Device Failure Mechanisms Research Articles

A Bistable Variable Infrared Emissivity Device Based on Reversible Silver Electrodeposition

AbstractReversible silver electrodeposition (RSE) can dynamically modulate visible light and infrared radiation through the reversible electrodeposition and dissolution of silver layer. However, the RSE device with bistability better than 2 h has not been reported, because the deposited silver layer may dissolve automatically without driving voltage. Here, a variable infrared emissivity device based on RSE with 24 h excellent bistability is demonstrated. A silver layer fixed at the counter electrode is used as the charge mediator, which reforms the electrochemical reactions of the counter electrode and is the key for obtaining bistability. Effects of electrolyte composition and driving voltage on the bistability are studied, and the driving voltage affects the bistability of RSE devices. This RSE device can be enlarged to 5 × 5 cm2 with uniform emissivity change of 0.48 in 2.5–25 µm using silicon wafer as the infrared transparent working electrode substrate, and display discontinuous thermal patterns through incorporating a dielectric pattern layer. The cyclability and device failure mechanism is analyzed. With the excellent bistability, the proposed RSE devices provide great application prospects in the fields of dynamic infrared information display, adaptive infrared camouflage, and smart thermal management.

Asymmetric non-slipping adhesion behavior of layered piezoelectric structures

Layered piezoelectric structures have found wide applications in micro-electro-mechanical systems (MEMS) due to their intrinsic electro-mechanical coupling effect. The adhesion effect resulting from various surface forces (e.g., the electrostatic force, capillary force, and Van der Waals force) has become one dominant factor in determining the reliability and service life of the MEMS devices. In this study, the asymmetric non-slipping adhesion behavior of layered piezoelectric structures under the action of different external loadings is investigated. A system of coupled singular integral equations are obtained for the stated problem in the framework of the generalized JKR theory, where the coupling effect between the normal and tangential contact stresses is taken into consideration. The closed-form analytical solutions of the electric displacement and stress fields within the contact zone are derived. The relations between the contact size and applied loadings are set up with the Griffith energy balance criterion. The effect of the mechanical and electric loads and the mismatch strain on the adhesion behavior of layered piezoelectric structures is discussed in detail. It is found that applying the electric load can only strengthen the adhesion effect for different types of layered piezoelectric structures. Both the inclined angle of the mechanical force and the geometric parameter of the contacting objects have significant effects on the adhesion behavior. The results obtained from present paper should be very useful for understanding the adhesion failure mechanism of the MEMS devices composed of layered piezoelectric structures.

Comprehensive,in operando, and correlative investigation of defects and their impact on device performance

Abstract Despite the long history of research that has focused on the role of defects on device performance, the studies have not always been fruitful. A major reason is because these defect studies have typically been conducted in a parallel mode wherein the semiconductor wafer was divided into multiple pieces for separate optical and structural characterization, as well as device fabrication and evaluation. The major limitation of this approach was that either the defect being investigated by structural characterization techniques was not the same defect that was affecting the device performance or else the defect was not characterized under normal device operating conditions. In this review, we describe a more comprehensive approach to defect study, namely a series mode, using an array of spatially-resolved optical, electrical, and structural characterization techniques, all at the individual defect level but applied sequentially on a fabricated device. This novel sequential approach enables definitive answers to key questions, such as: (i) how do individual defects affect device performance? (ii) how does the impact depend on the device operation conditions? (iii) how does the impact vary from one defect to another? Implementation of this different approach is illustrated by the study of individual threading dislocation defects in GaAs solar cells. Additionally, we briefly describe a 3-D Raman thermometry method that can also be used for investigating the roles of defects in high power devices and device failure mechanisms.

Thermal fatigue reliability improvement of leadless ceramic chip carrier solder joints

In order to improve the thermal fatigue reliability of LCCC (Leadless Ceramic Chip Carrier) solder joints, the assembly process and failure mechanism of LCCC devices are analyzed. It is concluded that the solder joints height is the main factor to improve its thermal fatigue reliability. Reliability qualification tests are performed to contrast the improvement effect of several methods. The Sn10Pb90 column mounting specimen can greatly improve the fatigue reliability and can adapt to most environmental requirements. Some significant conclusions are drawn by comparing the tests results of different specimens. The method can also be used for the other package types to improve the reliability.

Electro-Thermally Actuated Non-Volatile Mechanical Memory With CMOS-Level Operation Voltage and Low Contact Resistance

A non-volatile mechanical memory device with CMOS-level operation voltage and low contact resistance is proposed utilizing electro-thermal actuation method for the first time. Unlike the most widely used electrostatic actuation method in microelectromechanical systems (MEMS) devices, electro-thermal actuation is known to produce large actuation force and displacement with low operation voltage, which are preferable attributes of a mechanical memory. In addition, stiction, one of the most notable failure mechanisms of MEMS devices referring to the inadvertent permanent adhesion between two surfaces, can be exploited to significantly improve the energy efficiency of mechanical memory by retaining the ON-state without power. We devised a non-volatile mechanical memory device capable of performing multiple cycles of write and erase operations with CMOS-level voltage by utilizing electro-thermal actuation and stiction. The fabricated electro-thermally actuated mechanical memory successfully performed 200 repeated cycles of write and erase operations at 0.9V and 1.0V, respectively. Thanks to the high contact force generated by electro-thermal actuation, the fabricated device achieved the contact resistance of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$17 \boldsymbol {\Omega }$ </tex-math></inline-formula> . Lastly, we confirmed that the fabricated device successfully retained both ON and OFF states upon removal of power beyond 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sup> seconds. [2021-0178]

A new technique to check the correct mounting of the power module heatsinks

Temperature management is a non-secondary aspect in the design of power circuits and systems. As a matter of facts, changes in the junction temperature have significant effects on the semiconductor device behavior; furthermore, a high junction temperature accelerates the failure mechanisms of power devices used in the power module and reduces their lifetime. Therefore, it is often necessary to introduce a suitable heat dissipation system able to keep the junction temperature within the device operating limits. Passive heatsinks represent the most widely used strategy. However, an incorrect mounting of the heatsink may cause an unacceptable junction temperature increase in a power module. Even though the heatsink was initially properly assembled, it may be affected by defects during its working lifetime. Thus, it is necessary to devise effective strategies for testing the heatsink mounting at the end of the printed circuit board production and during the operational phase. In this paper, a method to test the heatsink mounting on power module is discussed. The proposed solution does not require thermal measurements, but only electrical ones and can be performed both at the end of the power module production, by means of an automatic test equipment, and in mission using a dedicated test circuit included in the system. The method was experimentally assessed on a DC-DC buck converter, validating the proposed solution.

Effect of thermo-mechanical ageing on materials and interface properties in flexible microelectronic devices

The effect of thermal ageing, fatigue and thermo-mechanical ageing on flexible microelectronic devices is studied and reported from a materials and functional durability perspective. The degradation mechanisms of encapsulant and substrate were both studied. Property changes in encapsulant and substrate materials are analyzed and their relationships in the failure mechanisms of the flexible devices determined. Stiffening of the resin under thermal ageing conditions is associated with delamination in test vehicles, which leads to a loss of functional electrical properties. Degradation was due to the prominence of crosslinking reactions occurring during thermal oxidation at 120 °C. A moderate stiffening of the resin occurs after fatigue stress testing. Whereas this latter stiffening is similarly associated with crosslinking reactions, here, stiffening could not be induced by thermal degradation of the resin, because the stress frequency employed was low. Instead thermo-mechanical coupling occurred in two stages. Under mild conditions, the degradation mechanisms correspond to the combined effect of thermal ageing and fatigue processes. Under harsher thermo-mechanical conditions, the chain-scission mechanisms become more efficient and induce a softening of the resin.

Electrolyte-Dependent Modification of Resistive Switching in Anodic Hafnia.

Anodic HfO2 memristors grown in phosphate, borate, or citrate electrolytes and formed on sputtered Hf with Pt top electrodes are characterized at fundamental and device levels. The incorporation of electrolyte species deep into anodic memristors concomitant with HfO2 crystalline structure conservation is demonstrated by elemental analysis and atomic scale imaging. Upon electroforming, retention and endurance tests are performed on memristors. The use of borate results in the weakest memristive performance while the citrate demonstrates clear superior memristive properties with multilevel switching capabilities and high read/write cycling in the range of 106. Low temperature heating applied to memristors shows a direct influence on their behavior mainly due to surface release of water. Citrate-based memristors show remarkable properties independent on device operation temperatures up to 100 °C. The switching dynamic of anodic HfO2 memristors is discussed by analyzing high resolution transmission electron microscope images. Full and partial conductive filaments are visualized, and apart from their modeling, a concurrency of filaments is additionally observed. This is responsible for the multilevel switching mechanism in HfO2 and is related to device failure mechanisms.

Mechanical characterization and properties of continuous wave laser irradiated Ge2Sb2Te5 stripes

Crystalline micrometer size stripes in 2.2 μm thick Ge2Sb2Te5 phase-change material films were produced by irradiation with a Continuous Wave Laser of 405 nm wavelength. The shape and the dimensions of the crystallized regions were investigated by Transmission Electron Microscopy and then compared with simulations based on temperature-crystal growth velocity literature data. The temperature-time profile was determined taking into account the laser power, the optical and thermal properties of both the amorphous and crystalline phase. The mechanical properties of the amorphous and of the crystallized regions were characterized by an ultra nano-indentation technique. This procedure allows a direct and local measurement of hardness and Young's modulus in the amorphous and in the contiguous crystalline regions on the micrometer scale. The following values for Young's modulus and for hardness were obtained: 33±4 GPa and 2.00±0.3 GPa for the amorphous phase, and 51±8 GPa and 2.90±0.45 GPa for the crystalline phase. The stresses induced by the density increase in the crystallized region cause, on the irradiated surface, a series of fracture whose characteristic behavior depends on the laser power and on the spacing between two contiguous scans. These results are of relevance for the mechanical failure mechanisms in potential phase-change devices.

Enhance Reliability of Semiconductor Devices in Power Converters

As one of the most vulnerable components to temperature and temperature cycling conditions in power electronics converter systems in these application fields as wind power, electric vehicles, drive system, etc., power semiconductor devices draw great concern in terms of reliability. Owing to the wide utilization of power semiconductor devices in various power applications, especially insulated gate bipolar transistors (IGBTs), power semiconductor devices have been studied extensively regarding increasing reliability methods. This study comparatively reviews recent advances in the area of reliability research for power semiconductor devices, including condition monitoring (CM), active thermal control (ATC), and remaining useful lifetime (RUL) estimation techniques. Different from previous review studies, this technical review is carried out with the aim of providing a comprehensive overview of the correlation between various enhancing reliability techniques and discussing the corresponding merits and demerits by using 144 related up-to-date papers. The structure and failure mechanism of power semiconductor devices are first investigated. Different failure indicators and recent associated CM techniques are then compared. The ATC approaches following the type of converter systems are further summarized. Furthermore, RUL estimation techniques are surveyed. This paper concludes with summarized challenges for future research opportunities regarding reliability improvement.

Water diffusivity transition in fumed silica-filled polydimethylsiloxane composite: Correlation with the interfacial free volumes characterized by positron annihilation lifetime spectroscopy

Fumed silica (FS)-filled polydimethylsiloxane (PDMS) composite is widely used as the external insulating material in power grid. The function of PDMS composite is to keep the core of an insulation device being dry by preventing the permeation of outside water. To study water diffusion in PDMS composite helps to shed light upon the failure mechanism of the insulation devices. In this paper, positron annihilation lifetime spectroscopy (PALS) and electrochemical impedance spectroscopy (EIS) were applied to study the FS/PDMS interface structure and water diffusion in PDMS composite. It is found that the FS has two basic existing states in PDMS matrix: dispersed state and percolated state, and the percolation threshold of FS is fitted to be 6.0 wt.%. In the dispersed state, the FS particles are randomly dispersed in PDMS matrix. The values of $$\tau _3$$ remain stable, being approximately 1.0 ns, indicating no overlaps of the FS/PDMS interfaces. Moreover, water cannot diffuse through the sample after corona aging. In the percolated state, the FS particles are tightly packed in the PDMS matrix. The values of $$\tau _3$$ decrease with the weight fraction of FS, suggesting the overlapping of the FS/PDMS interfaces. As the FS percolates in sample bulk, these overlapped FS/PDMS interfaces provide continuous diffusion tunnels for water, thus resulting in failure of the composite after corona aging. It is found that polarization and discharge of the electrons at FS/PDMS interface under corona discharge is the main mechanism that leads to the failure of the composite bulk.

Remaining Useful Lifetime estimation for Electronic Power modules using an analytical degradation model

Power electronic modules undergo electro-thermal stresses due to power losses that lead to several kinds of degradations, and finally to failure. In order to prevent power electronic module failure, one should assess its state of health in real-time operation. For this purpose, Prognostics and Health Management (PHM) approach could be a promising tool for reliability evaluation for an IGBT device. The Insulated Gate Bipolar Transistor is a three-terminal power semiconductor device used as an electronic switch which combines high efficiency and fast switching. In this paper, an analytical model is proposed that describes the metallization to wire-bond contact resistance. This model computes the crack length and then using online measurement the rate of crack propagation is computed and used to predict the future crack lengths with the assumption of linearity in crack propagation. The main failure mechanism of the IGBT device in this paper is the crack propagation in the wire-bond interconnection. The usual aging indicator of such damages is the voltage between the collector and the emitter of current (VCE) that increases with degradation. The analytical model is related to this indicator and it is based on the contact resistance theory and constriction current lines. The proposed model is hence used to build a prognostics model for estimating the remaining useful lifetime (RUL) of IGBT power modules. The prognostics model is illustrated using aging data coming from accelerated power cycling tests with different stress conditions. The first cycling test is under the conditions of stress duration ton = 3sec and junction temperature swing amplitudes ΔTj = 110 ºC and the second cycling test is under ton = 3sec and ΔTj = 90ºC. Results show a prognostics capability.

Intravascular Ultrasound-guided Versus Angiography-guided Percutaneous Coronary Intervention: Evidence from Observational Studies and Randomized Controlled Trials

Coronary angiography has been considered the gold standard for the diagnosis of coronary artery disease and guidance of percutaneous coronary intervention (PCI). However, 2D-projection angiography cannot completely reflect the 3D coronary lumen. Intravascular ultrasound (IVUS) can overcome a number of limitations of coronary angiography by providing more information about the dimensions of the vessel lumen, plaque characteristics, stent deployment, and the mechanisms of device failure. Growing data from observational studies and randomized controlled trials have confirmed the clinical benefit of IVUS guidance during PCI. This article summarizes the evidence regarding IVUS guidance to highlight its advantages and to support the use of IVUS during PCI.

Study on structural failure mechanism of explosive separation device based on the damage constitutive model

The explosion separation device is the critical factor to ensure the effective separation of the payload and the launch vehicle. The rationality of the structural strength is usually assessed by the real explosion separation test. The separation of components in the deformation and damage is difficult to be obtained. The traditional method, based on the elasto-plastic constitutive, is also unable to simulate the damage of each component in the separation. The traditional strength check can be calculated by the elasto-plastic constitutive relation for large deformation, while the damage simulation can only be obtained by the progressive damage fracture. The metal material dynamic damage constitutive is applied based on the ABAQUES to simulate the damage and failure of the explosion separation. Then the finite element model of the explosion separation device can be established based on the elasto-plastic damage constitutive model, and the process of the ground test of the explosive separation device can be reproduced by the simulation of the corresponding FEM model. And then the weakness of the explosive separation device is finally determined by the calculation results. The experimental results are consistent with the simulation, which confirms the accuracy of the proposed method. The solution idea provides a reference basis for the product design and dynamic damage simulation.

Modelling and experiments to identify high-risk failure scenarios for testing the safety of lithium-ion cells

Intentionally inducing worst-case thermal runaway scenarios in Li-ion cells on-demand is a definitive way to test the efficacy of battery systems in safely mitigating the consequences of catastrophic failure. An internal short-circuiting (ISC) device is implanted into three 18650 cell designs: one standard, one with a bottom vent, and one with a thicker casing. Through an extensive study of 228 cells, the position at which thermal runaway initiates is shown to greatly affect the tendency of cells to rupture and incur side-wall breaches at specific locations. The risks associated with each failure mechanism and position of the ISC device are quantified using a custom calorimeter that can decouple the heat from ejected and non-ejected contents. Causes of high-risk failure mechanisms, such as bursting and side-wall breaches, are elucidated using high-speed synchrotron X-ray imaging at 2000 frames per second and image-based 3D thermal runaway computational models, which together are used to construct a comprehensive description of external risks based on internal structural and thermal phenomena.

Temperature and thermal stress around an elliptic functional defect in a thermoelectric material

Functional defect leads to high temperature as well as considerable thermal stress in thermoelectric materials, which is one of the major reliability failure mechanisms of thermoelectric devices. In this perspective, the thermal-electric-elastic fields around an elliptic functional defect in a two-dimension thermoelectric plate is analyzed based on the complex variable method, and the field distributions have been obtained in closed-form. The results show that the temperature at the defect tip increases with the defect size, and can surpass the temperature at the hot end and even exceed the material melt point. Besides, both the von Mises stresses within the matrix and defect can exceed the yield stresses of many materials. These results can be used for the fracture study and reliability analysis of thermoelectric materials.

Analysis of Forward Surge Performance of SiC Schottky Diodes

Silicon Carbide JBS diodes are capable, in forward bias, of carrying surge current of magnitude significantly higher than their rated current, for short periods. In this work, we examine the mechanisms of device failure due to excess surge current by analyzing variation of failure current with device current and voltage ratings, as well as duration of current surge. Physical failure analysis is carried out to correlate to electrical failure signature. We also quantify the impact, on surge current capability, of the resistance of the anode ohmic contact to the p-shielding region.

Peri‐prosthetic tissue reaction to discontinuation of negative pressure wound therapy around porous titanium percutaneous devices

Negative pressure wound therapy (NPWT) has been reported to limit epithelial downgrowth, one of the failure mechanisms of percutaneous devices. In a previous study, when NPWT was applied for 4 weeks (NPWT Group) to porous coated titanium percutaneous devices, downgrowth (5 ± 4%; mean ± one SD) was significantly reduced compared to untreated controls (Untreated Group) (16 ± 6%; p ≤ 0.01). However, it was unclear whether this beneficial effect was sustained when NPWT was discontinued. In order to test this, porous coated titanium percutaneous devices were implanted into 6 hairless guinea pigs. Post-surgery, animals received 4 weeks of NPWT treatment followed by 4 weeks of no treatment (Discontinued Group). At necropsy, the devices and surrounding tissues were harvested and processed. Quantitative downgrowth measurements and qualitative analyses of tissue characteristics were performed, and compared to historical controls (NPWT and Untreated Groups). The Discontinued Group, at 8 weeks, had significantly more downgrowth than the NPWT Group at 4 weeks (23 ± 3% vs. 5 ± 4%; p ≤ 0.01). At 8 weeks, the Discontinued Group qualitatively appeared to exhibit reduced numbers of blood vessels and increased degree of fibrosis compared to the NPWT Group at 4 weeks. This study suggests that NPWT will only be an effective treatment for limiting downgrowth if used continuously. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2018. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 564-572, 2019.

Lifetime of Organic Salt Photovoltaics

AbstractSolar energy deployment can be augmented with the use of wavelength‐selective transparent photovoltaics (PVs). Moving forward, operating lifetime is arguably among the most important challenge that must be addressed to increase commercial viability of these emerging technologies. In this work, the lifetimes of PVs with organic near‐infrared selective small molecules and molecular salts are investigated. This is the first comprehensive lifetime study on devices featuring organic salts with varied counterions. Based on the tunability afforded by anion exchange, an extrapolated lifetime of 7 ± 2 years from continuous illumination measurements on organic salt devices held at the maximum power point is demonstrated. These lifetimes are compared with changes in external quantum efficiency, hydrophobicity, molecular orbital levels, and optical absorption to determine the limiting characteristics and failure mechanisms of PV devices utilizing each donor. A key correlation between the lifetime and the hydrophobicity of the donor layer is uncovered. This could provide a targeted parameter for designing organic molecules and salts with exceptional lifetime and enhanced commercial viability.

Assessing failure in epitaxially encapsulated micro-scale sensors using micro and nano x-ray computed tomography

Abstract