Physical Failure Analysis Research Articles

Laboratory High-Contrast X-ray Microscopy of Copper Nanostructures Enabled by a Liquid-Metal-Jet X-ray Source.

High-resolution imaging of Cu/low-k on-chip interconnect stacks in advanced microelectronic products is demonstrated using full-field transmission X-ray microscopy (TXM). The comparison of two lens-based laboratory X-ray microscopes that are operated at two different photon energies, 8.0 keV and 9.2 keV, shows a contrast enhancement for imaging of copper nanostructures embedded in insulating organosilicate glass of a factor of 5 if 9.2 keV photons are used. Photons with this energy (Ga-Kα radiation) are generated from a Ga-containing target of a laboratory X-ray source applying the liquid-metal-jet technology. The 5 times higher contrast compared to the use of Cu-Kα radiation (8.0 keV photon energy) from a rotating anode X-ray source is caused by the fact that the energy of the Ga-Kα emission line is slightly higher than that of the Cu-K absorption edge (9.0 keV photon energy). The use of Ga-Kα radiation is of particular advantage for imaging of copper interconnects with dimensions from several 100 nm down to several 10 nm in a Cu/SiO2 or Cu/low-k backend-of-line stack. Physical failure analysis and reliability engineering in the semiconductor industry will benefit from high-contrast X-ray images of sub-μm copper structures in microchips.

Water aging effects on the flexural properties of fully biobased coir fiber composites

AbstractThis work describes the flexural behavior of biocomposites composed of a polyurethane matrix derived from castor oil plants and coir fibers. A statistical design is performed to identify the effects of fiber alkaline treatment and aging on the flexural modulus and strength of the composites. Physical tests and failure analyses are carried out to better assess their mechanical performance. A second experiment at 100% relative humidity is performed on treated fiber composites to compare with those obtained by immersion in water. The flexural modulus of the composites is not significantly affected by the fiber alkali treatment, while the strength is reduced by 35.17% when treated fibers are considered. Increasing the exposure time of composites under both aging conditions progressively reduces their flexural properties. The aging process of biocomposites in an environment with 100% relative humidity takes twice as long to reduce to the same flexural properties as those aged in water.Highlights Composites made with treated fibers showed higher apparent density and lower porosity. Water aging reduces flexural modulus and strength of biobased coir composites. The bending properties are strongly dominated by the properties of biobased polymer. 100% relative humidity takes twice as long to reduce to the flexural properties as those aged in water. Untreated coir fibers achieve superior bending properties under moisture aging.

Shift Left Quality Management System (QMS) Using a 3-D Matrix Scanning Method on System on a Chip

System-on-chip (SoC) quality management technology has been applied for a long time. During mass production, process defects and functional defects can have fatal consequences. However, in an SoC employing a high-coverage scan methodology, information from scan diagnostics can be used to locate failures and perform physical failure analysis (PFA) to improve production processes. PFA improves the overall production yield and leads to better quality control. However, since it is developed with deep sub-micron (DSM) processes, its complexity is high. It is difficult to accurately analyze data by merely collecting information from a single sample. PFA also involves high complexity associated with physical de-capping and analysis. To analyze all scan fail information, it is important to know which defect is the most critical and thus takes precedence. This has a large impact on the time to market, enabling the entire mass production process. In this brief, a 3D matrix scanning method is proposed, which can monitor product quality in real time during mass production. Using a quality management system, the results of two years of mass production have been shared. The problems encountered and the solutions to overcome these challenges during mass production have also been explained.

Millimeter-scale, Large Uniform Area Semiconductor Device Delayering for Physical Failure Analyses and Quality Control

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Failure mechanism of 4H-SiC junction barrier Schottky diodes under harsh thermal cycling stress

The concern in the long-term reliability of the SiC power devies is raised lately in power electronic field due to its brief history and limited data. In this work, discrete 1200 V/20A SiC JBS diodes have been intensively investigated by HTRB, HAST, and TCT. 2 % samples have failed in the harsh thermal cycling test, showing that the failure mechanism is attributed to field-oxide cracking. The electrical and physical failure analysis pointed out that a gradual degradation occurred at the termination structure, causing non-recoverable damages and provoking a significant increase in the leakage current. The FIB cut and SEM analysis showed the delamination existence between field oxide layer and silicon carbide layer in the degraded devices. The observed leakage current after the TCT could be well correlated with the formation of the delamination, which created a current leaking path between active and termination region. These findings emphasize the importance of SiO2/SiC interface quality in the long-term highly reliable SiC power devices, and indicate further optimized design of SiO2 passivation layer or other alternative materials is urgently needed to overcome this structural weakness.

Physical Properties and Failure Analysis for Bolts in the Diaphragm Valve by Micro Morphology and Metallographic Test

The reasons leading to the fracture of 17-4PH stainless steel bolts in the isolation valve of a power plant was analysed by means of morphology analysis, chemical analysis, hardness test, metallographic test, pitting corrosion test and intergranular corrosion test, SEM and other detection means. The results show that there are many corrosion pits on the surface of the valve stem in the seawater system, the corrosion pits is extend and propagation in intergranular cracking. The main reasons to valve stem fracture are the low corrosion resistance of the material and the improper aging process of heat treatment.

Search for copper diffusion at hybrid bonding interface through chemical and electrical characterizations

Cu/SiO2 diffusion at hybrid bonding interface without diffusion barrier was investigated in order to validate the electrical insulation of interconnects. The Cu thermal diffusion was studied by ToF-SIMS analysis of the dielectrics stack facing bonding pads after a bonding annealing (400 °C, 2 h) and a diffusion annealing (400 °C, 14 h). No trace of copper was found above the limit of detection 1017 at·cm−3. Cu ions drift was followed by I-V measurements on specially designed comb-serpentine that maximize the electrical field at bonding interface. Their efficiency was confirmed since physical failure analysis located the dielectric breakdown damage between bonding pads. Breakdown voltages coupled to wafer-to-wafer misalignments enabled the extraction of the SiO2 breakdown strength: 3.4 MV·cm−1. This study proves that at room temperature, hybrid bonding interconnects remain electrically insulated despite thermal budgets involved by the bonding process.

Open Localization in 3D Package with TSV Daisy Chain Using Magnetic Field Imaging and High-Resolution Three-Dimensional X-ray Microscopy

With the development of 3D integrated packaging technology, failure analysis is facing more and more challenges. Defect localization in a 3D package is a key step of failure analysis. The complex structure and materials of 3D package devices demand non-destructive defect localization technology for full packages. Magnetic field imaging and three-dimensional X-ray technology are not affected by package material or form. They are effective methods to realize defect localization on 3D packages. In this paper, magnetic field imaging and high-resolution three-dimensional X-ray microscopy were used to localize the open defect in a 3D package with a TSV daisy chain. A two-probe RF method in magnetic field imaging was performed to resolve isolation of the defect difficulties resulting from many different branches of TSV daisy chains. Additionally, a linear decay method was used to target sub-micron resolution at a long working distance. Multiple partition scans from a high-resolution 3D X-ray microscopy with a two-stage magnification structure were used to achieve sub-micron resolution. The open location identified by magnetic field imaging was consistent with that identified by a three-dimensional X-ray microscope. The opening was located on the top metal in the proximity of the fifth via. Physical failure analysis revealed the presence of a crack in the top metal at the opening location.

17.4: Invited Paper: Characterization and Failure Analysis of OLED devices by FIB/TEM Techniques

In this paper, we reported the application of TEM‐based techniques for the physical characterization and failure analysis of OLED devices. By using our new FIB‐TEM techniques, we successfully identified nanoscale multilayered organic film stacks in OLED devices, enabling the failure root understanding of the dark emission of R pixels in an OLD device. Other two case studies presented in this work demonstrated the importance of the combination of plane‐view FIB‐TEM with cross‐section FIB‐TEM techniques, and the grain size analysis techniques by TEM for the failure analysis of the OLED devices.

Advanced Physical Failure Analysis Techniques for Rescuing Damaged Samples with Cracks, Scratches, or Unevenness in Delayering

Advanced Physical Failure Analysis Techniques for Rescuing Damaged Samples with Cracks, Scratches, or Unevenness in Delayering

Fault recognition based test score for improving the accuracy of defect diagnosis

Diagnosis is an essential step to improve the yield in semiconductor manufacturing industry. It is performed on a failing chip to determine the location of defects. However, the defect diagnosis procedure may obtain too much candidate faults which lead to difficulties in next physical failure analysis. Recently, the methods based on test score to reduce candidate fault set are proved to be effective. The previous test score diagnosis method based on fault free information computes a score for each test which implies the fault identification ability. This letter proposes a novel fault recognition based test score for diagnosis which considers the fault identification capability of tests more comprehensively to improve the original method. More information provided by unique responses and faults detected of a test is added to evaluate the fault recognition for calculating a test score. Then the novel test score which takes more advantages of diagnostic information is applied to adjusting the fault score and reducing the candidate set. The experimental results show that the novel approach reaches smaller fault candidate set than the previous method and increases the diagnostic resolution and precision, and thus provides an effective improvement on the accuracy of diagnosis.

Diagnostic-driven yield engineering under atypical wafer foundry conditions

Typically, diagnostic-driven yield engineering consists of two sequential steps- data mining and failure analysis. Data mining seeks early feedback on suspected manufacturing process weakness while failure analysis reveals the physical defect to understand the root cause. However, under atypical conditions such as that in a wafer foundry environment, sufficient information is not available to attain optimal outcomes. Specifically, during volume data analysis, although Root Cause Deconvolution has the ability to predict process weakness using an unsupervised learning algorithm, it only works on random defects. Additionally, GDS layout of IP-secure product might also not be available to a foundry impeding physical failure analysis. Motivated by heightened demands on wafer foundries to deliver faster yield ramp to gain the competitive edge, this paper proposes solutions to overcome these limitations. An enhanced analytical scheme that offers early insights into process weakness (frontend and backend differentiation) regardless of fail mode, and a solution that enables physical failure analysis in the absence of direct access to GDS layout are proposed. An automated approach that captures image snapshots of suspected polygons without compromising confidentiality of the GDS content of IP-protected product is also developed. Experimental results will be presented as an illustration.

Mandibular reconstruction system reliability analysis using probabilistic finite element method

The aim of this study was to design for mandibular reconstruction of large lateral defect with minimum target reliability with designated confidence interval under bite force range of 300 ± 102 N. The performance of the models has been evaluated by numerical analysis considering the uncertainty of input parameters. Computer-Aided design was used to develop the models of three designs according to the patient's anatomy and to achieve to near symmetry of the mandible. Stress-strength modeling was utilized for the probabilistic physics of failure analysis under assumption of a quasi-static load. Monte-Carlo simulation was also applied for probabilistic finite element analysis and reliability assessment. The sensitivity analysis of the models was developed to reflect the significance of the variables in the models. The deterministic stress analysis shows that the highest stress and the second maximum stress are 110 MPa and 85 MPa for cortical bone around the screws, respectively. Also, it is determined that the maximum plate stress of the titanium conventional plate model is 580 MPa. The reconstruction system success rate was improved in all models by observing the anatomy of the patient's mandible in the plate designs by computer-aided design and additive manufacturing techniques. Based on the results, the reliability of plate strength and pull-out screws strength are 99.99% and 96.71% for the fibula free flap model, respectively, and 99.99% and 94.17%, respectively, for the customized prosthesis model. Probability sensitivity factors showed that uncertainty in the elastic modulus of the cortical bone has the greatest effect on the probability of screws loosening.

Direct Visualization of Breakdown-Induced Metal Migration in Enhanced Modified Lateral Silicon-Controlled Rectifiers

The robustness of electrostatic sensitive devices is important in state-of-the-art silicon technology. However, the electrical breakdown-induced microstructure evolution remains unclear. In this work, we performed the physical failure analysis of breakdown in an enhanced modified lateral silicon-controlled rectifier-based electrostatic discharge (ESD) device. Direct visualization of the conductive metal filaments in the doped silicon substrate has been achieved by high-resolution transmission electron microscopy. The locations of these metal filaments induced by breakdown are found near the cathode. The evolution of these microstructural changes and chemical properties provides guide to the failure analysis of ESD devices.

Recent progress of physical failure analysis of GaN HEMTs

Gallium nitride (GaN)-based high-electron mobility transistors (HEMTs) are widely used in high power and high frequency application fields, due to the outstanding physical and chemical properties of the GaN material. However, GaN HEMTs suffer from degradations and even failures during practical applications, making physical analyses of post-failure devices extremely significant for reliability improvements and further device optimizations. In this paper, common physical characterization techniques for post failure analyses are introduced, several failure mechanisms and corresponding failure phenomena are reviewed and summarized, and finally device optimization methods are discussed.

Low Voltage Time-Resolved Emission (TRE) Measurements of VLSI Circuit

Advanced technology nodes with small feature sizes and increased design complexity make it increasingly time-consuming to determine the root cause of yield loss. Several of the defects also occur inside a circuit making physical failure analysis (PFA) and electrical failure analysis (EFA) much more challenging. EFA has been instrumental in driving product yield and reliability for consumer products such as mobile phones and computer chips. It involves the use of state-of-the-art tools and techniques. One of the main changes EFA analyses is an enhancement of dynamic EFA in circuit failed in functional test. We propose a technique for advanced Electrical Failure Analysis (EFA) tool with a Superconducting Nanowire Single Photon Detector (SnSPD) system and its application to low voltage Time-Resolved Emission (TRE) measurements (also known as Picosecond Imaging Circuit Analysis, PICA) of scaled VLSI circuits with enhanced sensitivity for discussing Time Resolved Emission (TRE). In order to understand the figures of advantage that a single-photon detector should have to enable the acquisition of time resolved emission waveforms for low voltage applications. We will provide that measurements down to a low 1 V supply voltage were made possible by a careful optimization of the detector front-end electronics. We also characterized the emission from devices with different threshold voltages in order to understand how the emission contributions depend on this parameter and how this affects the resulting waveform. we hope to be able to show soon even better results that should allow continued application of the non-invasive TRE and PICA technology towards future scaled nodes with smaller gates and lower supply voltages.

Study on thermal, mechanical, microstructural properties and failure analyses of lanthanum zirconate based thermal barrier coatings: A review

This research study summarizes the recent information about the characteristics of multi layer and composite lanthanum zirconate based thermal barrier coatings (TBCs) that provide high-temperature thermal protection for the jet engines parts. Thus the outcome of lightweight gas turbine components able to work at 3000° F nearly 1650 °C needs to be built. Such difficulties can be solved using coatings with optimized microstructure and chemical composition. Recently, Lanthanum zirconate (La2Zr2O7-LZ) based pyrochlore oxides (Ra2Zr2O7, Re = rare earth) are now developing TBC material, owing to their fewer thermal conductivity with enhanced stability at elevated operating temperatures. Even though LZ cannot be directly replaced for standard YSZ because of its mismatch between the grew of thermal oxide (TGO) film. When LZ compared to Zirconia partially stabilized with yttria (YSZ), LZ possesses a poor thermal conductivity, lesser coefficient of thermal expansion, lower sintering ability, and lack of toughness than YSZ. Hence LZ comes to be combined with standard TBC YSZ in order to integrate advantages in multilayer architecture. In this study describes the thermal, mechanical and physical properties and failure analysis of Multilayer LZ/YSZ were described. It also reviews the characterization of coatings according to different criteria and conditions. At last, suggestions for investigation on layered LZ based TBCs applications for next-generation was indicated.

Reconfigurable Scan Architecture for High Diagnostic Resolution

Scan chain diagnosis is essential to solving yield-reduction problem caused by the miniaturization of manufacturing process. The accurate diagnosis of scan chain faults that frequently occur in the initial process is vital for rapidly improving yield. Moreover, the importance of scan chain diagnosis with a high resolution for the multiple faults is increasing because multiple faults occur in the early stages of the process, further increasing the cost of physical failure analysis. Although multiple faults can be diagnosed with existing methods, a high diagnostic resolution is difficult to achieve in the early stages of the process (where many faults occur) due to the rapid increase in the number of diagnosed fault candidates as the number of actual faults in the circuit increases. In this paper, a novel reconfigurable scan architecture that reconfigures the diagnosis paths and a test algorithm that uses this scan architecture are proposed to reduce the number of diagnosed fault candidates in the scan chain diagnosis with multiple circuit faults. Experimental results indicate that the proposed method achieves the higher diagnostic resolution for multiple faults than conventional methods. In addition, the proposed method reduces the routing overhead by scan partitioning.

CNN-Based Layout Segment Classification for Analysis of Layout-Induced Failures

Physical failure analysis (PFA) specifies layout designs that affect large-scale integration (LSI) failure. Because of their capability and cost-effectiveness, convolutional neural networks (CNNs) have been applied to LSI layout analysis. However, the information on failure for root cause analyses is generally limited. Moreover, information over a large area, which includes many geometries, is required to understand the effects of a layout on failure. These problems pose challenges in training the CNN models to achieve high accuracy for layout segment classification. In this study, we propose a scheme for layout segment classification that uses CNN to analyze the effects of layout on failure. Thus, multiple segment images of LSI layouts are used as inputs, and the outputs of CNN models are used to classify the input images as either risk or non-risk segments. First, we evaluated a simple 3-layer model, and then a 15-layer model fine-tuned using the transfer learning of the VGG16 model. The 15-layer model outperformed the 3-layer model for classifying the LSI layout segments. From a cross-validation of the 15-layer model, a true positive rate of >80% and a false positive rate of <10% are obtained for extracting layout regions related to actual defects. The outputs of the CNN models from the input layout segment demonstrate similarity with the defective layouts. In the regional layouts across the LSI chips, the contour plot of model outputs is visualized as a hazard map of failures. This information is necessary for additional failure cause analyses.

Laser Deprocessing Technique and its Application to Physical Failure Analysis

Laser Deprocessing Technique and its Application to Physical Failure Analysis