding scanning electron microscope (SEM) image is a crucial task for the die-to-database (D2DB) inspection in the semiconductor industry. However, it is challenging to align them accurately because the style and quality of reference layouts represented as a computer-aided design (CAD) are quite different from those of grayscale SEM images with noise. Direct application of conventional cross-correlation-based matching methods often leads to misalignment. Here, we propose a new method enabling the precise pattern alignment. The main idea is to transform SEM images into target-like CAD images using a generative adversarial network (GAN). As the generated and real layout images have similar style and quality, they can be precisely aligned using conventional matching methods. Then, the SEM image can be located correctly on the corresponding reference layout for inspection. A polygon-based clustering algorithm for target patterns is developed to avoid manual selection and minimize the number of training data. [ABSTRACT FROM AUTHOR]

Improving the tracking and erosion resistance of silicone rubber (SiR) is of great significance to outdoor SiR insulators. In this work, a feasible method to enhance the antitracking performance of SiR by a ceramifiable system is investigated. Through scanning electron microscope (SEM), energy dispersive spectrometer (EDS), X-ray diffraction (XRD), and other characterization methods, the mechanism that aluminum hydroxide (ATH) and low-melting glass (LMG) powder synergistically improve the tracking resistance of SiR is proposed. In this ceramifiable system, ATH plays a role in absorbing heat and serves as a precursor under the synergy with LMG, which promotes the formulation of dense mullite ceramic layer on the surface of SiR at the high temperature generated by dry band arc discharges, thereby the internal SiR is protected from degradation. Hydrophobicity and mechanical properties of ATH/LMG/SiR composites are also investigated, revealing that ATH/LMG improves the mechanical properties and hydrophobicity compared with one filler filled with the same amount. The ceramifiable system exhibits a good effect that the antitracking performance, mechanical properties, and hydrophobicity of SiR composites are improved at the same time. This system provides a new method for the research of antitracking SiR materials applied in outdoor SiR insulators. [ABSTRACT FROM AUTHOR]

In our study, the dye-sensitized solar cells (DSSCs) with double-layer thin films were fabricated. The active bottom layer of the structure was mainly made of the commercially available titanium dioxide (TiO2) nanoparticles. TiO2 hollow microspheres (THS) were doped into the TiO2 composite material and used as the scattering top layer. The THS prepared by the one-pot hydrothermal method was composed of irregularly arranged nanoparticles. Meanwhile, we also characterized the synthesized hollow TiO2 microspheres by both the scanning electron microscope (FE-SEM) and the X-ray diffractometer (XRD). Besides, we produced DSSCs with different weight percentages (0.5wt%, 1wt%, and 2wt%) of THS photoanodes. The DSSCs based on pure TiO2 showed the short-circuit current (JSC) of 8.33 mA/cm2 and the photovoltaic conversion efficiency (PCE) of 3.75%. The DSSCs manufactured using 1wt%-THS photoanode had JSC of 12.02 mA/cm2 and a PCE of 5.01%. When compared with the JSC and PCE based on pure TiO2 DSSCs, a significant improvement in the structure was observed. [ABSTRACT FROM AUTHOR]

Silicon oxynitride (SiOxNy) is a common barrier material in thin-film encapsulation (TFE) organic light-emitting diode (OLED). Substrate defects, voids and film internal defects occur during SiOxNy deposition process and result in poor film conformity and barrier failure. In this work, a mathematical model is built to evaluate experimental deposition rate and a high accuracy two dimensional model is proposed to predict the SiOxNy thin film profile evolution on arbitrary substrate in plasma enhanced chemical vapor deposition (PECVD) process. Based on level set method, image processing algorithm, iterative algorithm and velocity extension algorithm are proposed to ensure the high accuracy simulation. A series of design of experiments (DOEs) of SiOxNy film deposition are conducted to validate the model. For numerical deposition rate, the model predicted value fits the experimental data quite well and the offset in between has a root-mean-square error of 2.33%. For film’s cross section profile, satisfactory agreement between model and scanning electron microscope (SEM) image is obtained, we use the step coverage as quantitative index for film uniformity, and the index’s prediction errors are all less than 4%. [ABSTRACT FROM AUTHOR]

Short circuit failure mode (SCFM) of integrated gate commutated thyristor (IGCT) under extreme failure is of vital importance in high voltage direct current power transmission based on modular multilevel converter technology. Due to the sealing housing package of IGCT, the short circuit mechanism is hard to be clarified. Considering this limitation, the current density changes in IGCT with different failure modes are studied under different current levels in a built integrated test system with the placed magnetic sensor array and thermal couple array. Then, the short circuit mechanism of failed IGCT is proposed based on the experimental results. IGCT with turn-off failure performs self-triggering effect due to the focused short current and increased temperature in the initial destruction area, which is usually located in a single position of the outer cathode rings. While IGCT with surge current failure shares the short current among multiple initial destruction areas, which are usually distributed evenly in the wafer area. Scanning electron microscope picture and energy dispersive X-Ray spectroscopy (EDX) analysis show that the formed conducting alloy has spread into the molybdenum plate deeply and the phenomenon of atom diffusion (molybdenum, silicon and aluminum) near the interface is observed. Finally, long term short circuit tests of more than 12 h with both turn-off failure and surge current failure under 3000 A prove the stable SCFM of IGCT. [ABSTRACT FROM AUTHOR]

Bulk acoustic wave (BAW) filter with large bandwidth is an urgent need in fifth-generation (5G) communication systems. In the present work, 43° Y-cut lithium niobate (LN) single-crystal film is prepared on multilayer oxide film, and bulk acoustic filter with oxide Bragg reflector (BR) is successfully achieved. The design method of the filter and the fabrication process are presented. Atomic force microscope (AFM) and scanning electron microscope (SEM) are used to characterize the quality of thin films. The results demonstrate the feasibility of transferring single-crystal film onto multilayer oxide, which is efficient for the confinement of acoustic energy. The resonator has effective electromechanical coupling coefficient of 14.6% and figure of merit (FOM) of 32.94. The filter with a compact size of 600 $\mu \text{m}\,\,\times 400\,\,\mu \text{m}$ has a relative bandwidth of 10.3% at a center frequency of 3.128 GHz, which is promising for the application of 5G systems. [ABSTRACT FROM AUTHOR]

In a typical nitrogen glow discharge plasma, a large number of energetic neutrals, N2, are generated inside the cathode sheath. In this work, we are presenting a technique for the extraction of this energetic N2 for the treatment of starch. The energetic neutrals N2 were generated by the application of −500 V on a transparent cathode. On reaching the cathode, N2+ ions are absorbed; however, it is transparent to energetic N2 neutrals molecules generated inside the sheath by charge exchange collisions, as the energetic N2 neutrals are unaffected by the electric field and pass through the transparent cathode. The sample for treatment was placed below the transparent cathode and thus exposed to the energetic N2 neutrals extracted from glow discharge plasma for a duration of 30 min. The impact of energetic N2 neutral extracted from glow discharge plasma results in modification of physical and thermal properties of corn starch (maize starch). The physicochemical and morphological properties of treated and untreated samples were studied. The surface roughness of the plasma-treated corn starch increased significantly in comparison to the untreated sample. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) spectra confirmed that there is a considerable reduction in the semicrystalline nature and the polymer structure morphology of the corn starch. Scanning electron microscope (SEM) micrographs of samples show a substantial change in surface morphology and in size of the grains between the plasma-treated and untreated corn starch samples. The room-temperature thermal properties of the plasma-treated corn starch samples are measured using differential scanning calorimetry (DSC). The results confirm that the starch treated with energetic N2 molecules has a lower gelatinization temperature and could be applied in food processing industries. [ABSTRACT FROM AUTHOR]

This contribution presents the results of a study of the germination rate and growth parameters of wheat seeds after atmospheric pressure surface coplanar dielectric barrier discharge (DBD) plasma treatment. The germination rate and biometric parameters such as the root, shoot length, mass of the seedlings, and the $\alpha $ -amylase enzyme activity were studied at different plasma exposure time. The seed coat surface wettability and morphology were determined by apparent contact angle measurement and scanning electron microscope (SEM) analysis. Seed surface disinfection and the presence of filamentous fungi have also been investigated at different discharge parameters. It is shown that the optimal plasma treatment duration for increasing the growth parameters and enhancing the enzymatic activity is 5–15 s. It was found that the longer plasma exposure requires complete sterilization of the seed surface from pathogens, compared to the optimal treatment time for high germination. Based on the obtained results, the possible mechanisms of the positive effect of plasma treatment on the enhanced germination of wheat seeds are discussed. [ABSTRACT FROM AUTHOR]

The purpose of this work is to study the dielectric charging of polymer fibers with the electron plasma charging effects accompanied by the emergence of waves propagating along the polymer fiber surface. Monitoring of the charge propagation along the single fiber has been performed using dielectric polyhydroxybutyrate (PHB) fibers obtained by the electrospinning (ESP) method under the electron beam inside the scanning electron microscope chamber. The mechanical effect of the electron beam on the polymer fibers has been detected in a time-lapse mode. The influence of the polymer surface irregularities and mechanical defects on the fiber charging has been demonstrated. Plasma mechanism is typical not only for electrophysical phenomena but also for the control of mechanical movement of the fibers by the electron beam and the charge propagation during electron-beam-induced melting and in the presence of hydrodynamic polymer flows. It is assumed that the mechanical effect in the methods using an electron beam (and plasma on the dielectric surface) as an impact source can be determined by the following factors: pressure of the electron beam and the electric field, contribution of the secondary emission, thermal/thermomechanical factors, and dynamic balance or competition between all the forces affecting the sample (electron-beam pressure, gravity pressure, recoil pressure during evaporation, vapor pressure/surface tension, and so on). In addition to purely scientific interest, the above phenomena are also of significant applied interest since the influence of the polymer fiber charging on the separation procedure of aerosols in nonwoven filters is well known, and hence, charging of such polymer fibers is important for some energy storage devices. [ABSTRACT FROM AUTHOR]

In this work, vertical micromirrors that are fabricated using deep etching of silicon followed by metal sputtering are studied. Physical parameter extraction methodology, image processing, machine learning and discrete element analysis are used to extend the easy-to-take scanning electron microscope images into 3-D topographical information, that are usually obtained using atomic force microscope and transmission electron microscope. The experimental results show that vertical micromirrors surface quality has a granular nature showing degraded performance and a different optical response with respect to the bulk metal. A physical model is developed and validated by comparing the measured reflectivity of the fabricated micromirrors with a multi-layer reflectivity optical model based on the effective medium theory fed by the extracted physical parameters. In agreement with the experimental results, the model predicts a reflectivity of about 60 % for a sputtered aluminum thickness of 50 nm, compared to 97.5% reflectivity predicted by the bulk metal model. [2021-0154] [ABSTRACT FROM AUTHOR]

Three sets of bottom-gate (BG) nanocrystalline silicon (nc-Si:H) thin-film transistors (TFTs) with amorphous silicon nitride (a-SiNx:H) as the gate dielectric were produced under various nc-Si:H plasma deposition conditions. Chromium (Cr) and aluminum (Al) were used as the gate electrodes in each TFT set. The effects of the gate electrode on the nc-Si:H TFT performance, particularly on its electrical stability, were studied. For each TFT set, Al-gated TFTs resulted in the higher mobility, lower subthreshold slope, and better stability compared to the Cr-gated TFTs. The impact of the Cr- or Al-gate underlayer on the surface and bulk properties of a-SiNx:H and nc-Si:H films was analyzed in detail considering back channel etching (BCE) characteristics, electrical, scanning electron microscope (SEM), Raman, grazing angle X-ray diffraction (GAXRD), and Fourier transform infrared-attenuated total reflection (FTIR-ATR) measurements. Structural differences were recognized in a-SiNx:H and nc-Si:H films grown in the BG TFT sequence depending on the type of the gate electrode. Based on these findings, possible reasons were proposed to explain the superiority of the Al over Cr as the gate electrode for nc-Si:H TFTs. [ABSTRACT FROM AUTHOR]

This study investigates the damage characteristics and mechanism of the crystalline regions of cross-linked polyethylene (XLPE) in water tree propagation. XLPE cable samples are subjected to an accelerated water tree aging at a voltage of 7.5 kV/400 Hz for 240, 480 and 720 hours. After the water tree aging, the crystalline structural changes of the water tree samples are observed by X-ray diffraction (XRD). In addition, the water tree samples are eroded and the morphologies of the crystalline regions in water tree regions are observed by a scanning electron microscope (SEM). The XRD results show that the crystallinities of the aged samples decrease with aging, especially after 240 hours. The SEM results show that after 240 hours of aging, slip lines and dislocation steps emerge on the fracture surfaces. After 480 hours, microcracks with sizes of several micrometers are observed in the directions of the crystal faces. After 720 hours, conical dislocation pits appear in the samples and there are microvoids at the bottoms of the pits. Based on the XRD and SEM results, it is concluded that the crystalline regions of XLPE are damaged in the water tree aging. At last, the initiation process of the dislocations and the damage characteristics of the crystalline regions in the water tree propagation are discussed. [ABSTRACT FROM AUTHOR]

Different combinations of metal thin films were investigated as metal interconnect for miniaturized microelectromechanical system (MEMS) encapsulation with stable electrical properties and sealing capability. The candidates of metal as the adhesion layer include Cr, Ti, and Ta. Metals Pt and Pd are the selection for the diffusion barrier layer. Comparison results of adhesion tests, stress measurements, and aging tests show that the interconnect of Ti-Pd-Au has the best stability in MEMS devices. After the screening process, the analyses of scanning acoustic tomography (SAT), scanning electron microscope (SEM), and pull test verify that the symmetric and ultrathin Ti-Pd-Au structure can be bonded well for the sealing process. Furthermore, the plasma treatment was conducted to reduce the thermal budget of encapsulation. The reliability tests present the bonding scheme with plasma treatment can withstand rapid temperature variation and high moisture for a long duration. All the results show that the interconnect of Ti-Pd-Au simultaneously used in the sealable encapsulation has a great potential for advanced miniaturized MEMS packaging. [ABSTRACT FROM AUTHOR]

This study proposed a nonenzymatic sensor for lactic acid detection based on copper doped zinc oxide (CZO) modified by graphitic carbon nitride (g-C3N4) and iron–platinum nanoparticles (FePt NPs). The silver paste electrodes of the sensor were prepared using screen printing technology, and the CZO sensing film was deposited using radio frequency (R.F.) sputtering system. The g-C3N4 nanosheet solution was prepared through liquid exfoliating of the g-C3N4 in water. The sensing film was modified by adding different contents of the FePt NPs in g-C3N4 solution. The various concentrations of the FePt NPs were 0.03, 0.1, and 0.3 wt%. The ${V}$ – ${T}$ measurement system was applied to investigate the sensing characteristics of the lactic acid sensors based on CZO sensing film modified by g-C3N4 and FePt NPs. The surface morphology of the sensor was analyzed by scanning electron microscope (SEM), X-ray diffraction (XRD), and dynamic light scattering (DLS). In this work, the 0.1 wt% FePt NPs-g-C3N4 lactic acid sensor has the best sensitivity, linearity, response time, and the limit of detection (LOD). [ABSTRACT FROM AUTHOR]

Several fluorinated polyethylene surface studies have proved that the fluorination reaction can effectively prevent charge from being injected into polyethylene. Therefore, this paper explores the influence of fluorinated electrode on space charge behavior in polyethylene. In this study, the space charge distribution inside polyethylene is measured by laser-PWP (Pressure Wave Propagation) method while altering electrode fluorination duration and fluorination temperature. The experimental results show that measured homocharge injection is increased in polyethylene to which a fluorinated semiconductive electrode is heat pressed. Attenuated Total Reflectance-Infrared (ATR-IR) spectroscopy and Scanning Electron Microscope (SEM) are also performed, revealing that the fluorinated layer of semiconductive electrode on the interface between polyethylene and electrode block impurities from entering polyethylene. The measured space charge distribution, being the planar average amount, also reveals impurity generation since heterocharge formation is observed. As such impurities are blocked, in the meantime the electrodes' homocharge injection remains un-affected, thereby the measured apparent charge is greatly increased. [ABSTRACT FROM AUTHOR]

Gas discharge tube (GDT) breaks down discharge with surge overvoltage during long-term use. Notably, there is a risk of short-circuit failure due to the drop in insulation resistance after a certain number of discharges, which might be mainly caused by cumulative discharge. This article builds a cumulative discharge experiment platform to analyze the failure mechanism, performed the GDT whole life cycle cumulative discharge experiment and focused on the change law of its insulation resistance and breakdown voltage. For samples that are short-circuited, X-ray observation and vibration testing perpendicular to the GDT axis are conducted to examine the internal micro-morphology without damaging their external structure. The GDT is opened and its internal structure and material properties of the GDT cavity are compared and analyzed by scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) methods. The results indicated that the insulation resistance of GDT continuously decreased by several orders of magnitude in the last 10% of the life cycle, and the insulation resistance before failure is generally less than 1 $\text{k}\Omega $. Through X-ray observation of the short-circuit failure sample, two different abnormal growth phenomena in the cavity are found, including flocs between the electrodes and deposits on the tube wall. Further analysis and experiments demonstrated that the flocs between the electrodes and the deposits on the tube wall are the primary factors causing the degradation of GDT insulation performance. The formation mechanism of the two short-circuit modes is explained by the difference in the splash angle and mode of metal particles of different sizes on the electrode surface. [ABSTRACT FROM AUTHOR]

We present the fabrication and evaluation of a microchannel with thin Si windows and a trapping structure for injected liquid samples, including an evaluation using tubing methods of polydimethylsiloxane eyelets, and Kovar. Yeast cells and latex particles were observed using a fluorescence microscope under atmospheric conditions and a scanning electron microscope (SEM) under vacuum. As moving and flowing liquid samples cannot be observed for a long time, a trapping structure in the microchannel is required. In our experiment using pole structures under a thin Si window in microchannels to trap liquid samples, we successfully observed them using the SEM under an accelerating voltage of 15 kV and an emission current of 75 μA. This result indicates the possibility of using higher accelerating voltages of electrons for higher observation resolutions at a lower power density of 2.3 kW/cm2. Microfluidic channels with a thin window would be a useful technique for monitoring liquid samples under vacuum. [2020-0367] [ABSTRACT FROM AUTHOR]

Deep Learning approaches have revolutionized in the past decade the field of Computer Vision and, as a consequence, they are having a major impact in Industry 4.0 applications like automatic defect classification. Nevertheless, additional data, beside the image/video itself, is typically never exploited in a defect classification module: this aspect, given the abundance of data in data-intensive manufacturing environments (like semiconductor manufacturing) represents a missed opportunity. In this work we present a use case related to Scanning Electron Microscope (SEM) images where we exploit a Bayesian approach to improve defect classification. We validate our approach on a real-world case study and by employing modern Deep Learning architectures for classification. [ABSTRACT FROM AUTHOR]

In this paper, an artificial accelerated aging platform of Fiber Reinforced Plastic (FRP) core rod with various aging conditions, including high temperature, acid corrosion and high electric field strength, is presented. Based on that, the typical degradation characteristic of FRP core rods in decay-like fracture insulators are simulated and verified. A thermal infrared imager is used to detect the temperature rise when the AC voltage is applied. The results show that the temperature of the FRP specimens under multiple stresses is significantly increased up to 61 °C (177%) compared with the specimen under single aging stress (22 °C). Moreover, Scanning Electron Microscope (SEM), Fourier Transform Infrared (FTIR) Spectroscopy, X-ray Photoelectron Spectroscopy (XPS) and Thermal Gravimetric Analysis (TGA) are applied to study the physicochemical properties of the aging FRP specimen and the reaction occurred in the degradation process and the influence mechanism among different aging factors. The results show that the epoxy resin matrix is eroded by water and nitric acid. In the presence of a high electric field, the epoxy resin matrix is further degraded and evaporated. Then the interface between the epoxy resin and the glass fiber separates and develops, accompanied by ion-exchange and hydrolysis process. With the development of the degradation process of FRP core rod, obvious carbonized channel can be detected. Finally, electric erosion puncture occurs and breakdown happens. Compared with the FRP core rod extracted from the decay-like fractured composite insulators, the artificial accelerated aging sample shows the similar change trend on physicochemical properties. This work can provide theoretical support for the FRP core rod degradation mechanism and life predicting of high voltage composite insulators or other actual operation environment. [ABSTRACT FROM AUTHOR]

Scanning electron microscope (SEM) images of molecular sieve catalysts contain information about the shapes and sizes of these particles. SEM image measurement is a crucial step in the evaluation of the catalytic performances. Instance segmentation methods, such as Mask R-CNN, are effective in automatically analyzing SEM images. However, their performance is limited in small datasets. Although overfitting caused by small datasets can be addressed through data augmentation at the image level, the application of Mask R-CNN still needs further improvement for generalization enhancement. In this article, two techniques for Mask R-CNN are proposed to alleviate overfitting during the training on small datasets. First, merged sampling on the region proposal network simultaneously samples proposals with high and low scores in order that the head networks can be exposed to more diverse proposal samples. Second, random proposal expansion enhances the diversity of samples provided to the mask branch of Mask R-CNN. These two techniques can be viewed as data augmentation at the instance level. Experiments on a small SEM image dataset showed that merged-sampling Mask R-CNN with random proposal expansion improved about the average precision (AP) by 5%, compared with the original Mask R-CNN. Overfitting on the small dataset is effectively controlled using the proposed methods. Hence, the results of the particle measurements of the industrial SEM images improved. [ABSTRACT FROM AUTHOR]

An ultrasonic testing method was used to detect the fretting wear behavior of electrical connectors. The specimens used in this study were contacts of type-M round two-pin electrical connectors. The experiments consisted of running a series of vibration tests at different combined stress levels of frequencies and accelerations. During each experiment, through an electrical connector fretting wear ultrasonic detection device, the energy attenuation of ultrasound was monitored as a characteristic parameter, which is induced by the wear debris generated by the fretting wear of electrical connectors. The results show that vibration frequency, vibration acceleration, and vibration cycles all have a positive cumulative effect on debris generation on the contact surface of contacts. There is more debris accumulated in the root area of contact pins. The fretting surface is examined using a scanning electron microscope (SEM) and energy dispersive spectrometer (EDS) analysis to assess the surface profile, the extent of fretting damage, and elemental distribution across the contact zone, and the observed results are basically consistent with the ultrasonic test results. [ABSTRACT FROM AUTHOR]

A novel way to implement integrated metal–insulator–metal (MIM) capacitor with ultrahigh capacitance density of up to 5.621.8 nF/mm2 has been proposed earlier. This technology embeds 3-D MIM capacitor into the existing trench of through-silicon via (TSV) prior to Cu filling to achieve >90% planar surface area reduction. However, the previous study was on the early-stage test vehicles without Cu filling. In this work, complete test vehicles with fully filled Cu TSVs have been successfully fabricated whose trench diameters are 0 (D00), 10 (D10), 20 (D20), and 30 μm (D30), respectively. First, the design layout and the process flow are disclosed in detail. Then under scanning electron microscope (SEM) and transmission electron microscope (TEM), it is found that the peak of the Si scallop on the sidewall is deformed for the D30 test vehicle. For the first time, the damage is found in Si substrate, instead of TSV SiO2 liner, due to the thermomechanical stress between the TSV Cu core and the surrounding structures. In addition, the Al2O3 dielectric layer is also impaired at the damaged Si peaks. Finally, the leakage current density is measured and normalized at a bias of 1.5 V: 4 × 10−9 A/cm2 for D00, 4.1 × 10−8 A/cm2 for D10, 1.1 ×10−6 A/cm2for D20, and 7.4 × 10−1 A/cm2 for D30, respectively. Therefore, the structural integrity of the D10 and D20 test vehicles with fully filled Cu TSVs is preserved, but the D30 test vehicle is not intact due to higher stress. The capacitance density of 6.547.1 and 7.091.7 nF/mm2 is recorded for the D10 and D20 test vehicles, respectively. [ABSTRACT FROM AUTHOR]

Feature sizes in integrated circuits have decreased substantially over time, and it has become increasingly difficult to three-dimensionally image these complex circuits after fabrication. This can be important for process development, defect analysis, and detection of unexpected structures in externally sourced chips, among other applications. Here, we report on a non-destructive, tabletop approach that addresses this imaging problem through x-ray tomography, which we uniquely realize with an instrument that combines a scanning electron microscope (SEM) with a transition-edge sensor (TES) x-ray spectrometer. Our approach uses the highly focused SEM electron beam to generate a small x-ray generation region in a carefully designed target layer that is placed over the sample being tested. With the high collection efficiency and resolving power of a TES spectrometer, we can isolate x-rays generated in the target from background and trace their paths through regions of interest in the sample layers, providing information about the various materials along the x-ray paths through their attenuation functions. We have recently demonstrated our approach using a 240 Mo/Cu bilayer TES prototype instrument on a simplified test sample containing features with sizes of ~ 1 μm. Currently, we are designing and building a 3000 Mo/Au bilayer TES spectrometer upgrade, which is expected to improve the imaging speed by factor of up to 60 through a combination of increased detector number and detector speed. [ABSTRACT FROM AUTHOR]

We propose a deep learning-based data-driven framework consisting of two convolutional neural networks: 1) LithoNet that predicts the shape deformations on a circuit due to IC fabrication and 2) OPCNet that suggests IC layout corrections to compensate for such shape deformations. By learning the shape correspondences between pairs of layout design patterns and their scanning electron microscope (SEM) images of the product wafer thereof, given an IC layout pattern, LithoNet can mimic the fabrication process to predict its fabricated circuit shape. Furthermore, LithoNet can take the wafer fabrication parameters as a latent vector to model the parametric product variations that can be inspected on SEM images. Besides, traditional optical proximity correction (OPC) methods used to suggest a correction on a lithographic photomask is computationally expensive. Our proposed OPCNet mimics the OPC procedure and efficiently generates a corrected photomask by collaborating with LithoNet to examine if the shape of a fabricated circuit optimally matches its original layout design. As a result, the proposed LithoNet–OPCNet framework can not only predict the shape of a fabricated IC from its layout pattern but also suggests a layout correction according to the consistency between the predicted shape and the given layout. Experimental results with several benchmark layout patterns demonstrate the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

In modern integrated circuit (IC) packaging, it is difficult to perceive and evaluate the quality of the solder ball interconnections due to their complex hidden physical configuration and miniaturization. Laser ultrasonic inspection (LUI) technique is a novel, nondestructive, and noncontact method that has achieved great success in evaluating the quality of interconnections in chip-scale and ball-grid array (BGA) packages. In this article, an enhanced dual-fiber array LUI system is used to evaluate the quality of BGA solder balls in advanced industrial flip-chip BGA packages subjected to thermal cycling reliability tests. LUI results are validated with electrical testing, scanning electron microscope (SEM), and dye-and-pry results. LUI results are well correlated with the intermetallic compound cracks in BGA solder balls observed using SEM, and dye-and-pry. This study demonstrates the feasibility of using the LUI system for one of the modern IC packages and the potential to use the LUI system for future advanced IC packages such as 3-D packaging. [ABSTRACT FROM AUTHOR]

The article presents the results of a new method for electron detection at atmospheric pressure (APED). This method is developed for a MEMS (Micro-Electro-Mechanical System) electron microscope to obtain images of a sample placed on a silicon nitride membrane in air. The electron beam is transmitted through the membrane and, under specific conditions, can reach the detector despite the presence of air molecules. The experiments were carried out on a miniature electron optical microcolumn model consisting of an octupole deflector, an anode with a Si3N4 membrane, and an electron collector. The anode, glass spacer, and electron collector formed a microchamber that was filled with air. Measurements were made using an electron beam from JEOL Scanning Electron Microscope (SEM). The first images obtained using the APED method and a quantitative description of the operation principle are presented. [ABSTRACT FROM AUTHOR]

Series of exchange-coupled BaFe12O19 (BaM)/CoFe2O4 (CFO) and BaM/Co0.5Zn0.5Fe2O4 (CZFO) composites were synthesized using the autocombustion method. Effect of soft (CFO/CZFO) phase weight fraction on structural, magnetic, and microwave properties of composites has been investigated and compared. X-ray diffraction patterns and scanning electron microscope (SEM) micrographs confirmed the presence of BaM and CFO/CZFO phases with well-distinguished grains in the composites. Existence of interfacial coupling was verified by smooth demagnetization behavior and single peak in corresponding $\text{d}M/\text{d}H$ curves. Saturation magnetization ($M_{s}$) and coercivity showed strong dependence on exchange interactions between hard and soft magnetic spins. Compared to BaM, $M_{s}$ of composites were 22% and 36% higher with CFO and CZFO, respectively. Frequency-dependent complex permittivity ($\varepsilon$) and permeability ($\mu $) in ${\text{K}}_{u}$ -band were found to be dependent upon the relative composition and nature of soft phase. Maximum $\varepsilon $ of 45 and $\mu $ of 1.6 were achieved for BaM/CFO (50/50) composite. Exchange-coupled magnetodielectric with high $\varepsilon $ and $\mu $ were developed for various microwave applications. [ABSTRACT FROM AUTHOR]

Cold plasma (CP) has been acknowledged as a potential tool in enhancing the availability of bioactive compounds and antioxidant (AO) potential of plant products. Lotus is an ethno pharmacologically important herb with commercial applications in the food, beverage, and cosmetic industry. The bioactive constituents of the lotus flower are responsible for its medicinal and AO properties. This scrutiny identifies the influence of CP treatment on the bioactive compounds and AO potential of lotus petal powder (LPP). The petals were dried using a microwave drier, milled, and were treated in a low-pressure plasma system at 2.5 kV for 5 min. Physicochemical properties like color, total phenolics, flavonoids, and AO activity of the plasma-treated LPP were investigated and microstructure was evaluated with a scanning electron microscope. A notable increase in the flavonoid content was observed from 35.87 to 89.87 mg quercetin equivalent (QE)/100 g in the treated petal powder, while the phenolics content showed only a slight increment. The AO capacity also increased from 42.92 to 76.63 mg ascorbic acid equivalent (AAE)/100 g. The bioactive compounds were analyzed using gas chromatography–mass spectrometry/mass spectrometry (GC–MS/MS) and found that plasma treatment increased the relative percentage of phytosterols, amyrin, and nuciferine. This increment in the level of phytochemicals can be attributed to the leaching out of components from the stressed surface of LPP, relieving the potential of CP processing on improving the nutritional and health benefits. [ABSTRACT FROM AUTHOR]

We have successfully observed the process-induced microstructure of the ultrafine CoFeB–MgO-based magnetic tunnel junctions with a perpendicular easy axis (p-MTJs) down to junction size of less than 20 nm using scanning transmission electron microscope (STEM) tomography combined with energy-dispersive X-ray spectroscopy (EDX). This made it possible to examine 3-dimensionally the precise structural information inside the entire MTJ. By this, the root cause of the change in the resistance of the MTJ was found to be the altered region consisting of Fe-dipping attached to the edge of the MgO and ultrathin TaO layer uniformly formed on the MTJ surface. This altered region is caused by etching during patterning of the MTJ, and the resistance value of the MTJ changes depending on the degree of adhesion of insulating TaO and Fe atoms at the edge of the MgO barrier layer. Furthermore, it was found that the unevenness of the MgO/CoFeB interface inside the MTJ was not a factor that caused the change in the thickness of the MgO barrier layer in the current process. Our results show that STEM tomography is an effective tool for failure analysis to clarify the relationship between the detailed structure of fine MTJs and magnetic properties. Unlike the conventional cross-sectional STEM observation, since the STEM tomographic observation includes the whole view of the MTJ, this enables higher resolution observation as the MTJ size decreases without overlooking the cause of failure inside the MTJ. [ABSTRACT FROM AUTHOR]

The mapping of the current induced by a focused electron beam in a scanning electron microscope (SEM) has been used to localize electrically stressed regions in the AlGaN/GaN-on-Si Schottky barrier diode (SBD) structures cross-sectioned by the focused ion beam (FIB) technique. We have shown that homogeneously distributed electron beam induced current (EBIC) intensity detected below the Schottky contact at 0 V changes with increasing reverse voltage VR and peaks at the edges of a field-plate region. The build-up of local microavalanches at high electric voltages has been indicated by overexposed EBIC signal at areas following the edges of the field plate structure. Interpretation of EBIC measurements is supported by electro-physical modeling and simulations employing the 2-D finite element method in Synopsys TCAD Sentaurus. The simulations prove that the electric field intensity in the SBD locally reaches values sufficiently high to trigger multiplication of the excessive carriers generated by an electron beam, which helps one to visualize and localize critical regions in GaN-based power electronic devices by the EBIC method. [ABSTRACT FROM AUTHOR]

A study on the design, framework, experimental arrangement, data acquisition, and subsequent analysis of cold crack detection using fiber Bragg grating (FBG) sensors during welding is presented. Cold crack induced acoustic emission (AE) events are detected by multiple FBG sensor configurations and using a commercial FBG AE interrogation system. The crack locations are theoretically predicted using a method of linear localization based on the differences in the time of arrival of the AE events at different FBG sensors. The approach is experimentally validated by employing packaged and unpackaged FBG sensor arrays in a welding experiment with gas tungsten arc welding on ultrahigh toughness high hardness armor steel. Frequency analysis of the AE events is also carried out to understand the cold crack characteristics. The weld region of the steel plate is diced into 1-mm cross-sectional pieces, and the positions of the cold cracks are identified using scanning electron microscope imaging and then cross correlated with the measured AE events, and thereby confirming the correct identification of cold crack location using the FBG sensing method. [ABSTRACT FROM AUTHOR]

13-kV 4H-SiC MOSFETs were successfully fabricated on a 125-μm -thick epitaxial layer on 6-in, N+ SiC substrates. Both lateral and longitudinal straggles from the P-well implant were investigated to optimize the JFET width and thus to avoid channel pinching in the JFET region. Channel lengths and channel mobilities were varied to investigate the effect of channel portions in determining the ON-state resistance of the 13-kV MOSFETs. It was discovered that the low channel mobility limits the transconductance, such that the MOSFETs cannot offer full current at reasonable gate voltages (Vgs = ~ 20 V). Even in high voltage MOSFETs, it is essential to have a reasonably high channel mobility to reduce ON-state power loss. Therefore, channel design and process are also important aspects of high voltage devices. A superior blocking capability of 13.2 kV was demonstrated using a ring-based edge termination structure. It is important to note that the straggling effect due to ion implantations should also be taken into account when designing an edge termination structure. Static electrical characteristics, scanning electron microscope (SEM) imaging, secondary ion mass spectrometry (SIMS) analysis, and 2-D simulation of the 13-kV MOSFETs were employed to support this reasoning. [ABSTRACT FROM AUTHOR]

Transient liquid phase (TLP) bonding is a promising solution for high temperature (HT) electronic devices as high-quality bonds can be formed at a temperature much lower than the melting point of the resulted joint. In this work, Ag-rich Ag–Sn TLP bonding was evaluated as a potential die attach solution for HT (250 °C) electronic applications. The influence of varying the Ag content on the mechanical strength of the Ag–Sn TLP joint was investigated through room temperature (RT) and HT shear tests. The study was complemented with X-ray imaging of any void formation, and scanning electron microscope (SEM)/energy-dispersive X-ray spectroscopy (EDX) spectra for composition and morphology analysis. It is shown that the Ag-rich joint comprises Ag and Ag3Sn intermetallic compound (IMC), and no obvious void was observed. The shear strengths of the joints measured at both RT and 250 °C have satisfied the requirement for HT applications. In addition, the fractured surfaces after the shear test showed that the failure of Ag-rich joints occurred mostly in the Ag3Sn IMC region. Furthermore, the shear strength improved with increasing Ag content (up to 81.5 at.%) in the bond. [ABSTRACT FROM AUTHOR]

A frequency tunable vircator, which has the reflex triode geometry, was designed and experimentally tested. The cloth velvet was used as the cathode material. The planar and the Ernst-profiled velvet cathodes, which have diameters of 40, 50, 60, and 70 mm, were used in the experiments. The electric field strength values and the corresponding frequencies of the radiated microwave were measured and analyzed for each of the cathodes. The anode–cathode distances between 4 and 16 mm were swept in the experiments. The planar cathodes display larger electric field strength values, whereas the Ernst-profiled cathodes have wider frequency ranges. The characteristics of the velvet, such as tuft density and fiber dimensions, were investigated in detail using scanning electron microscope images. The condition of the vacuum was also observed during shots. [ABSTRACT FROM AUTHOR]

We report laser-based fault isolation methodologies for the localization of open and short failures in $1 \times 5\,\,\mu \text{m}$ via-last through-silicon via (TSV) structures for 3-D system-on-chip (SoC) integration. Due to the photosensitive TSV interconnect capacitance, observation of the photocapacitance response enables nondestructive localization of metallization ruptures. A light-induced capacitance alteration (LICA) measurement is demonstrated on an open failed $1 \times 5\,\,\mu \text{m}$ TSV chain structure with a manufacturing defect. We validate our measurements with active voltage contrast imaging in the scanning electron microscope (SEM) and focused-ion beam (FIB) cross sectioning. Second, TSV dielectric defects generating leakage current between TSV and substrate (i.e., short defects) are detected and localized by sensing the laser-induced TSV photocurrent. An optical beam-induced current (OBIC) measurement is demonstrated on electrically overstressed TSV array structures whereby multiple TSVs are configured in a parallel arrangement. By applying a selective substrate removal process, we can expose the full TSV array and perform optical and tilted SEM inspection and reveal pinhole defects in the TSV liner. We further investigate the effect of breakdown energy on the pinhole formation, relate electrical measurements to SEM inspection, and confirm our results by FIB cross sectioning. [ABSTRACT FROM AUTHOR]

The experimental results of dielectric barrier discharge (DBD) plasma treatment on barley (Hordeum Valgare L cv. Yusef) seed germination and seedling growth are analyzed and presented. The seeds were exposed to DBD plasma with 40-, 80-, and 120-W powers for 15 s. All treatments showed positive effects on seed germination, seedling growth, and vigor index. The scanning electron microscope (SEM) images and water imbibition evaluations of plasma-treated seeds revealed that the treatments improved water absorption in the seeds. Similar positive improvements were observed for the plasma-treated seeds in the seedling stage. The best germination characteristics were obtained in 80-W DBD plasma, which included an 18.28% increment in total germination percentage, and 13.35%, 66.83%, 38.55%, and 31.93% increment on the seed germination potential, vigor index, shoot height, and root length, respectively. Moreover, the seed germination of the plasma-treated barley was studied after 2, 7, 14, and 30 days of storage, which indicated the desirable effect of plasma over the storage time. It is concluded that the use of cold plasma can significantly improve the germination and seedling growth of barley seeds. [ABSTRACT FROM AUTHOR]

Scanning electron microscopy images are an attractive option to estimate the roughness of nanostructures. Convolutional neural network (CNN) based algorithms have improved scanning electron microscope (SEM) image denoising and estimation of line roughness measurements. However, these algorithms need improvements to run at high speeds with a low memory footprint and without compromising accuracy. We introduce two approaches to reduce computation time and memory. We first propose deep CNNs LineNet1 and LineNet2 to perform simultaneous denoising and edge estimation on rough line SEM images. This multiple task formulation in LineNet1 and LineNet2 reduces training time, inference time and model sizes. LineNet2 also facilitates edge estimation in the multiple-line images and generalizes the approach for other geometries. Our training method uses supervised learning datasets of single-line SEM images and multiple-line SEM images together with edge positions information. We next consider multiple visualization tools to improve our understanding of the LineNet1 architecture and use the resulting insights from these visualizations to motivate a study of two variations of LineNet1 with fewer neural network layers. One of these visualization techniques is new to the visualization of denoising CNNs. Our results show that these approaches significantly reduce the memory and computation needed for edge estimation with a slight impact on accuracy. [ABSTRACT FROM AUTHOR]

Filling epoxy resin in glass fibre fabric with surface modified nano-Al 2 O 3 as a means of increasing the dielectric strength is investigated in this work. The 50 Hz breakdown strength with 3 wt% nano-Al 2 O 3 is shown to be 10% higher than the neat epoxy/glass fibre material and 4% higher than the neat epoxy. An improved interface bonding between the glass fibre and the epoxy is evidenced by SEM characterization. Based on a multilayer dielectric model, it is found that introducing nano-Al 2 O 3 to the epoxy resin can efficiently alleviate the dielectric constant mismatch between the epoxy and the epoxy-integrated glass fibre layer, which results in an improvement in the dielectric strength. [ABSTRACT FROM AUTHOR]

During usage, printed electronic components are often stretched, bent, folded, and/or twisted to conform to underlying structure. In this article, tests have been developed for characterizing the mechanical and high-frequency electrical behavior of inkjet-printed patch antennas on flexible polyethylene terephthalate (PET) substrates under uniaxial and biaxial bending. A patch antenna is designed to have a single resonant frequency of 5 GHz in free space. Polycarbonate cylindrical mandrels of 1.25” diameter and special sculptured surfaces have been used as uniaxial and biaxial bending fixtures, respectively. Up to 2000 bending cycles have been performed in both uniaxial and biaxial bending tests. During bending tests, $S_{11}$ (return loss) has been measured by a vector network analyzer (VNA) in both bent and flat configurations. Mechanical simulations have also been performed to determine the strain distribution in the printed elements which will lead to changes in electrical behavior. Scanning electron microscope (SEM) images have been taken to examine the physical damage in the printed structure and to correlate with the strain values obtained through mechanical simulation. High-frequency electrical simulations have also been performed to correlate with the bending experimental data. It is seen that the conductivity of the printed structure changes differently in different zones, due to various values of strain they undergo. Although the cracks are observed in the printed structures, the maximum relative shift in the measured resonant frequency is less than 1.66% in both uniaxial and biaxial bend tests. [ABSTRACT FROM AUTHOR]

The raster scanning imaging mode is widely used in scanning electron microscopes (SEMs), transmission electron microscopes (TEM), and atomic force microscopes (AFM), and can achieve subatomic resolution. However, only a point on the shallow surface of an object can be imaged at one time using the raster scanning imaging mode, whereas the entire surface of the object can be imaged in the image plane once and instantaneously using the optical imaging mode, which is a parallel imaging mode. Therefore, the image distortion and blur for the scanning imaging mode are different from the optical imaging. In this paper, we propose a theory to describe the mechanism of the scanning imaging process and restore the degraded image (distorted and blurred image) obtained using an SEM. The theory consists of a scanning equation, motion or deformation equations, and an assumption called the intensity-invariant hypothesis. Numerical simulations of the scanning imaging process and restoration of the degraded images are performed using the scanning imaging formulas, spatial non-uniform point spread function, and inverse restoration algorithms, including algebraic, interpolation, and their hybrid methods to verify the feasibility of our theory. In situ experiments on uniform linear motion, uniaxial tensile, and fatigue were also conducted to demonstrate the validity and efficiency of the proposed scanning imaging theory and restoration methods. We anticipate that this imaging and restoration theory will enable the scanning imaging mode to be used in in situ dynamic imaging and for mechanical property measurement of materials. [ABSTRACT FROM AUTHOR]

The helical microstructure has been widely applied to various industries, including the mechanical manufacture, electronics, and biomedical engineering. Due to the miniature size of the helical microstructure, the low manufacture precision will highly degrade its working performance. Although current manufacture methods can realize its fabrication with relatively high accuracy, the used material is constrained to several specific conditions. To address the above problems, this article proposes a laconic and high-precision three-dimensional (3-D) manufacture method for the helical microstructure based on the microrobotic system without the limitation of materials. In this article, the microrobotic system with six degrees-of-freedom is developed for manufacture. Then, the image processing operation for providing feedback information is introduced. Third, the trajectory of each individual robotic module is designed according to the structure's certain size. After that, the control system with feedforward and double feedback is reported to realize the accurate manufacture. Finally, the experimental results demonstrate that the manufacture precision can reach up to 2  $\mu$ m with the standard deviation (STD) of 1.06. This research will pave a new path for the high-precision 3-D manufacturing at small scale, and have long-term impacts on robot-aided manufacturing system with high potential for commercialization in the future. [ABSTRACT FROM AUTHOR]

Commercial gallium nitride (GaN) high-electron-mobility transistors used for power electronics applications show superior performance compared to silicon (Si)-based transistors. Combined with an increased radiation hardening properties, they are key candidates for high-performance power systems in a harsh environment, such as space. However, for this purpose, it is key to know the potential failure mechanisms (FMs) of the devices in depth. Here, we demonstrate how the repeated thermomechanical stress in a power cycling (PC) test within specified operating conditions destroys the GaN device. Based on leakage current localization analysis, we identify an FM with a yet unknown root cause. Utilizing emission microscopy, focused ion beam cutting, and scanning electron microscope techniques, it is revealed that multilayer cracks of a GaN die are triggered by a commercial leading package structure, which shows excellent capability under frequent thermomechanical stress. Through multiphysics simulations, it is shown that the structural factors that lie behind the strong performing component properties inside the package ultimately are directly related to the failure pattern. This article is accompanied by a video demonstrating dynamic thermal distribution difference between thermography measured in a practical experiment and a multiphysics simulation result during a single PC of a PC test. This article is accompanied by a supplementary figures file demonstrating test environment, preparation process of specimens, and reverse engineering results for the simulation model. [ABSTRACT FROM AUTHOR]

In this work, we use a simplified version of Young’s solution for the steady-state Joule-heating, that uses temperature dependent thermal and electrical conductivities, to find the temperature and displacement behavior of a V-shaped electrothermal microactuator (ETMA) device. In order to test and validate our approach we performed FEM simulations and actually built an ETMA device by microfabrication. The experimental device displacement was measured in vacuum, with a scanning electron microscope. Our numerical results agree quite well with the FEM simulation and experimental results up to a displacement of (0.8 ± 0.2) $\mu \text{m}$ and applied current of 30 mA. Above 35 mA, an abrupt variation of the resistivity is observed followed by surface degradation at 50 mA and device melting at 52 mA. The validity of our approach is discussed of the device geometry and material parameters. [2019-0208] [ABSTRACT FROM AUTHOR]

This article deals with the reliability of a power semiconductor exposing to the severe thermal stresses. The importance of solder joint thickness on the power semiconductor's useful lifetime is demonstrated in this article. Solder layer thickness has knock on effects both on the creep accumulated strain and thermal characteristics of the power semiconductors. Since, these effects are in contradictory of each other, a trade-off seems to be essential to optimize the solder layer thickness. Thereby, thermo-mechanical behavior of a discrete power semiconductor under the thermal mission profile was simulated and the results were integrated to the actual conditions. The simulation results reveal that after thermal cycling, some creep strain is produced in the solder layer especially at the corners. The thinner the solder joint was, the greater accumulated creep strain was observed leading to the faster degradation. On the contrary, the thicker the solder layer was, the larger thermal resistance was observed leading to the higher junction temperature. Accordingly, the article is concentrated on optimizing the solder layer thickness based on these two issues. The scanning electron microscope micrographs, the EDS maps and X-ray diffraction analysis were also taken to indicate the solder layer thickness effects on the number of voids and their propagations in the different solder layer thicknesses. The experimental tests validate the expected results in the extracted simulations. [ABSTRACT FROM AUTHOR]

As integrated circuit (IC) industry advances to the nanometer scale, layout pattern plays more and more important role on chip fabrication. Layout-dependent effect (LDE) studies how different patterns influence the fabrication results. Chemical–mechanical polishing (CMP), one of the most important processes during IC fabrication, is strongly influenced by LDE. The purpose of this article is to show a convolutional neural network (CNN)-based method to model post-CMP surface topography problem. The method accurately predicts the topological height of the chip surface after CMP by using CNN to abstract features from layout patterns, aiming to analyze defects that may cause failure. This article first addresses about the principles and practicability of using the CNN method to build a CMP model, then builds up a complete CNN structure, and compares the CNN-based model with a traditional pressure-distribution-based CMP model. We designed test chips containing different structures and fabricated them with 28- and 45-nm process nodes. Surface topography is measured using atomic force profiler (AFP) and scanning electron microscope (SEM). The result shows that the total root-mean-squared error (RMSE) of the CNN-based model is 22.41 A, whereas the RMSE of the pressure-distribution-based model is 65.54 A. The CNN-based CMP model shows better accuracy. [ABSTRACT FROM AUTHOR]