Intrinsic Failure Research Articles

Design a degradation condition monitoring system scheme for rolling bearing using EMD and PCA

PurposeRolling bearings based on rotating machinery are one of the most widely used in industrial applications because of their low cost, high performance and robustness. The purpose of this paper is to describe how to identify degradation condition of rolling bearing and predict its fault time in big data environment in order to achieve zero downtime performance and preventive maintenance for the rolling bearing.Design/methodology/approachThe degradation characteristic parameters of rolling bearings including intrinsic mode energy and failure frequency were, respectively, extracted from the pre-processed original vibration signals using EMD and Hilbert transform. Then, Spearman’s rank correlation coefficient and PCA were used to obtain the health index of the rolling bearing so as to detect the appearance of degradations. Furthermore, the degradation condition of the rolling bearings might be identified through implementing the monotonicity analysis, robustness analysis and degradation analysis of the health index.FindingsThe effectiveness of the proposed method is verified by a case study. The result shows that the proposed method can be applied to monitor the degradation condition of the rolling bearings in industrial application.Research limitations/implicationsFurther experiment remains to be done so as to validate the effectiveness of the proposed method using Apache Hadoop when massive sensor data are available.Practical implicationsThe paper proposes a methodology for rolling bearing condition monitoring representing the steps that need to be followed. Real-time sensor data are utilized to find the degradation characteristics.Originality/valueThe result of the work presented in this paper form the basis for the software development and implementation of condition monitoring system for rolling bearings based on Hadoop.

Urinary Calprotectin Differentiates Between Prerenal and Intrinsic Acute Renal Allograft Failure

Urinary calprotectin has recently been identified as a promising biomarker for the differentiation between prerenal and intrinsic acute kidney injury (AKI) in the nontransplant population. The present study investigates whether calprotectin is able to differentiate between these 2 entities in transplant recipients as well. Urinary calprotectin was assessed by enzyme-linked immunosorbent assay in 328 subjects including 125 cases of intrinsic acute allograft failure, 27 prerenal graft failures, 118 patients with stable graft function, and 58 healthy controls. Acute graft failure was defined as AKI stages 1 to 3 (Acute Kidney Injury Network criteria), exclusion criteria were obstructive uropathy, urothelial carcinoma, and metastatic cancer. The clinical differentiation of prerenal and intrinsic graft failure was performed either by biopsy or by a clinical algorithm including response to fluid repletion, history, physical examination, and urine dipstick examination. Reasons for intrinsic graft failure comprised rejection, acute tubular necrosis, urinary tract infection/pyelonephritis, viral nephritis, and interstitial nephritis. Calprotectin concentrations of patients with stable graft function (50.4 ng/mL) were comparable to healthy controls (54.8 ng/mL, P = 0.70) and prerenal graft failure (53.8 ng/mL, P = 0.62). Median urinary calprotectin was 36 times higher in intrinsic AKI (1955 ng/mL) than in prerenal AKI (P < 0.001). Receiver-operating characteristic curve analysis revealed a high accuracy of calprotectin (area under the curve, 0.94) in the differentiation of intrinsic versus prerenal AKI. A cutoff level of 134.5 ng/mL provided a sensitivity of 90.4% and a specificity of 74.1%. Immunohistochemical stainings for calprotectin in renal allograft biopsy specimens confirmed the serological results. Urinary calprotectin is a promising biomarker for the differentiation of prerenal and intrinsic acute renal allograft failure.

Skeletal Muscle and Lymphocyte Mitochondrial Dysfunctions in Septic Shock Trigger ICU-Acquired Weakness and Sepsis-Induced Immunoparalysis.

Fundamental events driving the pathological processes of septic shock-induced multiorgan failure (MOF) at the cellular and subcellular levels remain debated. Emerging data implicate mitochondrial dysfunction as a critical factor in the pathogenesis of sepsis-associated MOF. If macrocirculatory and microcirculatory dysfunctions undoubtedly participate in organ dysfunction at the early stage of septic shock, an intrinsic bioenergetic failure, sometimes called “cytopathic hypoxia,” perpetuates cellular dysfunction. Short-term failure of vital organs immediately threatens patient survival but long-term recovery is also severely hindered by persistent dysfunction of organs traditionally described as nonvital, such as skeletal muscle and peripheral blood mononuclear cells (PBMCs). In this review, we will stress how and why a persistent mitochondrial dysfunction in skeletal muscles and PBMC could impair survival in patients who overcome the first acute phase of their septic episode. First, muscle wasting protracts weaning from mechanical ventilation, increases the risk of mechanical ventilator-associated pneumonia, and creates a state of ICU-acquired muscle weakness, compelling the patient to bed. Second, failure of the immune system (“immunoparalysis”) translates into its inability to clear infectious foci and predisposes the patient to recurrent nosocomial infections. We will finally emphasize how mitochondrial-targeted therapies could represent a realistic strategy to promote long-term recovery after sepsis.

A Trinitarian Response to Buddhist Antitheistic Arguments

A Trinitarian Response to Buddhist Antitheistic Arguments John B. King Jr. In his battle against theism, Vasubandhu developed three classical arguments that have set the agenda for Buddhist apologetics.1 More recently, Mattieu Ricard has employed these arguments within the field of religion and science.2 Because these arguments make their case from distinct angles of attack, they function as distinct means to a common end. Yet it is precisely this end that is problematic. Because the arguments rebut a bare monotheism, they fail to address the complexity of Trinitarian theism.3 As a result, the Buddhist arguments appear to be strawperson arguments from the Trinitarian side. This failure to establish a point of contact is not an intrinsic failure of Buddhist polemics. Rather it is the result of two historical accidents. First, the Buddhist arguments were originally developed in a non-Christian context where Trinitarian theism was not in play. Second, Christians have often advanced a bare monotheism in their apologetic work because they have failed to grasp the architectonic significance of the Trinity.4 For both of these reasons, Buddhist antitheistic arguments are underdeveloped. Consequently, I cannot claim to refute the Buddhist case against theism by responding to these arguments. Indeed, I would commit the strawperson fallacy myself if I were to do so. Instead, I will here restrict myself to the more limited claim that Buddhist antitheistic arguments need to be updated in light of Trinitarian theism. To make this case, my argument will unfold in three steps. First, to provide a basis for the subsequent discussion, I will present the significant features of my apologetic method. Second, I will then respond to the first of three classical arguments by Vasubandhu. Finally, I will examine the more recent arguments by Matthieu Ricard. Because Ricard treats Vasubandhu's second argument in a more concise way, I will respond to Ricard's version of the argument rather than Vasubandhu's. I will pass over Vasubandhu's third argument without comment since it has reference to multiple creators and is therefore irrelevant to a Buddhist engagement with Christianity. Before proceeding with this discussion, however, I must say a few words about the role of apologetics in an interreligious context. Although some may fear that apologetics is detrimental to interreligious dialogue, the reverse is actually the case. Because my approach leaves space for a Buddhist response, it is simultaneously dialogical and apologetic. Moreover, my approach is warranted by Francis Clooney's [End Page 157] framework for comparative theology. In his book Hindu God, Christian God, Clooney says that comparative theology has four dimensions of increasing intensity and specificity that drive the interreligious conversation forward. In order of increasing depth, these dimensions are (1) the interreligious dimension, (2) the comparative dimension, (3) the dialogical dimension, and (4) the confessional/apologetic dimension.5 In pursuing a dialogical apologetics, therefore, I am seeking a deep interreligious engagement. apologetic method In an apologetic encounter, Christianity and Buddhism confront each other thoroughly and systematically.6 Such exhaustive confrontation follows from the fact that Christianity and Buddhism are all-encompassing worldviews, neither of which recognizes a higher standard for adjudicating their differences. To the contrary, because these views are all-encompassing, they constitute competing circularities in which the starting point, the method, and the conclusions of each system are intimately involved in one another. Thus, the argument between them must proceed by way of internal critique and must therefore be indirect rather than direct. Stated differently, Buddhist and Christian apologists must reason by way of presupposition, comparing the two systems as transcendental conditions for grounding knowledge. This indirect approach of reasoning by presupposition was initially laid out by Cornelius Van Til in the 1930s and eventually became known as "presuppositional apologetics." Van Til provides a lucid description of this process: The method of reasoning by presupposition may be said to be indirect rather than direct. The issue between believers and non-believers in Christian theism cannot be settled by a direct appeal to "facts" or "laws" whose nature and significance is already agreed upon by both parties to the debate. The question is rather as to what is the final reference-point required to make the "facts...

A study of acute kidney injury inhospitalized preterm neonates in NICU.

This study was carried out to determine the incidence, clinical features, etiology and outcome of functional and intrinsic acute kidney injury (AKI) in preterm neonates. This is a prospective observational study on premature infants admitted to the neonatal intensive care unit (NICU) over an eight month period. All biochemical parameters of renal function tests were monitored and statically analyzed. The study included 450 infants; of them 300 were inborn and 150 infants were outborn and transported to the NICU. Mean gestational age, weight, and age at the time of AKI diagnosis were 32.3 weeks, 1.66 kg and 3.23 days respectively. The male: female ratio was 1.84:1. Incidence of AKI was higher in low birth weight babies. Sluggishness and refusal for feed were most common symptoms. Birth asphyxia and septicemia were the most common early and late cause of AKI. Hyponatremia was the most common electrolyte disturbance. The incidences of AKI, functional renal failure, and intrinsic renal failure were 12%, 48.14%, and 51.85% respectively. AKI is not uncommon in preterm infants. The early recognition and aggressive management of episodes of shock which often precede AKI could be life-saving.

Mechanical behaviour of staggered array of mineralised collagen fibrils in protein matrix: Effects of fibril dimensions and failure energy in protein matrix

Many biological composite materials such as bone have demonstrated unique mechanical performance, i.e., a combination of superior stiffness and toughness. It has become increasingly clear that the constituents at the nano- and micro-length scales play a critical role in determining the mechanical performance of these biological composites. In this study, the underlying mechanisms governing the mechanical behaviour of the staggered array of mineralised collagen fibrils (MCF) embedded in extra-fibrillar protein matrix were numerically investigated. The evolution of damage zone in protein was estimated using cohesive zone models (CZM). The results indicate that the mechanisms and mechanical behaviour of MCF array are largely dependent on the MCF dimensions and the intrinsic failure energy in extra-fibrillar protein matrix.

The research motivation scale: validation with faculty from American schools of education

PurposeThis paper aims to compare the psychometric properties of the Research Motivation Scale (RMS) from faculty in schools of education in American research universities to previous findings on this scale when administered to science, technology, engineering and mathematics (STEM) faculty.Design/methodology/approachThis study was an exploratory, quantitative study using survey research methods, and utilizing confirmatory and exploratory factor analyses and statistical tests of population differences.FindingsResults indicate an adequate fit to a previously found three-factor structure. However, a new four-factor model, accounting for 47 per cent of the variance, was identified as a better fit: failure avoidance, intrinsic reward – satisfaction, intrinsic reward – joy and extrinsic reward. The overall reliability for the entire measure was 0.76. Intrinsic motivation and failure avoidance were rated statistically more important by education faculty than STEM faculty.Research limitations/implicationsAs an exploratory study and because of the chosen research approach, generalizations may be limited and further research in this area is recommended.Practical implicationsThis study contributes to the literature on RMS with data from education faculty. Results support conceptual frameworks regarding faculty outcomes and professional growth, and suggest ways faculty may be encouraged to increase research productivity.Social implicationsThis paper includes implications for societal support for research institutions by modeling factors that affect faculty motivations to produce research and thereby increase institutional productivity.Originality/valueThis study builds on conceptual frameworks, explores the use of the RMS with education faculty and compares faculty motivation to conduct research across disciplines.

Hyperactivated Stat3 boosts axon regeneration in the CNS

Axonal regeneration after spinal cord injury (SCI) is intrinsically and extrinsically inhibited by multiple factors. One major factor contributing to intrinsic regeneration failure is the inability of mature neurons in the central nervous system (CNS) to activate regeneration-associated transcription factors (TFs) post-injury. A prior study identified TFs overexpressed in neurons of the peripheral nervous system (PNS) compared to the CNS; some of these could be involved in the ability of PNS neurons to regenerate. Of these, signal transducer and activator of transcription 3 (STAT3), as well its downstream regeneration-associated targets, showed a significant upregulation in PNS neurons relative to CNS neurons, and a constitutively active variant of Stat3 (Stat3CA) promoted neurite growth when expressed in cerebellar neurons (Lerch et al., 2012; Smith et al., 2011). To further enhance STAT3's neurite outgrowth enhancing activity, Stat3CA was fused with a viral activation domain (VP16). VP16 hyperactivates TFs by recruiting transcriptional co-factors to the DNA binding domain (Hirai et al., 2010). Overexpression of this VP16-Stat3CA chimera in primary cortical neurons led to a significant increase of neurite outgrowth as well as Stat3 transcriptional activity in vitro. Furthermore, in vivo transduction of retinal ganglion cells (RGCs) with AAV constructs expressing VP16-Stat3CA resulted in regeneration of optic nerve axons after injury, to a greater degree than for those expressing Stat3CA alone. These findings confirm and extend the concept that overexpression of hyperactivated transcription factors identified as functioning in PNS regeneration can promote axon regeneration in the CNS.

The direct and indirect effects of nanotwin volume fraction on the strength and ductility of coarse-grained metals

Coarse-grained (CG) metals strengthened by nanotwinned (NT) regions have an excellent combination of high strength and good ductility. In this paper, numerical simulations based on the mechanism-based strain gradient plasticity and the Johnson–Cook failure criterion are carried out to investigate the direct and indirect effects of volume fraction of the NT regions and several other key attributes on the strength and ductility of the CG metal strengthened by NT regions. Our results indicate that twin spacing, shape, distribution, and volume fraction of NT regions all have significant effects, and that, as the volume fraction increases, the roles played by the twin spacing and shape of NT regions also change. At low volume fraction of NT regions, their shape is found to have a significant influence on the overall ductility. As the volume fraction increases, the shape effect on the ductility is found to diminish even though the effect on the strength is noted to continue to enhance. While twin spacing and volume fraction of NT regions have shown different effects on the ductility, the effect of twin spacing always decreases as the volume fraction increases. During the simulations we have also discovered several intrinsic deformation and failure mechanisms through the analysis of microcrack initiation sites and microcrack propagation paths. It is believed that this simulation has revealed significant insights into the roles of volume fraction, twin spacing, shape, and distribution of NT regions on the strength and ductility of this novel class of materials.

On the Viability of Conspiratorial Beliefs.

Conspiratorial ideation is the tendency of individuals to believe that events and power relations are secretly manipulated by certain clandestine groups and organisations. Many of these ostensibly explanatory conjectures are non-falsifiable, lacking in evidence or demonstrably false, yet public acceptance remains high. Efforts to convince the general public of the validity of medical and scientific findings can be hampered by such narratives, which can create the impression of doubt or disagreement in areas where the science is well established. Conversely, historical examples of exposed conspiracies do exist and it may be difficult for people to differentiate between reasonable and dubious assertions. In this work, we establish a simple mathematical model for conspiracies involving multiple actors with time, which yields failure probability for any given conspiracy. Parameters for the model are estimated from literature examples of known scandals, and the factors influencing conspiracy success and failure are explored. The model is also used to estimate the likelihood of claims from some commonly-held conspiratorial beliefs; these are namely that the moon-landings were faked, climate-change is a hoax, vaccination is dangerous and that a cure for cancer is being suppressed by vested interests. Simulations of these claims predict that intrinsic failure would be imminent even with the most generous estimates for the secret-keeping ability of active participants—the results of this model suggest that large conspiracies (≥1000 agents) quickly become untenable and prone to failure. The theory presented here might be useful in counteracting the potentially deleterious consequences of bogus and anti-science narratives, and examining the hypothetical conditions under which sustainable conspiracy might be possible.

Intrinsic strength and failure behaviors of ultra-small single-walled carbon nanotubes

The intrinsic mechanical strength of single-walled carbon nanotubes (SWNTs) within the diameter range of 0.3–0.8nm has been studied based on ab initio density functional theory calculations. In contrast to predicting “smaller is stronger and more elastic” in nanomaterials, the strength of the SWNTs is significantly reduced when decreasing the tube diameter. The results obtained show that the Young’s modulus E significantly reduced in the ultra-small SWNTs with the diameter less than 0.4nm originates from their very large curvature effect, while it is a constant of about 1.0TPa, and independent of the diameter and chiral index for the large tube. We find that the Poisson’s ratio, ideal strength and ideal strain are dependent on the diameter and chiral index. Furthermore, the relations between E and ideal strength indicate that Griffith’s estimate of brittle fracture could break down in the smallest (2, 2) nanotube, with the breaking strength of 15% of E. Our results provide important insights into intrinsic mechanical behavior of ultra-small SWNTs under their curvature effect.

Renal failure index and assessment of renal function in asphyxiated newborns

Objective: To assess the renal failure index (RFI) in asphyxiated neonates in relation to other clinical and laboratory findings among those with acute renal failure, whether prerenal or intrinsic renal failure. Background: Asphyxia is an important cause of morbidity and mortality among neonates. It leads to multiorgan dysfunction and redistribution of cardiac output to maintain cerebral, cardiac and adrenal perfusion while potentially compromising renal, gastrointestinal and skin perfusion. Thus, acute renal failure is recognized as a complication of birth asphyxia. Materials and Methods: This case–control study included 80 neonates divided into two groups: the patient group (40 babies with perinatal asphyxia) and the control group (40 normal babies). In all patients, hypoxic ischemic encephalopathy staging (Sarnat and Sarnat) was performed. Blood and urinary parameters for renal function were assessed in all newborns, and fractional excretion of sodium (FENa) and the RFI were also calculated. The results obtained were analyzed and compared within subgroups using the computer program statistical package for social science, version 16. Results: Acute renal failure was noted in 19 patients in the patient group (47.5%): 16 of them (40%) had prerenal failure and three had intrinsic renal failure (7.5%). FENa and the RFI were found to be the most useful in evaluating babies with renal failure, as these derived renal indices were more reliable than individual parameters. FENa and RFI increased with increasing hypoxic ischemic encephalopathy staging. Conclusion: Perinatal asphyxia is an important cause of neonatal acute renal failure, which is predominantly prerenal failure. FENa and RFI are useful parameters for assessing the renal function in these neonates and can be used to differentiate prerenal failure from intrinsic renal failure, and thus helps in proper management.

Outcomes After Cochlear Implantation in the Very Elderly.

To evaluate the outcomes after cochlear implantation (CI) in the elderly population, with a particular emphasis on perioperative complications, dizziness, and speech perception outcomes. A retrospective cohort study of elderly cochlear implant patients. Tertiary referral center (Cochlear Implant Clinic, Royal Victorian Eye and Ear Hospital, Melbourne). All patients aged 75 and above at the time of first cochlear implant (N = 150). Comparison was made between groups aged 85+ to 80-84, and 75-79. All patients received Nucleus devices (either CI512 or CI24RE(CA)). Speech recognition scores both pre- and postimplantation, symptomatic dizziness and effects upon independent living after surgery, and the incidence of perioperative medical and surgical complications. Complications were classified as major (intrinsic device failure, device migration, extracochlear insertion, meningitis, surgical site infection requiring reoperation, wound breakdown, permanent facial nerve paralysis) and minor (tinnitus, transient facial nerve palsy, facial nerve stimulation, taste disturbance, delayed wound healing). All three cohorts had poor preoperative speech perception. There was significant improvement in postoperative word scores at 3 and 12 months across all groups. There was no statistically significant difference between the three cohorts in terms of speech recognition outcomes at 3 and 12 months. After surgery, more than 20% of patients at all ages experienced transient imbalance, although the incidence did not differ significantly between age groups (p = 0.71). In total, there were 13 major complications in 7 patients (4.7%), and 28 minor complications in 25 patients (16.7%). Postoperative disequilibrium was commonly observed in this elderly population, yet patients still benefited with improved speech perception after cochlear implantation. Elderly patients can benefit from cochlear implantation, and age should not be a limitation for CI surgery. Cochlear implantation can be done safely and provides significant patient benefits.

A model for analysis of wellbore stability considering the effects of weak bedding planes

In conventional analysis of wellbore stability, rock is usually assumed to be isotropic, but errors occur when isotropic theory is used if there are weak bedding planes that represent the properties of rock anisotropy. Therefore, in this paper, based on circumferential stresses and a new analysis of geometrical relationships of weak bedding planes and wellbore, a new wellbore stability model that considers the effects of weak bedding planes is introduced; then, a comparison is made by comparing the new model with the intrinsic rock failure model based on actual field data, which reveals that wellbore is less stable when weak bedding planes are considered, that the wellbore of cross-dip wells is less stable than that of up-dip wells and down-dip wells in the strike-slip stress regime and that wellbore quality is better in up-dip wells. Furthermore, results show that dip angles and dip directions of weak bedding planes have significant effects on wellbore stability for different inclination angles and wellbore azimuths. Regarding the effects of in-situ stress regimes, it is found that the wellbore of down-dip wells is overall more stable and that the maximum equivalent collapse density (MECD) of wells drilled along the wellbore azimuth θIA = 270–300° is relatively smaller in the normal fault stress regime; also, in the reverse fault stress regime, the MECD of both up-dip wells and wells drilled along θIA = 90–150° is relatively small. Finally, the influence of the anisotropic coefficient of horizontal stresses is also analyzed.

Analyzing complications of minimally invasive pediatric cochlear implantation: A review of 248 implantations

PurposeThis study aims to report the postoperative complications and management of cochlear implantation in pediatric patients at our institution. All procedures were carried out by a single surgeon utilizing minimally invasive techniques. The impact of past surgical history of tympanostomy tubes was also reviewed to access association with postoperative complications. Materials and methodsAll children receiving cochlear implants at our institution between April 2003 and October 2014 were reviewed. Complications were grouped into “major” and “minor” depending on degree of management and “immediate,” “early,” and “delayed” depending on time of presentation. ResultsIn our series, 248 cochlear implants were placed into 141 children. The mean age at time of surgery was 4.8years. The overall complication rate per ear was 16.5%, 5.2% being major and 11.3% being minor complications. Complications arose in the first 30days following surgery in 8.4% of patients, with acute otitis media being the most common. A history of tympanostomy tubes did not impact complication rate. Excluding device failures, major complication rate was 2.4%. Hematoma was not encountered, and delayed seroma occurred in one patient. ConclusionMinimally invasive cochlear implantation carries a low complication rate. The most common major complication was intrinsic device failure, and the most common minor complication was acute otitis media. Past medical history of chronic otitis media with tympanostomy tube placement prior to cochlear implantation did not have a statistically significant impact on postoperative complication rates. Given the rarity of hematomas and seromas, pressure dressings appear to be unnecessary with this approach.

The Registry of the International Society for Heart and Lung Transplantation: Eighteenth Official Pediatric Heart Transplantation Report—2015; Focus Theme: Early Graft Failure

The Registry of the International Society for Heart and Lung Transplantation: Eighteenth Official Pediatric Heart Transplantation Report—2015; Focus Theme: Early Graft Failure

Intrinsic fault tolerance of multilevel Monte Carlo methods

Monte Carlo (MC) and multilevel Monte Carlo (MLMC) methods applied to solvers for Partial Differential Equations with random input data are proved to exhibit intrinsic failure resilience. Sufficient conditions are provided for non-recoverable loss of a random fraction of MC samples not to fatally damage the asymptotic accuracy versus work of a MC simulation. Specifically, the convergence behavior of MLMC methods on massively parallel hardware with runtime faults is analyzed mathematically and investigated computationally. Our mathematical model assumes node failures which occur uncorrelated of MC sampling and with general sample failure statistics on the different levels and which also assume absence of checkpointing, i.e., we assume irrecoverable sample failures with complete loss of data. Modifications of the MLMC with enhanced resilience are proposed. The theoretical results are obtained under general statistical models of CPU failure at runtime. Particular attention is paid to node failures with so-called Weibull failure models on massively parallel stochastic finite volume computational fluid dynamics simulations are discussed. We discuss the resilience of massively parallel stochastic Finite Volume computational fluid dynamics simulations.

Metallization Reliability and Defectivity in Compound Semiconductors

Compound semiconductor devices are in mass volume production yet our understanding of reliability and defectivity of III-V materials is still evolving. Process-induced defects in electroplated Au interconnect metallization on GaAs devices were detected during the course of reliability testing. Abnormally high lognormal sigmas (σ > 0.7) indicated the existence of a bi-modal failure mechanism. A distinct early lifetime failure mode was observed along with the intrinsic electromigration metallization wear-out failure mode. Increased temperature stress showed only a slight acceleration on the early failure mechanism but selection of a higher resistance degradation failure percentage criterion reduced the extent of these early failures. Physical characterization of the electroplated Au film revealed as-deposited nanoscale voids. Elimination of these voids through process improvement as well as suggested mechanisms for the early failures is discussed.

Metallization Reliability and Defectivity in Compound Semiconductors

Compound semiconductor devices are in mass volume production, yet our understanding of reliability and defectivity of III-V materials is still evolving. Process-induced defects in electroplated Au interconnect metallization on GaAs devices were detected during the course of reliability testing. Abnormally high lognormal sigmas (σ > 0.7) indicated the existence of a bi-modal failure mechanism. A distinct early lifetime failure mode was observed along with the intrinsic electromigration metallization wear-out failure mode. Failure analysis of an early Au structure failure showed an unusually large void at the atypical anode end. Physical characterization of the electroplated Au film revealed as-deposited nanoscale voids. Elimination of these voids through process improvement as well as proposed mechanisms for the early Au failures are discussed.

Probing the intrinsic failure mechanism of fluorinated amorphous carbon film based on the first-principles calculations.

Fluorinated amorphous carbon films exhibit superlow friction under vacuum, but are prone to catastrophic failure. Thus far, the intrinsic failure mechanism remains unclear. A prevailing view is that the failure of amorphous carbon film results from the plastic deformation of substrates or strong adhesion between two contacted surfaces. In this paper, using first-principles and molecular dynamics methodology, combining with compressive stress-strain relation, we firstly demonstrate that the plastic deformation induces graphitization resulting in strong adhesion between two contacted surfaces under vacuum, which directly corresponds to the cause of the failure of the films. In addition, sliding contact experiments are conducted to study tribological properties of iron and fluorinated amorphous carbon surfaces under vacuum. The results show that the failure of the film is directly attributed to strong adhesion resulting from high degree of graphitization of the film, which are consistent with the calculated results.