Sebastian Brand

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• Ph.D.
• Head of Team at Fraunhofer Institute for Microstructure of Materials and Systems

The paper discusses enhancements in quantitative thermal lock-in analysis through spatial phase evaluation for defect localization in complex microelectronic components. It addresses the challenges of increasing integration density and diverse material composition in microelectronics. The primary focus of the present work is placed on improving sen...

The die-attach layer is a vulnerable structure that is important to the reliability of an insulated-gate bipolar transistor (IGBT) module. A new failure mechanism named fatigue crack network (FCN) has been identified in the central area of the IGBT modules' solder layer. In this paper, to investigate the formation mechanism of the FCN, a fast power...

This work demonstrates the capability of E-beam probing, combined with optical techniques, to effectively monitor the activity of the IC structures and extract the signals from a 16nm technology device through the silicon backside. We conducted optical probing to localize the area of interest on the device, where we aimed the E-beam probing to gath...

Presentation slides for the ISTFA 2024 Tutorial session “Machine Learning in Semiconductor Failure Analysis: Techniques and Case Studies.”

Non-destructive inspection and analysis techniques are crucial for quality assessment and defect analysis in various industries. They enable for screening and monitoring of parts and products without alteration or impact, facilitating the exploration of material interactions and defect formation. With increasing complexity in microelectronic techno...

Optical probing methods through the chip backside have been demonstrated to be powerful attack techniques in the field of electronic security. However, these attacks typically require specific circuit conditions, such as enforcing gate or register switching at certain frequencies or repeating measurements over multiple executions to achieve an acce...

Localizing security-relevant hard blocks on modern System-on-Chips for physical attacks, such as side-channel analysis and fault attacks, has become increasingly time-consuming due to ever-increasing chip-area and -complexity. While this development increases the effort and reverse engineering cost, it is not sufficient to withstand resolute attack...

Presentation slides for the ISTFA 2023 Tutorial session “Machine Learning Based Data and Signal Analysis Methods for the Application in Failure Analysis (2023 Update).”

Contactless probing methods through the chip backside have been demonstrated to be powerful attack techniques in the field of electronic security. However, these attacks typically require the adversary to run the circuit under specific conditions, such as enforcing the switching of gates or registers with certain frequencies or repeating measuremen...

Non-destructive inspection and analysis techniques are crucial for quality assessment and defect analysis in various industries. They enable for screening and monitoring of parts and products without alteration or impact, facilitating the exploration of material interactions and defect formation. With increasing complexity in microelectronic techno...

Presentation slides for the ISTFA 2023 Tutorial session “Non-Destructive Defect Localization by Scanning Acoustic Microscopy.”

Localizing security-relevant hard blocks on modern System-on-Chips (SoCs) for physical attacks, such as sidechannel analysis and fault attacks, has become increasingly time-consuming due to ever-increasing chip-area and - complexity. While this development increases the effort and reverse engineering cost, it is not sufficient to withstand resolute...

Electronic Device Failure Analysis Technology Roadmap examines the trends shaping the future of semiconductor technology as well as the tools and techniques that will be required to detect, analyze, and remediate failures. The information is organized into ten chapters, seven of which assess the capabilities, limitations, and future needs of fault...

Electronic Device Failure Analysis Technology Roadmap examines the trends shaping the future of semiconductor technology as well as the tools and techniques that will be required to detect, analyze, and remediate failures. The information is organized into ten chapters, seven of which assess the capabilities, limitations, and future needs of fault...

This presentation is an introduction to machine learning techniques and their application in semiconductor failure analysis. The presentation compares and contrasts supervised, unsupervised, and reinforcement learning methods, particularly for neural networks, and lays out the steps of a typical machine learning workflow, including the assessment o...

This presentation provides an overview of lock-in thermography and its application in semiconductor failure analysis. It begins with a review of direct thermal imaging, IR transmission and detection, and the fundamentals of lock-in measurements. It compares and contrasts steady-state IR imaging with lock-in thermography and shows how lock-in freque...

The paper presents the approach of enhancing time-domain signal analysis using machine learning techniques for analyzing acoustic echo signals and the subsequent derivation of condition-related class assignments for failure analysis. The examples provided here include two types of flip-chips with defects intentionally induced by thermal stressing....

Die Mikroelektronik ist zu einem unverzichtbaren Bestandteil unseres Lebens geworden und eine Schlüsseltechnologie der fortschreitenden Digitalisierung und Vernetzung unserer Gesellschaft. Der rasant zunehmende Einsatz von Elektroniksystemen in kritischen Infrastrukturen, für Industrie 4.0 oder Anwendungen im Internet of Things (IoT), der Kommu...

This presentation is an introduction to machine learning techniques and their application in semiconductor failure analysis. The presentation compares and contrasts supervised, unsupervised, and reinforcement learning methods, particularly for neural networks, and lays out the steps of a typical machine learning workflow, including the assessment o...

Lock-In Thermography is an established non-destructively operating method for the analysis of failures in microelectronic devices. In recent years a major improvement was achieved allowing the acquisition of the time-resolved temperature responses of weak thermal spots that enhances defect localization in 3D stacked semiconductor architectures. The...

This article describes a form of lock-in thermography that achieves 3D localization of thermally active defects in stacked die packages. In this approach, phase shifts associated with thermal propagation delay are analyzed as a function of frequency. This allows for a precise localization of defects in all three spatial dimensions and can serve as...

This paper discusses the implementation of GHz-Scanning Acoustic Microscopy (GHz-SAM) into a wafer level scanning tool and its application for the detection of delamination at the interface of hybrid bonded wafers. It is demonstrated that the in-plane resolution of the GHz-SAM technique can be enhanced by thinning the sample. In the current study t...

Signal processing and data interpretation in scanning acoustic microscopy is often challenging and based on the subjective decisions of the operator, making the defect classification results prone to human error. The aim of this work was to combine unsupervised and supervised machine learning techniques for feature extraction and image segmentation...

Lock-in thermography (LIT) has been successfully applied in different excitation and analysis modes including classical LIT, analysis of the time-resolved temperature response (TRTR) upon square wave excitation and TRTR analysis in combination with arbitrary waveform stimulation. The results obtained by both classical square wave- and arbitrary wav...

Purpose: To describe the application of scanning acoustic microscopy in the GHz-range (GHz-SAM) for qualitative imaging and quantitative characterization of the micromechanical properties of the Descemet's membrane and endothelial cells of cornea tissue. Methods: Investigated were samples of a normal tissue and a tissue with Fuchs' endothelial d...

GHz scanning acoustic microscopy (GHz-SAM) was successfully applied for non-destructive evaluation of the integrity of back end of line (BEOL) stacks located underneath wire-bond pads. The current study investigated two sample types of different IC processes. Realistic bonding defects were artificially induced into samples and the sensitivity of th...

This paper demonstrates the application of GHz-SAM for the detection of local non-bonded regions between micron-sized Cu-pads in a wafer-to-wafer hybrid bonded sample. GHz-SAM is currently the only available non-destructive failure analysis technique that can offer this information on wafer level scale, with such high resolution.

Engineers at the Fraunhofer Institute for Microstructure of Materials and Systems built and are testing a scanning acoustic microscope (SAM) that operates at frequencies of up to 2 GHz. Here they describe the design of their GHz-SAM and present examples showing how it is used to detect stress induced voids, inspect wire bond interfaces, and examine...

Through silicon via (TSV) is the most promising technology for vertical system integration and novel 3-D chip architectures. Reliability and quality assessment necessary for process development, root-cause analysis, and manufacturing require appropriate nondestructive testing techniques to achieve high processing yield and reliability. This paper p...

Link to pdf: http://rdcu.be/voAK Ongoing trends in microelectronics aim at continuously increasing the integration rate and complexity of microelectronic systems and devices. Novel integration technologies that arise from these demands need to be addressed from a reliability and quality assurance perspective. As a consequence, novel and adapted in...

Tremendous research efforts have been devoted particularly to the development and improvement of through silicon vias (TSV) in order to provide a key enabling technology for vertical system integration. To achieve high processing yield and reliability efficient failure analysis techniques for process control and root cause analysis are required. Th...

Through Silicon Via (TSV) is the most promising technology for vertical interconnection in novel three-dimensional chip architectures. Reliability and quality assessment necessary for process development and manufacturing require appropriate non-destructive testing techniques to detect cracks and delamination defects with sufficient penetration and...

Two different back-end-of-line (BEOL) stacks were indented using Berkovich and wedge tips with different indentation forces to simulate failure modes such as cracks and delamination. The indentation areas were investigated by acoustic GHz-microscopy for the detection of these defects. For validation, results were correlated to the SEM images of FIB...

Gigahertz scanning acoustic microscopy (GHz-SAM) is applied to the characterization of bulk voids in the Cu-Sn material system, often used in micro-connects. An increased demand for the development of miniaturized interconnect technologies, such as micro-connects, means that fast characterization methods are required for the assessment and detectio...

The non-destructive inspection of printed circuit boards (PCBs) represents an issue of constant importance in microelectronics. In this study, the detection of delaminations in modern PCBs by scanning acoustic microscopy (SAM) is described. It is shown that, even though the acoustic analysis is complicated due to the multi-layered build-up, delamin...

This paper discusses the possibility of using Scanning Acoustic Microscopy in GHz frequencies for detection and analysis of stresses around TSVs. An innovative idea was employed to measure the slight variations in Rayleigh wave velocities as a function of Si crystal orientation using a spherical imaging lens. The fringe pattern around an empty TSV...

In the current paper the application of a custom developed 2-dimenional scanning magnetic field microscope based on tunnel-magnetoresistive sensors and subsequent qualitative and quantitative analysis is described. To improve sensitivity and to enable the detection and evaluation of phase deviations, an off-line lock-in approach was employed by dri...

The excitation and propagation of acoustic waves as employed in scanning acoustic microscopy follows highly complex phenomena which commonly cannot be visualized experimentally. The current paper describes the application of modelling and numerical simulation of these phenomena in structures like complex microelectronic samples or acoustic lenses....

The generation and conversion of high power based on electricity has been a highly pursued field of research and engi-neering for many years. The availability of new materials and technologies for generation, handling and conversion of high-power electricity has led to a broadening range of applications. As a consequence the demand on the achievabl...

The current paper presents recent and future developments and trends in scanning acoustic microscopy. It discusses the potential of acoustic microscopy as an in-line applicable and non-destructively operating technique for the application in quality assessment and failure analysis in the field of 3D-integrated microelectronics and wafer bonding. Pa...

This paper discusses the application of two different techniques for failure analysis of Cu through-silicon vias (TSVs), used in 3D stacked-IC technology. The first technique is GHz Scanning Acoustic Microscopy (GHz-SAM), which not only allows detection of delamination, but also the visualization of Rayleigh waves. GHz-SAM can provide information o...

Generation of surface acoustic waves (SAW) on polycrystalline piezoelectric materials is gaining popularity due to possibility of manufacturing ultrathin film of such materials that have diverse applications, e.g. flow separation, particle guiding etc. It can be done by controlling the potential pattern in the electrodes placed on the surfaces of t...

The ultimate aim in the development of concepts, methods and architectures in microelectronic technologies is the continuous reduction of lateral dimensions by increasing integration density, functionality and processing performance of electronic and microelectronic components. Recent trends therefore employ all three spatial dimensions for further...

Application of acoustic GHz-Microscopy (GHz - SAM) in 3D integration technologies for inspecting TSVs. Experimental work has been complemented by modelling and numerical simulation of the wave propagation using PZFlex.

3D-integration is one of the most challenging approaches addressed by researchers in the field of microelectronics in the recent years. With the intension on integrating different components in three dimensions in one device performance and functionality will increase dramatically by reducing the devices footprint. A major challenge in 3D-integrati...

Currently smart cards with integrated silicon dies have found wide application for personal authorization, security identification and payment systems. As a consequence, the complexity of electronics is increasing, thus, specifically adapted failure analysis methods and work flows are required taking the peculiarities of smart card constructions wi...

Metal-based thermocompression bonding enables the creation of hermetic seals formed at relatively low processing temperatures and occupying a small portion of the device area. In the current study we have investigated the application of scanning acoustic microscopy (SAM) for assessing the quality of metal thermocompression bonds, both by evaluating...

Among the technological developments pushed by the emergence of 3D-ICs, Through Silicon Via (TSV) technology has become a standard element in device processing over the past years. As volume increases, defect detection in the overall TSV formation sequence is becoming a major element of focus nowadays. Robust methods for in-line void detection duri...

Current trends in microelectronics focus on three-dimensionally integrating different components to allow for increasing density and functionality of integrated systems. Concepts pursued involve vertical stacking and interconnecting technologies that employ micro bumping, wafer bonding, and through silicon vias (TSVs). Both the increasing complexit...

In this paper the performance of multi-narrow-band spectral analysis was evaluated concerning defect detection in microelectronic components with flip-chip contacts. Today, flip-chip technology is widely applied for interconnecting silicon dies to a substrate within high-end semiconductor packaging technologies. The integrity of the bump solder int...

Among the technological developments pushed by the emergence of 3D-ICs, Through Silicon Via (TSV) technology has become a standard element in device processing over the past years. As volume increases, defect detection in the overall TSV formation sequence is becoming a major element of focus nowadays. Robust methods for in-line void detection duri...

In this paper, a brief summary of potential defect formation and failure characteristics for low temperature plasma-assisted Si wafer bonding in correlation to different influencing factors is given. In terms of a failure catalogue classification, these defects are related to incoming material quality variation, wafer bonding equipment and bonding...

On industrial scale, glass frit bonding is widely used for assembly and encapsulation of MEMS. A key task to guarantee functionality and reliability is the classification of the quality and strength of the bonding interface. Caused by the wide range of used test setups and test parameters, the estimated strength values are not directly comparable t...

New semiconductor chip technologies and technologies for 3D integration require information’s of packaging and interface defects in 3 dimensions, that means the lateral dimension of the defect and the location inside the device or package must be defined. In this paper, new methodical approaches for non destructive failure analysis on 3D integrated...

Glass frit bonding is a widely used encapsulation technology for micro-electro mechanical systems. In order to guarantee functionality and reliability of a bonding seal, qualified test methods are required for evaluating the quality and strength of the bonding interfaces which are considered key parameters. In the presented work adapting the micro-...

Lipid-shelled contrast agents have been the focus of combined experimental and theoretical efforts in order to characterize their dynamics with respect to shell material parameters. The use of independent mechanical measurements such as atomic force microscopy (AFM) for the shell materials has begun to receive attention. Polymer-shelled agents are...

The mechanical properties of cells reflect dynamic changes of cellular organization which occur during physiologic activities like cell movement, cell volume regulation or cell division. Thus the study of cell mechanical properties can yield important information for understanding these physiologic activities. Endothelial cells form the thin inner...

In industrial manufacturing of microelectronic components, non-destructive failure analysis methods are required for either quality control or for providing a rapid fault isolation and defect localization prior to detailed investigations requiring target preparation. Scanning acoustic microscopy (SAM) is a powerful tool enabling the inspection of i...

The increasing demand on the complexity of microelectronic components will soon require architectures that build in the third dimension. A number of current projects and world-wide research in this field focuses on technologies that aim at combining individual devices on wafer level into complex systems that have a variety of features. However, the...

A novel method for non-destructive intramuscular fat (IMF) estimation via spectral ultrasound backscatter analysis of signals obtained from pig carcasses early post mortem is described. A commercial hand-held ultrasound device (center frequency: 2.7 MHz) was modified to focus the sound beam to the longissimus muscle at the 2nd/3rd last rib. Time-re...

Today 3D interconnection approaches are considered to provide one of the most promising enabling technologies for “More than Moore” solutions. In particular, 3D integration can provide significant progress in semiconductor device development regarding increased system functionality and integration density. In this paper, we describe an innovative c...

Young's and shear moduli were analyzed in Eu2+-doped fluorozirconate glasses, which were additionally doped with chlorine ions. Upon annealing between 240 °C and 290 °C, barium chloride nanocrystals were formed in the glass. Determination of the Vickers hardness, H, leads to a slight trend of decreasing hardness for higher annealing temperatures, w...

Due to increasing integration density, breakthrough improvements in the resolution achievable by a specific inspection method are of great interest to the D Integration community. This requirement is particularly driven by wafer bonding technologies that, in addition to mechanical 3D assembly, were also often used to form buried electrical chipto c...

Ultrasound velocity and attenuation of soft tissues have been widely investigated. However, few studies completely covered considerable variations of both, structure and composition. The aim of this study was to collect acoustic reference data of porcine Longissimus muscle and associate them with compositional traits. In addition, measurements were...

Ultrasound is regarded as a promising method to determine the intramuscular fat content of pork loin. At intact carcasses, the signal passes the backfat whose ultrasound parameters (sound velocity and attenuation) have not been fully investigated. This study intended to collect a dataset of ultrasound parameters for individual backfat layers and to...

In industrial manufacturing of microelectronic components, non-destructive failure analysis methods are required for either quality control or for providing a rapid fault isolation and defect localization prior to detailed investigations requiring target preparation. Scanning acoustic microscopy (SAM) is a powerful tool enabling the inspection of i...

Nonuniform residual stresses may develop during anodic bonding due to variations in wafer curvature prior to bonding or due to nanotopography interactions between the bonding surfaces. In this work, we discuss the significance of nonuniform residual stress in anodically bonded wafer pairs and present a method for measuring local stress variations e...

The reduced testability of 3D integrated microelectronic systems poses severe challenges to microstructure diagnostics, fault isolation and failure analysis techniques that are required to detect and analyze electrical opens, high resistive contacts and electrical shorts of the interconnects in the wafer-bonded interface. The potential of applying...

Industrial applications often require failure analysis methods working non-destructively, enabling either a rapid quality control or fault isolation and defect localization prior to a detailed defect investigation requiring target preparation. Scanning acoustic microscopy in the frequency range above 100 MHz provides high axial and lateral resoluti...

The reliability of power electronic devices is significantly related to the material properties of the applied substrates which carry the semiconductor chip and the electric interconnections. The most common solution to fulfill the stringent requirements of these devices, with respect to high isolation voltage, good thermal conductivity, high tempe...

The aim of this study was to estimate the intramuscular fat content (IMF) of porcine longissimus muscle using a handheld ultrasound device with a centre frequency of 3.2 MHz. The IMF estimation method from acoustic parameters obtained by the spectral analysis of ultrasonic echo signal is described. System specific effects and sound propagation effe...

Sound velocity and attenuation of porcine loin muscle, backfat and skin have been investigated. Experiments were performed in vitro at 38°C using a scanning acoustic microscope. With respect to the known anisotropy of muscle, the direction of the incident sound waves relative to the muscle fiber orientation was realized comparable to conditions whe...

The current study aimed on the method development for the estimation of mechanical properties of individual biological cells. Samples investigated ultrasonically were kept under culture conditions and no chemical markers have been applied in order to not alter the cells chemical conditions. For the estimation of mechanical properties namely thickne...

Spectral and wavelet analyses were performed on ultrasound radiofrequency (RF) data collected from centrifuged cell samples containing HEp-2 cells after induction of apoptosis by exposure to camptothecin. Samples were imaged at several time points after drug exposure using high-frequency ultrasound in the range from 10-60 MHz. A 20-MHz transducer w...

Purpose: Currently, no imaging modality is used routinely to assess tumor responses to radiotherapy within hours to days after the delivery of treatment. In this study, we show the application of quantitative ultrasound methods to characterize tumor responses to cancer radiotherapy in vivo, as early as 24 hours after treatment administration. Exper...

For preventing corrosion and for surface protection metallic objects are commonly finished with layers of varnish. The integrity of the varnish and potential defect propagation influence the durability of the metal and hence are a measure of the quality of the finishing. Scanning acoustic microscopy provides high axial and lateral resolution, a suf...

For preventing corrosion and for surface protection metallic objects are commonly finished with layers of varnish. The integrity of the varnish and potential defect propagation influence the durability of the metal and hence are a measure for the quality of the finishing. Scanning acoustic microscopy provides high axial and lateral resolution, a su...

Acoustic tissue properties can be estimated using texture and/or spectral parameter analysis. Spectral analysis is based on the rf-signals whose frequency-content is commonly neglected in conventional B-mode imaging. Attenuation and backscatter values of normal brain tissue were analyzed. Unprocessed rf-data of 20 patients were sampled intraoperati...

The objective of this work is to investigate changes in the acoustic properties of cells when exposed to chemotherapy for monitoring treatment response. High frequency ultrasound spectroscopy (10-60 MHz) and scanning acoustic microscopy (0.9 GHz) were performed on HeLa cells (Ackermann et al. 1954, Masters 2002) that were exposed to the chemotherap...

Intraoperative ultrasound imaging of the brain is used for tumor localization and resection control. The aim of the present study was to prove whether spectral analysis of radio-frequency (rf) signals is able to improve its diagnostic capabilities by adding quantitative acoustical parameters to pure visual analysis. Meningioma was chosen as a first...

Failure analysis in industrial applications often require methods working non-destructively for allowing a variety of tests at a single device. Scanning acoustic microscopy in the frequency range above 100 MHz provides high axial and lateral resolution, a moderate penetration depth and the required non-destructivity. The goal of this work was the d...