ESREF 2020: 31ST EUROPEAN SYMPOSIUM ON RELIABILITY OF ELECTRON DEVICES, FAILURE PHYSICS AND ANALYSIS
PROGRAM FOR WEDNESDAY, OCTOBER 7TH
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09:00-10:40 Session aJ: Modeling for Reliability
Location: Room A
09:00
Coupled simulations for lifetime prediction of board level packages encapsulated by thermoset injection moulding based on the Coffin-Manson relation
PRESENTER: Romit Kulkarni

ABSTRACT. A fibre orientation dependant material model of the thermoset is implemented to predict the lifetime of electronic components as a part of 2nd level encapsulated packages. Experimental data are used in combination with coupled simulations (process simulation – fibre orientation dependant material model – thermo-mechanical simulation) for defining this lifetime prediction model. An already existing lifetime prediction model based on the Coffin-Manson relation is used initially to evaluate the prediction accuracy. The prediction model is then adjusted and fitted for the current application.

09:20
Impact of Crystalline Orientation of Lead-Free Solder Joints on Thermomechanical Response and Reliability of Ball Grid Array Components

ABSTRACT. The microstructure of lead-free solder joints often consists of only one or a few randomly oriented tin grains as a result of conditions and reactions that take place during the solidification. Due to severe anisotropy of tin phase and this complex microstructure, the stress state of each joint will be unique, and lead to a dispersion in times to fail. This study aims at evaluating the impact of orientations of tin grains on the stress state of a BGA component. Different combinations of solder joint grain orientations are studied through thermo-mechanical simulations in order to assess the stress state of each joint.

09:40
Wear-out Failure of an IGBT Module in Motor Drives due to Uneven Thermal Impedance of Power Semiconductor Devices
PRESENTER: Ionut Vernica

ABSTRACT. In this paper, the uncertainties introduced by the variation of IGBT thermal impedance on the lifetime prediction of a motor drive IGBT module are investigated and quantified. A mission-profile-based reliability assessment procedure is first used to determine the reliability metrics of each IGBT in the inverter, according to its individual thermal impedance characteristic. Afterwards, the impact of thermal impedance on the power module reliability evaluation is quantified, and three study-case scenarios are analysed. The uncertainty analysis has shown that a significant deviation is expected in the lifetime prediction of motor drive IGBT modules, if the thermal impedance of each individual transistor is not carefully considered during the analysis.

10:00
A 3-D thermal network model for the temperature monitoring of thermal grease as interface material
PRESENTER: Xiaotong Zhang

ABSTRACT. Abstract –In order to study the influence of thermal grease applied as thermal interface material between IGBT (insulated gate bipolar transistor) module and heat sink on the junction temperature of IGBT module under long term load profiles, a 3-D thermal network based on thermal grease temperature monitoring is proposed. Firstly, the finite element simulation model of IGBT module and heat sink containing thermal grease is established. Then, considering thermal coupling effect, the temperature distribution of thermal grease is obtained and the temperature monitoring points of thermal grease are determined in the finite element simulation. Finally, a 3-D thermal network is established to monitor the temperature in all regions of thermal grease. The temperature distribution of thermal grease under long term load profiles is obtained and the influence of thermal grease degradation on the junction temperature of IGBT module is analyzed. The proposed 3-D thermal network model based on the precise monitoring of thermal grease can increase the accuracy of IGBT module reliability analysis.

10:20
Study of temperature dependence of breakdown voltage and AC TDDB reliability for thick insulator film deposited by plasma process
PRESENTER: Tatsuya Ohguro

ABSTRACT. In this paper, temperature dependence of breakdown voltage (Vbd) and time-to-failure (TTF) in TDDB for thick insulator film (300nm) deposited by plasma process are discussed. In SiO2 film used TEOS and O2 gases, increase of both Vbd and TTF beyond 100 ℃ is reported for the first time. On the other hand, in the SiO2 film and SiN film involving nitrogen, both Vbd and TTF decrease with increasing temperature. In order to explain these difference, we focused on the type of conductivity and introduced de-trapped effect by thermal energy. In the film used TEOS and O2 based SiO2 gases, the temperature dependence of number of trapped carrier is smaller because the conductivity type is the FN tunnelling, while the number of de-trapped carrier significantly increases with temperature and the TTF beyond 100 ℃ becomes longer. In the film involving nitrogen, the de-trapped effect is negligible because the number of trapped carrier exponentially increases with temperature like Poole-Frenkel conductivity.

09:00-10:40 Session bF3: Power electronic auxiliary circuits and system reliability
Location: Room B
09:00
Study of Moisture Transport in Silicone Gel for IGBT Modules
PRESENTER: Kaichen Zhang

ABSTRACT. In this paper, an original study on moisture absorption and desorption inside silicone gel for power modules is presented. Silicone gel from two suppliers has been cured at different conditions and exposed to a defined humid environment for a defined period of time. The mass of gel, the relative humidity and the temperature at a certain depth beneath the gel surface have been measured, and a permeability rate of the silicone gels has been calculated. For the two materials we observed significantly different changes in gel mass, but similar humidity levels deep inside the gel. We discuss the influence of curing and bake-out conditions as well as the difference in absorption and transport in the materials.

09:20
A time-domain stability analysis method for LLC resonant converter based on Floquet theory
PRESENTER: Hong Li

ABSTRACT. This paper establishes the closed-loop time-domain model for LLC resonant converter, and the stability analysis method based on Floquet theory is applied to LLC resonant converter for the first time. The closed-loop stability of LLC resonant converter is analysed according to the eigenvalues of the state transfer matrix of the model, and the stability range of control parameters are obtained. The accuracy and effectiveness of the stability analysis based on Floquet theory are verified by simulation platform in PSIM. Thus, a novel time-domain stability analysis method is provided for LLC resonant converter.

09:40
Modeling and Fault Diagnosis of Multi-phase Winding Inter-turn Short Circuit for Five-phase PMSM based on Improved Trust Region
PRESENTER: Jianwei Yang

ABSTRACT. Multi-phase PMSMs are widely used in fault-tolerant control applications. As an electrical fault with a high probability, inter-turn short circuit (ITSC) fault seriously affects the reliability of five-phase PMSM. However, due to high coupling of fault parameters, most of the fault models and diagnosis methods in fault-tolerant control focus on one-phase winding ITSC fault of three-phase PMSM. In this paper, a novel model and a fault diagnosis method are proposed for multi-phase winding ITSC (MPWITSC) of five-phase PMSM. First, by analyzing the related physical parameters of the motor, a mathematic model of MPWITSC fault is established. Then, a parameter estimation method based on improved trust region (ITR), which accelerates the convergence speed of traditional trust region (TTR) and reformulates the fault diagnosis as the extreme seeking for fault parameters is proposed to detect the ITSC fault level. Experimental results provide verification of the proposed model and fault diagnosis method.

10:00
Impact of Sensing Current Density on PN-Junction Based Temperature Estimation Methods for Si and SiC Power Devices
PRESENTER: Felix Hoffmann

ABSTRACT. In this work the impact of the sensing current density on the virtual junction temperature estimation methods for Si IGBTs and SiC MOSFETs using the pn junction voltage drop as TSEP was investigated. For this purpose, measurements of the temperature characteristics at different sensing current densities were performed on several Si and SiC devices. Additionally, TCAD simulations were performed to verify the measurement results. So far, 0.1% of the devices nominal current is commonly accepted as guideline for sensing currents for Si IGBTs and with the results of this investigation, this guideline was verified and examined towards their applicability for SiC MOSFETs. The results indicate that the 0.1% of the devices nominal current yield an applicable sensing current for Si IGBTs but is not applicable for SiC MOSFETs.

10:20
Multi-modal Fault-tolerant Control for Single-phase Cascade Off-gird PV-storage System with PV Failure Using Hybrid Modulation
PRESENTER: Yiyan Lu

ABSTRACT. An optimized fault-tolerant control for single-phase cascade off-grid photovoltaic(PV)-storage system with PV failure is proposed in this paper. Depending on states of PVs, the proposed fault-tolerant control utilizes operating modes analysis to enhance reliability of the system. The operating modes of normal running, partial PV failure, and full PV failure are analysed and control strategies for each mode is proposed respectively. Hybrid modulation is employed in all modes to reduce switching losses. The feasibility and effectiveness of the proposed control is validated by simulation results. The experiment results will be presented in the full paper.

09:00-10:50 Session cF2-2: Wide bandgap power Devices: GaN and Ga2O3 device level reliability - Invited Kornelius Tetzner
Location: Room C
09:00
Role of the AlGaN barrier on the long-term gate reliability of power HEMTs with p-GaN gate

ABSTRACT. Forward gate constant voltage stress (CVS) has been performed on 200 mm GaN-on-Si HEMTs with p-GaN gate, processed by imec with different gate process splits. In particular, the adoption of devices with a different magnesium (Mg) concentration, aluminum percentage (Al%) and AlGaN barrier thickness, allowed us to identify the degradation of the AlGaN barrier as responsible for time dependent gate breakdown at room temperature. In particular, lowering Al% and Mg concentration leads to a longer gate lifetime, while an optimum AlGaN barrier thickness is identified at given Al%.

09:20
Gate leakage current sensing for in situ temperature monitoring of p-GaN gate HEMTs

ABSTRACT. In this paper, an effective, yet simple, methodology for the temperature monitoring of voltage-driven p-GaN HEMTs based on gate leakage current sensing is presented. The proposed solution has been verified by SPICE ET simulations and experiments on commercial devices within and out of safe operating area (SOA). Moreover, the monitoring circuit can be effectively adopted for commercially available normally-off p-GaN HEMTs with no need of modifying the recommended gate driver circuit.

09:40
Non Thermally-Activated Transients and Buffer Traps in GaN Transistors With p-Type Gate: a New Method for Extracting the Activation Energy
PRESENTER: Arianna Nardo

ABSTRACT. This paper demonstrates that conventional drain current transient (DCT) measurements fail at identifying the correct activation energy of buffer defects in transistors with p-GaN gate. Based on combined pulsed and transient characterization, we demonstrate that (i) under off-state stress, the analysed devices suffer from moderate dynamic-Ron and from positive shift in the threshold voltage; (ii) the de-trapping kinetics, analysed by DCT, are unexpectedly not thermally-activated; (iii) de-trapping kinetics are significantly accelerated when measured at high gate voltage; (iv) we report a power law correlation between the gate leakage measured during the de-trapping phase and the time constant for recovery. Finally, (v) we propose a new characterization procedure, based on TLM structures, to overcome these issues that prevent accurate characterization of buffer-related effects.

10:00
OFF-state Trapping Phenomena in GaN HEMTs: Interplay Between Gate Trapping, Acceptor Ionization and Positive Charge Redistribution
PRESENTER: Eleonora Canato

ABSTRACT. We present an extensive analysis of the trapping processes induced by drain bias stress in AlGaN/GaN high-electron-mobility transistors (HEMTs) with p-GaN gate. We demonstrate that: (i) with increasing drain stress, pulsed I-V show an initial positive VTH variation and an increase in RON then, for drain voltages >100 V, VTH is stable and the RON shows a partial recovery. (ii) At moderate voltages, VTH instability is related to trapping at the gate stack, due residual negative charge left behind by the holes that leave the p-GaN layer through the Schottky gate contact and/or to trapping at the barrier. At higher voltages, we demonstrate the interplay of two trapping processes by C-V and pulsed drain current analysis: (iii) a fast storage of positive charge, accumulated in near the buffer/SRL interface, not strongly thermally activated, dominating at higher voltages; (iv) a slower negative charge storage, thermally activated.

10:20
Challenges to Overcome Breakdown Limitations in lateral β-Ga2O3 MOSFET Devices

ABSTRACT. Due to the large band gap of 4.8 eV and the resulting high breakdown strength of 8 MV/cm, the semiconductor material β-Ga2O3 has a very promising potential for next-generation power electronic applications. The higher breakdown strength compared to established technologies based on SiC or GaN allows a much more compact design of the transistor structures, which leads to reduced switching and conduction losses. This enables far more efficient, lighter and smaller power electronic converters to be implemented than it is possible today. In this talk the fabrication of high-performance metal-oxide-semiconductor field-effect transistors (MOSFETs) on Si-doped homoepitaxial layers on (100) Mg-doped semi-insulating β-Ga2O3 substrates is presented. The fabricated devices exhibit maximum drain currents, on/off-current ratios and ON-resistances of ~75 mA/mm,109 and 110 Ω·mm, respectively. Moreover, breakdown voltages at around 1200 V for devices with a gate-to-drain distance of 6 µ m are measured which equals an average breakdown field strength of 2 MV/cm. Further investigations on devices with and without field-plates reveal interface-related material inconsistencies which might represent the current main limitation factor in reaching high breakdown voltages in β-Ga2O3 MOSFET devices.

11:10-11:30 Session Industrial 2: Hitachi Power Solutions Co., Ltd.
11:10
High Throughput Ultrasonic Inspection Apparatus Using Quasi-static Water Surface Contact

ABSTRACT. Non-destructive testing of semiconductor devices and power modules is indispensable for safety and security society. We have developed high-speed ultrasonic inspection system for 100% inspection using an array transducer with a water fountain. The array transducer performs high-speed inspection by switching the transducer elements sequentially. The quasi-static water film is formed around the elements by the water fountain and contacts to the an inspection surface irradiating ultrasound. This system enables non-immersion inspection by which sample surfaces other than the inspection surface are kept dry. In our presentation, several inspection examples applied this system such as a silicon wafer and an IGBT module are demonstrated.

11:30-12:50 Session A-3: Quality and reliability assessment techniques and methods for devices and systems
Location: Room A
11:30
Comparative evaluation of mission profile based reliability assessment methods of power modules in motor drive inverter
PRESENTER: Ui-Min Choi

ABSTRACT. In this paper, the time-dependent reliability of the IGBT module obtained by Monte Carlo method from a certain Bx lifetime is compared with that estimated by the complete percentile lifetime model in the case study of motor drive inverter. The complete percentile lifetime model is developed by the power cycling test results of 30 IGBT modules.

11:50
Non-destructive Automatic Die-Level Defect Detection of Counterfeit Microelectronics using Machine Vision

ABSTRACT. Abstract –The goal of this paper is to automate the process of IC counterfeit detection using Non-destructive Imaging Techniques. The defects targeted in this study are the most prevalent die-level defects with possible multi-dimensional features, making their non-destructive detection challenging. Non-destructive X-ray microtomography is a powerful tool to obtain 3D internal information on microelectronics but usually results in large datasets and a stack of more than a thousand 2D images requiring a subject matter expert to investigate them individually for potential defects. Such a detection method is time-consuming, costly and subjective being largely dependent on the level of expertise, experience, and diligence. Our method addresses those challenges by incorporating machine vision instead of human input for detection.

12:10
Reliability test for Subsea Power Semiconductors
PRESENTER: David Guillon

ABSTRACT. Following the demand from a new domain of application, a test setup was developed to evaluate the performance of high-power semiconductor device when exposed to a dielectric liquid and high pressure. The specific test conditions were established to emulate the conditions inside a tank place in a deep-sea environment. Those conditions can be characterized by two key parameters: the pressure and the chosen dielectric/thermal liquid. The power semiconductor device is to be tested at high and low temperature to simulate operation under maximum load as well as when turned off, respectively. The reliability tests outlined here serve to support the development and the validation of Subsea technology for semiconductors power modules.

12:30
Combined Experimental and Numerical Approach for Investigating the Mechanical Degradation of the Interface between Thin Film Metallization and Si-Substrate after Temperature Cycling Test
PRESENTER: Dawei Zhao

ABSTRACT. The thin film metallization, as a key structure of the semiconductor devices, realizes the bond-ability of the chips on circuit carriers and directly influences the electrical and mechanical reliability of the interconnection. In a previous study, a recently developed method, cross-sectional nanoindentation (CSN), was utilized in order to characterize the adhesion strength degradation of the thin film metallization and its feasibility was proofed. In this paper, based on the now extended CSN test results from the previous study, a combined experimental and numerical approach with a cohesive zone model (CZM) has been developed in order to evaluate the adhesion strength degradation of the thin film metallization quantitatively by means of the critical strain energy release rate Gc. in order to obtain a measure with physical meaning and extrapolation ability.

11:30-12:50 Session bK-1: Radiation impact on circuits and systems reliability
Location: Room B
11:30
Experimental setup to monitor non-destructive single ionization events caused in power devices by terrestrial cosmic radiation.
PRESENTER: Marco Pocaterra

ABSTRACT. A dedicated experimental setup is presented for the acquisition of single ionization events occurring in power devices due to terrestrial cosmic radiation. This spectrometer chain is designed to be used for long-term experiments, where devices are submitted to the natural cosmic radiation, as well as for experiments using radioactive sources, and TCR tests. Every single ionization event that generates in the device charge pulses ranging from 1 fC up to 2 pC is recorded together with its time stamp and waveform. Original pile-up rejection strategies are implemented, which enable to acquire up to 40'000 events per second. The dedicated hardware and software are described in very detail in conjunction with the main operating procedures. Examples are presented, where the ionization events are classified, which occur in a SiC MOSFETs and in a Si Power diode during more than 30'000 hours operation.

11:50
Asynchronous early output majority voter and a relative-timed asynchronous TMR implementation
PRESENTER: Nikos Mastorakis

ABSTRACT. This paper presents a new asynchronous early output 3-input majority voter that is used to realize a high-speed, low power and less area occupying relative-timed asynchronous TMR implementation. The proposed majority voter is used to realize an example asynchronous TMR implementation, and similar asynchronous TMR implementations were realized using existing asynchronous majority voters. The dual-rail code was used for data encoding and two kinds of four-phase handshaking were considered for data communication. Compared to the best of the existing implementations, on average, we find that the proposed majority voter leads to an efficient asynchronous TMR implementation by simultaneously reducing the cycle time, silicon area, and average power dissipation by 25.1%, 7.5% and 7.8% respectively. The implementations used a 32/28nm CMOS technology.

12:10
Physical Mechanisms for Gate Damages Induced by Heavy Ions in SiC power MOSFET

ABSTRACT. The objective of the paper is to present a trap assisted tunnel conduction mechanism able to explain the creation of a conductive path in the gate oxide of SiC power MOSFET during the impact of heavy ions. The consequent large current flow through the oxide can induce damages to the gate structure. The model is based on the results of 2D finite element simulation and is supported by previous works dealing with trap assisted tunneling hole injection in silicon dioxide.

12:30
Improving GPU register file reliability with a comprehensive ISA extension

ABSTRACT. This work proposes a comprehensive ISA extension to improve GPU reliability to transient effects. Three additional instructions are proposed, implemented, and combined with software-based datapath duplication. Modified program codes are compared to state-of-the-art software-based fault tolerance techniques in terms of execution time, the circuit area is evaluated against the original GPU architecture, and a fault injection campaign is performed to assess reliability. Results show that the proposed ISA extension improves the performance of software-based approaches while maintaining fault detection capabilities at negligible costs in the circuit area. This work can help engineers in designing more efficient and resilient GPU architectures.

11:30-12:50 Session cG-2: MEMS
Location: Room C
11:30
Can automotive MEMS be reliably used in space applications? An assessment method under sequential bi-parameter testing
PRESENTER: Maxime Auchlin

ABSTRACT. Commercial Off-The-Shelf (COTS) automotive inertial measurement units were subjected to severe accumulative stress conditions: thermal shocks (high temperature gradients), temperature cycling (low gradients) and mechanical vibration are combined in an A-then-B sequential testing procedure, with the aim to promote failure acceleration and improve lifetime prediction. The maximum stresses, applied individually, did not cause failure on the selected components. On the other hand, accumulative bi-parameter testing conditions resulted in die attach delamination. Three batches of devices tested with different preconditioning (A-then-B or B-then-A) display different reliability figures. Failure mode and effects analysis (FMEA) is established. A Finite Element Analysis (FEA) is done based on a destructive physical analysis of the devices to confirm the correlation between the stresses applied and the physics of the failure in order to understand the thermomechanical behaviour of the devices, linking it to observed failures.

11:50
Robustness of a M&NEMS Pressure Sensor up to 522°C

ABSTRACT. This paper examines the reliability of pressure sensors fabricated with the M&NEMS technology up to 522°C. The results are quite promising as we observe only a small decrease (6%) of the sensor sensitivity after thermal cycling. The packaging of the sensor seems to well withstand these temperatures and the only limit that is identified is the metallization of the pads which could be improved in order to have functional devices at higher temperatures.

12:10
A study of material stoichiometry on charging properties of SiNx films for potential application in RF MEMS capacitive switches

ABSTRACT. This work presents an in depth investigation regarding the effect of PECVD silicon nitride (SiNx) stoichiometry on its charging properties. The investigation took place in SiNx dielectric films with different Si-content (x=0.47-1.04). Thermally Stimulated Depolarization Currents (TSDC) as well as a single-point Kelvin probe (KP) System have been used in Metal-Insulator-Metal (MIM) capacitors, with the same charging conditions, in order to determine the total injected charge and the charge that was displaced through the bulk of each SiNx material. The experimental results revealed that the increase of Si-content results to an increase of dielectric charging but the injected charges are displaced faster through the bulk material and towards the bottom electrode. Finally, the effective temperature is used in order to investigate hopping conduction that dominates charge transport in the bulk material and thus a more realistic approach of the discharging process is presented.

12:30
Field emission induced-damage in the actuation paths of MEMS capacitive structures
PRESENTER: John Theocharis

ABSTRACT. The paper analyses for the first time the electrical discharges across the actuation paths in MEMS capacitive structures. Electric fields beyond the field emission region were applied and under different pressure levels below the atmospheric one. The current-voltage characteristics reveal a stable field emission followed by a noisy one and a region of plasma discharge that causes severe damage to actuation paths. Finally, the experimental results reveal a progressive damage with the current increasing.

13:20-13:40 Session Industrial 3: Sector Technologies SAS
13:20
ThermoFisher Static Optical Fault Isolation Roadmap and Lock- In Thermography for Automotive

ABSTRACT. After a short overview of the ThermoFisher Optical Fault Isolation solutions roadmap focused on static Failure Localization, we will focus on use cases using Lock In Thermography applied to the Automotive Electronics. Nowadays, the automotive market challenges are pushing for fuel efficiency and Advanced Driver Assistance Systems which demand to automotive electronics more complex and sophisticated electronics systems. In the same time, this industry is always expecting to maintain the highest standards of reliability. Considering these two antagonist criteria, most advanced techniques need to be introduce it the reliability/Failure analysis flow to ensure high reliability level of car electronics Two of the main benefits of this technique are the total non destructive approach as well as the real flexibility in term of Device Under Test (from electronic assembly down to single chip). These characteristic make LIT very suitable for the automotive market on which these prerequisites are definitely mandatory.

13:40-14:00 Session Industrial 4: SmarAct GmbH
13:40
Presentation of the new SMARPROBE LX nanoprober system

ABSTRACT. Due to the ever shrinking size of transistor technology nodes the task of nanoprobing becomes more and more ambitious. Addressing this issue SmarAct GmbH expands the existing SMARPROBE nanoprobing platform with the new SMARPROBE LX nanoprober, aversatile closed-loop positioning system with an active temperature control and an extended scan range. In this presentation it will be shown how the closed-loop positioning allows the user to position the tips to the point-of-interest in very short time and with as little electron beam exposure as possible.

14:00-15:30 Session Poster 3a: B - Failure mechanisms and reliability of micro- and nanoelectronics
Location: Poster Room
14:00
Row hammer avoidance analysis of DDR3 SDRAM
PRESENTER: Martin Versen

ABSTRACT. A DDR3 SDRAM test setup implemented on the Griffin III ATE test system from HILEVEL Technologies is used to analyse the row hammer bug. Row hammer pattern experiments are compared to standard retention tests for different manufacturing technologies. The row hammer effect is depending on the number of stress activation cycles. The analysis is extended to an avoidance scheme with refreshes similar to the Target Row Refresh scheme for the DDR4 SDRAM technology.

14:00
Reliability Prediction of FinFET FPGAs by MTOL
PRESENTER: Emmanuel Bender

ABSTRACT. Abstract – The MTOL (Multi-Temperature Operational Life) testing method was implemented on FPGA boards from Xilinx 16nm FinFET technology using non-aggressive stress conditions. The study shows that, compared to HCI and EM, BTI is the dominant mechanism. The testing shows a slight, linear increase in degradation with the increase of frequency. Strong evidence shows that the effect is due to self-heating of the Fins. The temperature increase, due to current induced self-heating caused by high frequency, was tested up to 1 GHz and extrapolated to 3 GHz. The results of this study have significant implications in that we fully characterize the total reliability of FinFET devices over their lifetime.

14:00
AC stress reliability study on a novel vertical MOS transistor for non-volatile memory technology
PRESENTER: Jordan Locati

ABSTRACT. Abstract – This paper presents a novel high voltage vertical trench MOS transistor designed to be used in a Non-Volatile Memory (NVM) technology. Physical and electrical measurements are carried out to understand the device behaviour. The comprehension is supported by TCAD simulations. Finally, the AC stress reliability results are reported.

14:00-15:30 Session Poster 3b: C - Progress in failure analysis: defect detection and analysis
Location: Poster Room
14:00
Novel Failure Traces beyond the Barrier on the Floating Device
PRESENTER: Gwang Wook Lee

ABSTRACT. Failure Analysis (FA) on Fully Depleted Silicon On Insulator (FDSOI) device is challenging due to its unique structure with buried oxide layer. Based on the in-depth study on structural limitation of the device, this paper firstly reports novel approaches for the physical and electrical FA methodologies with the success stories for yield learning. Furthermore, we demonstrate the improvements of FA methods compared to the conventional ones and how new ideas are applied to the analysis procedure.

14:00
Ultrasonic monitoring performance degradation of lithium ion battery
PRESENTER: Jang-Hun Jo

ABSTRACT. To monitor the performance and reliability of a lithium-ion battery during charge/discharge cycles, an ultrasonic time-of-flight (ToF) and attenuation measurement was performed. Ultrasonic ToF of the reflected pulse echo increased with the decrease in the state of charge (SoC) and with the increase in number of cycles (i.e., degradation). A health evaluation map relating SoC with ToF at various cycles was constructed. In this map, ultrasonic hysteresis was reported, of which area reflected the magnitude of irreversible electrochemical damage to the battery material. A linear correlation between the ToF and the number of cycles was observed.

14:00
Failure-analysis method of soldering interfaces in light-emitting diode packages based on time-domain transient thermal response
PRESENTER: Byongjin Ma

ABSTRACT. New soldering-interface failure-analysis method based on the transient thermal of the LED packages are proposed. This method is based on a physical property that the change of the junction temperature, which is monitored by voltage, represents the change of thermal gradient in the LED packages. Fast time-domain algorithm for failure-sensitivity enhancement was developed. And the feasibility of this algorithm was verified using a two-point measurement method during a thermal shock test.

14:00
Correlative microscopy workflow for precise targeted failure analysis of multi-layer ceramic capacitors
PRESENTER: Nicholas May

ABSTRACT. Abstract –The correlative framework includes three-dimensional X-Ray tomography, femto-second laser micro machining, three-dimensional FIB/SEM/EDS tomography, and data segmentation. This framework is highly efficient allowing non-destructive locating of the defect and nanometer precise targeting with communication between instruments. The analyses resulted in a fully segmented three-dimensional data set revealing a failure mode of leakage due to suspended metal within the dielectric material.

14:00-15:30 Session Poster 3c: E - Packaging and assembly reliability and failure analysis
Location: Poster Room
14:00
Effects of anisotropy on the reliability of TSV microstructure
PRESENTER: Zhengwei Fan

ABSTRACT. This article explored in detail the influence of the anisotropy of silicon and copper on the reliability of TSVs, and particularly focused on the coupled effect of anisotropic of silicon and copper. In addition, the influence of copper plasticity was also analyzed. The results show that a strong anisotropy will significantly increase the crack propagation capability at the structural interface and threaten device reliability. And the anisotropic coupling effect of copper and silicon will further amplify the impact. Besides, the plasticity of TSV-Cu cannot be ignored in the analysis of the reliability of the TSV structure as it has a significant effect on the crack growth.

14:00
Reliability improvement for palladium coated copper wire using additive element
PRESENTER: Motoki Eto

ABSTRACT. In this paper, we investigate the corrosion behaviour of Cu9Al4 with and without Pd and additive element, clarifying the effect of Pd and additive element on the corrosion resistance of Cu-Al IMC. Furthermore, improving mechanism against pitting corrosion under high temperature storage life test is also discussed with microstructure analysis. The result shows that additive element forms protective passivation layer on the IMC and Cu surface.

14:00
Robustness Evaluation Of PCB-Embedded Power Dies Using Solderless Pressed Metal Foam
PRESENTER: Said Bensebaa

ABSTRACT. This paper presents reliability analysis of an innovative process of embedding power dies in PCBs. Firstly, a description of this solderless package is given. Secondly, experimental investigations of thermal aging for the proposed package are performed through passive thermal cycling in the range of PCB standards. Then 3D simulation model of the package is created using material properties obtained from thermo-mechanical characterizations which realized in previous studies.

14:00
Remaining Useful Lifetime estimation for Electronic Power modules using an analytical degradation model
PRESENTER: Mohamad Nazar

ABSTRACT. 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 modules failure, one should assess its reliability in real-time operation. For this purpose, Prognostics and Health Management (PHM) approach could be a promising tool for reliability evaluation. In this paper, we propose an analytical model that describes the metallization to wire-bond contact degradation, which is a main cause that leads the IGBT power module to fail. The usual aging indicator of such damages is the collector-emitter voltage (V_CE) 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 prognostic model for estimating the remaining useful lifetime (RUL) of IGBT power modules. The prognostic model is illustrated using aging data coming from accelerated power cycling tests with different stress conditions. Results show a prognostic capability.

14:00
Effects of Solder Degradation on the Die Temperature Measurement via Internal Gate Resistance
PRESENTER: Julio Brandelero

ABSTRACT. Virtual junction temperature measurement via internal gate resistance(Tvg) is attractive for the health monitoring of the power modules. Using the gate resistance as TSEP permits precise and timely absolute temperature on the die where the gate is located. This paper investigates how this measurement relates to other parts of the power die, inclusive of ageing effects such as die attach degradation. A model has been developed to describe the temperature distribution, validated through FEM simulations and experimental measurements.

14:00
Interface characterization of Cu-Cu ball bonds by a fast shear fatigue method
PRESENTER: Bernhard Czerny

ABSTRACT. A highly accelerated shear fatigue testing method is presented to test the long-term reliability and reveal the bonded interface of thermosonic Cu-Cu ball bonds. The method is an adaptation to a new industrial fatigue tester (BAMFIT) and can be conducted without an intricate specimen preparation. This method induces one-directional mechanical cyclic shear stresses to the Cu nailhead in order to initiate fatigue fracture until lift-off, revealing the actual bonded interface. This study compares the fatigue resistance of Cu wire to coarse and fine grained Cu and Al metallization. The fatigue results are accompanied by nano indentation tests and shear tests. The fatigue results showed the best performance for those bonded on coarse grained Cu pads (metallization), slightly less for fine grained Cu and at least a decade more than Cu-Al. Annealing the specimens prior to testing resulted in a slightly increases in Nf for Cu bonds on fine grained pads as well as for Cu-Al bonds. The Nf for coarse grained Cu pads remains the same but the scattering of the fatigue results increases. With the ability to compare the fatigue behaviour of the bonded interface within minutes, this method is most suitable for rapid qualification at an early stage of development.

14:00
Using of Bond-Wire Resistance as Ageing Indicator of Semiconductor Power Modules
PRESENTER: Ali Ibrahim

ABSTRACT. This paper studies the use of wire—bonds contact resistance as indicator to diagnose the health state of power electronics modules. This technique is especially dedicated to monitoring the degradation of the topside interconnection (metallization-wire bonds) when the module is wired with a Kelvin point. The main advantage of this indicator is that it can be followed online, without being disturbed by current or voltage, to diagnose the health state of the power module and, possibly, the prognosis of the remaining lifetime of the power module by associating it with a lifetime model. For this purpose, based on power-cycling tests in different conditions, a comparison between this indicator and the one commonly used, i.e. the collector-emitter voltage Vce, show that the first one is much more sensitive to the degradations, easier to use online and finally should be more suitable for lifetime prognosis.

14:00
Packaging Reliability Estimation of High-Power Device Modules by Utilizing Silver Sintering Technology
PRESENTER: Chi-Wei Wang

ABSTRACT. In this study, a high-power device packaging composed of 600V/450A insulated gate bipolar transistor module is presented. To improve the thermal dissipation and decrease the junction temperature, the Ag paste sintering approach is applied instead of the conventional soldering processes. After conducting a thermal cycling test of up to 2000 cycles, the die shear strength of the sintered Ag is as high as 24.8 MPa. Lowering the induced stress to fracture failure is carefully suggested using finite element simulation. Furthermore, a reduction of –22% in the thermal resistance is measured. This research demonstrates that the application of the Ag paste sintering method in the 600V/450A insulated gate bipolar transistor module is dramatically useful.

14:00
Influence of Temperature and Humidity on Power Cycling Capability of Power Modules
PRESENTER: Felix Wuest

ABSTRACT. Since power electronics becomes more and more important for harsh environments, its power cycling capability under these conditions needs to be known. The goal of this research is to identify how high temperature and humid environments contribute to the damage of power modules during power cycling. Therefore, IGBT modules are tested with power cycling in cold environment, hot, dry environment and hot, humid environment. Additionally, High Humidity High Temperature Reverse Bias testing is done for comparison of different failure mechanisms. Power modules under warm, humid conditions fail significantly earlier than in warm, dry, or even cold, dry environment. This is mainly attributed to two effects. Firstly to the moisture swelling and thermal expansion of the housing material at higher temperatures and humidity which have an influence on the pressure on the thermal interface and secondly the moisture uptake capability of the thermal interface material.

14:00-15:30 Session Poster 3d: G - Optoelectronics, Micro-Electro-Mechanical actuators and MEMS
14:00
Barrier properties analysis of Cu/TiW/ITO electrode for Si heterojunction solar cell under thermal aging

ABSTRACT. The front side metallization of silicon heterojunction (SHJ) solar cell was fabricated by electroless copper plating. The front electrode was composed of a copper/copper seed/TiW/ITO structure applied TiW layer as a diffusion barrier. In this paper, it was investigated the changes of TiW diffusion barrier under environmental stress. To analyze the barrier stability of TiW, samples for aging were fabricated by depositing copper seed/TiW/ITO on glass. The environment stress was applied to stress of the thermal aging (85ºC /1,000 hr). The stability of layer structure was analyzed by TiW thickness split (20nm, 50nm, 100nm) under environmental stress. Thermal oxidation on copper seed surface was depend on TiW thickness. The Cu2O phase was mainly formed with increase of TiW thickness. ITO diffused towards copper seed through TiW.

14:00-15:30 Session Poster 3e: H - ESD, EOS, Latch-up, EMC-EMI in integrated and power circuits
Location: Poster Room
14:00
Conducted EMI mitigation in transformerless PV inverters based on intrinsic MOSFET parameters
PRESENTER: Kraiem Sana

ABSTRACT.  Electromagnetic interferences (EMI) caused by the high switching frequency of power semiconductors in transformerless single-phase grid-connected photovoltaic (PV) inverters have adverse effects on the lifetime of PV cells and reliability of the electronic and domestic equipment in the neighborhood of the PV installation. This paper proposes a design methodology that helps electronic circuit designers reduce EMI in single-phase PV inverters involving a large number of power semiconductors. Firstly, the most disturbing sources (switching cells) in terms of EMI are identified. Thereafter, a careful choice of the Si-MOSFET assigned to these sources is performed based on its intrinsic parameters. The method is applied to an H5 PV inverter and validated with numerical simulations and experimental tests. The obtained results show a decrease in the conducted EMI after the identification of the disturbing source and the selection of the Si-MOSFET with appropriate intrinsic parameters. 

14:00
Experimental results on gated diodes and BIMOS ESD devices in 28nm FD-SOI under TLP & TID radiation
PRESENTER: Philippe Galy

ABSTRACT. The electrostatic discharge (ESD) protection is a major concern for advanced CMOS technology manufacturing.Several solutions are available on market with efficient robustness and compliant with the ESD window especially in 28 nm FD-SOI technology. In the framework of harsh environment applications and to explore the performance under total ionizing dose (TID) radiation, it is important to investigate ESD protection devices such as gated and STI diodes in hybrid bulk or BIMOS solution in thin silicon film. This study is based on transmission line pulse (TLP)characterization before and after Co60 TID radiation in the range of [25 krad – 200 krad]. Following this analysis, we expect to gain better understanding of robustness and push the final performance of the device. The preliminaryresults will be useful to give a trend and to improve the device robustness against ESD and TID events and lead to more competitive solutions.

14:00
Conducted EMI Susceptibility Analysis of a COTS Processor as Function of Aging
PRESENTER: Fabian Vargas

ABSTRACT. This work analyses the conducted electromagnetic immunity (EMI) of the Cortex-M4 processor as function of aging. Voltage dips were injected in the VDD input power pins of the processor as ruled by the IEC 61000-4-29 standard, whereas aging test was performed by means of the 1015.9 Burn-In Part of the Method MIL-STD-833E. We observed that after 456 hours at 125°C, the processor presented a current increase in excess of 2.36%, an average increase in the conducted EMI susceptibility in the order of 38% and negligible performance degradation according to the Dhrystone V2.1a benchmark.

14:00-15:30 Session Poster 3f: L - Batteries, capacitors & passives
Location: Poster Room
14:00
A power transfer model-based method for lithium-ion battery discharge time prediction of electric rotatory-wing UAV
PRESENTER: Mengtong Gong

ABSTRACT. Abstract – This paper develops a power transfer model-based method to estimate real-time state of energy (SOE) and predict end of discharge (EOD) time of rotatory-wing UAVs lithium batteries under dynamic operational conditions. A discrete-time state-space model of battery is first established to model the process of battery power consumption and establish a mapping of battery unobservable state of energy (SOE) to measurable parameters such as voltage and current. Then a power consumption model of UAV is established based on predetermined flight mission of UAV using aerodynamics and momentum theory, which estimates power consumption of UAV under different operational conditions. Its calculation results can be directly used in battery state-space model as its input. Finally, a Particle Filter (PF) approach with Adam optimization algorithm is developed to estimate SOE and predict EOD time on-line, and better prediction results compared to conventional PF are achieved. Real experiments on UAV verify the effectiveness of the proposed method.

14:00
Reliability analysis of excitation control modes of a synchronous condenser during grid-integration at the speed-falling stage
PRESENTER: Tao Yuan

ABSTRACT. As a kind of reactive power compensation equipment, a synchronous condenser has advantages of strong overload capacity and effective suppression of commutation failures. It has been widely used in AC/DC power transmission systems. In this paper, the excitation control modes of the synchronous condenser during grid-integration at the speed-falling stage are studied with three contributions: (1) The necessity of using the exciter at the speed-falling stage and the associated excitation control characteristics are analysed. The dynamic behaviours with different mono-excitation-control modes are compared with identification of the merits and drawbacks. (2) In order to smooth the voltage rising curve during the stator voltage establishment at the speed-falling stage so as to enhance the reliability of starting the synchronous condenser, a sequential hybrid control scheme is proposed with PID controller for excitation at the initial and final stage, and for constant excitation at the middle stage. (3) In order to mitigate the oscillations during grid-integration, a control scheme of pre-insertion of an energy-absorption impedance (EAI) is proposed. The effectiveness and superiority of the proposed sequential hybrid excitation control mode with pre-insertion of an EAI for smoothing the voltage rising curve and mitigation of the oscillations are justified by the simulation results in PSCAD/EMTDC.

14:00
A Method to Extract Lumped Thermal Networks of Capacitors for Reliability Oriented Design
PRESENTER: Paolo Cova

ABSTRACT. In this work we propose a procedure based on finite elements simulations to compute a lumped-parameter thermal model of capacitors. The extracted Foster, or Cauer network coupled to the electrical model can be useful to evaluate the temperature of capacitors in SPICE-like simulations. In this way, it is possible to evaluate the expected maximum operative temperature of the capacitor embedded in a circuit before its real application, avoiding unexpected failures since the prototyping stage. Here, we describe the workflow of the method and, finally, the proposed approach will be used for the design of snubber capacitors to be used in a medium power (60 kW) high frequency AC/AC converter.

14:00
Health monitoring of mechanically fatigued flexible lithium ion battery by electrochemical impedance spectroscopy
PRESENTER: Jin-Yeong Kim

ABSTRACT. For reliable applications of flexible lithium ion batteries, the states of mechanically fatigued batteries were evaluated by applying electrochemical impedance spectroscopy (EIS). The EIS resistance of the batteries increased with mechanical fatigue, and this tendency was more distinct for the battery in the charged state. The EIS resistance of the fatigued battery was unstable and fluctuated during subsequent storage time after fatigue. Capacity degradation of the fatigued battery was about three times faster than that of the as-received one. By scanning electron microscopic observation of the dissembled electrode materials, root causes of the observed faster degradations were attributed to lithium metal precipitation on the carbon negative electrode as well as collapse of lamellae structures of the polymer separator (i.e., blockage of micro pores for lithium ion movement.)