Now showing 1 - 10 of 4511
  • Publication
    Laboratory X-ray Microscopy of 3D Nanostructures in the Hard X-ray Regime Enabled by a Combination of Multilayer X-ray Optics
    ( 2024)
    Lechowski, Bartlomiej
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    Kutukova, Kristina
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    Grenzer, Jörg
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    Panchenko, Juliana
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    Krüger, Peter
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    ;
    Zschech, Ehrenfried
    High-resolution imaging of buried metal interconnect structures in advanced microelectronic products with full-field X-ray microscopy is demonstrated in the hard X-ray regime, i.e., at photon energies > 10 keV. The combination of two multilayer optics—a side-by-side Montel (or nested Kirkpatrick–Baez) condenser optic and a high aspect-ratio multilayer Laue lens—results in an asymmetric optical path in the transmission X-ray microscope. This optics arrangement allows the imaging of 3D nanostructures in opaque objects at a photon energy of 24.2 keV (In-Kα X-ray line). Using a Siemens star test pattern with a minimal feature size of 150 nm, it was proven that features < 150 nm can be resolved. In-Kα radiation is generated from a Ga-In alloy target using a laboratory X-ray source that employs the liquid-metal-jet technology. Since the penetration depth of X-rays into the samples is significantly larger compared to 8 keV photons used in state-of-the-art laboratory X-ray microscopes (Cu-Kα radiation), 3D-nanopattered materials and structures can be imaged nondestructively in mm to cm thick samples. This means that destructive de-processing, thinning or cross-sectioning of the samples are not needed for the visualization of interconnect structures in microelectronic products manufactured using advanced packaging technologies. The application of laboratory transmission X-ray microscopy in the hard X-ray regime is demonstrated for Cu/Cu6Sn5/Cu microbump interconnects fabricated using solid–liquid interdiffusion (SLID) bonding.
  • Publication
    Forced Motion Activated Self-Alignment of Micro-CPV Solar Cells
    In micro-concentrating photovoltaics (micro-CPV), the size of solar cells is reduced (<1x1 mm 2 ) compared to conventional CPV. However, the quantity and requirement for placement accuracy of solar cells is increased. To be economically competitive, a promising possibility for the die assembly is a high throughput and relatively unprecise pick and place process combined with surface tension-driven self-alignment of the liquid solder. In this article, this approach is experimentally investigated, with a focus on the influences of solder volume, receiving pad layouts, and initial displacements of the cells on the self-alignment accuracy. Here, we show that an induced motion due to the initial displacement of the cells or due to solder flow along tracks leads to a more robust and accurate process. We found that less solder and rather smaller pads than cells (here by 92 μm or 10.4% of the cell length) are beneficial for self-alignment accuracy. However, for micro-CPV, conductor tracks connected to the pad are required for electrical interconnection and heat dissipation. Here, all cells are self-aligned and reach an accuracy between -15 and +15 μm, which is mainly due to the cell-to-pad size difference. Optical simulations show that this displacement would lead to an optical loss of 0.1% abs instead of 12.1% abs when displacing the cell by 150 μm. Thus, the self-alignment using the surface tension of the liquid solder leads to sufficient accuracy.
  • Publication
    Sensor Systems for Extremely Harsh Environments
    Sensors are key elements for capturing environmental properties and are today indispensable in the industry for monitoring and control of industrial processes. Many applications are demanding for highly integrated intelligent sensors to meet the requirements on safety, clean and energy efficient operation or to gain process information in the context of industry 4.0. While in many everyday objects highly integrated sensor systems are already state of the art, the situation in an industrial environment is clearly different. Frequently the use of sensor systems is impossible, due to the fact that the extreme ambient conditions of industrial processes like high operating temperatures or strong mechanical loads do not allow a reliable operation of sensitive electronic components. Eight Fraunhofer Institutes have bundled their competencies and have run the Fraunhofer Lighthouse Project ‘eHarsh’ to overcome this situation. The project goal was to realize sensor systems for extremely harsh environments, whereby sensor systems are not only pure sensor elements, rather containing one or multiple sensor elements and integrated readout electronics. Various technologies which are necessary for the realization of such sensor systems have been identified, developed and finally bundled in a technology platform. These technologies are e. g. MEMS and ceramic based sensors, SOI-CMOS based integrated electronics, board assembly and laser based joining technologies. All these developments have been accompanied by comprehensive tests, material characterization and reliability simulations. Based on the platform a pressure sensor for turbine applications has been realized to prove the performance of the eHarsh technology platform.
  • Publication
    Wafer Level Capping Technology for Vacuum Packaging of Microbolometers
    ( 2023-08-03) ; ; ;
    Meier, Dirk
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    Malik, Nishant
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    ; ;
    Roy, Avisek
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    Nguyen, Hoang-Vu
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    Nguyen, Thanh-Phuc
    This paper presents novel technology developments for vacuum wafer level packaging of microbolometer arrays for thermal infrared sensors targeting applications in automotive, safety, and security/surveillance. The concept is based on fabrication of large cap structures on temporary carrier wafers and their subsequent transfer bonding to device wafers. The objective of the presented work was to develop and test wafer level vacuum packaging for MEMS microbolometer arrays (MBA) fabricated on read out integrated circuit (ROIC) wafers. For that, related MBA layouts integrating diverse Pirani vacuum test structures were fabricated on 200-mm silicon wafers. With intent of hermeticity, all wafer bonding steps were done by AuSn soldering using seal rings, which were deposited by electroplating. The relevant process flows with alternative process options as well as the obtained results of the capping approaches are presented and discussed extensively in this article. For characterization of the sealing results, Pirani test structures were utilized. First, their resistance vs. pressure behavior was determined under controlled reference vacuum. The measured resistance values of identical structures after capping were then compared with the reference data to estimate the residual vacuum inside the cavity of the bonded cap structures.
  • Patent
    Folienkondensator mit integriertem Wärmeableitelement und Verfahren für dessen Herstellung
    ( 2023-07-27) ;
    Seidenstücker, Dominik
    ;
    Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V.
    Es wird ein Folienkondensator (10) vorgeschlagen, der wenigstens ein erstes Kondensatormodul (2) und ein zweites Kondensatormodul (2), die jeweils eine alternierende Abfolge von dielektrischen Kunststoffschichten (3) und elektrisch leitfähigen Metallschichten (4) umfassen und wenigstens einen ersten nach außen geführten elektrischen Anschluss (6) und wenigstens einen zweiten nach außen geführten elektrischen Anschluss (6), wobei jeder der Anschlüsse (6) mit dem ersten und mit dem zweiten Kondensatormodul (2) elektrisch leitend verbunden ist, aufweist. Weiterhin umfasst der Folienkondensator wenigstens ein erstes Wärmeableitelement (12), das zwischen dem ersten und zweiten Kondensatormodul (2) angeordnet ist und das entweder mit dem ersten oder mit dem zweiten elektrischen Anschluss (6) elektrisch leitfähig und thermisch leitfähig verbunden ist, so dass Wärme der Kondensatormodule (2), die von dem Wärmeableitelement (12) aufgenommen wird, über den entsprechend verbundenen Anschluss (6) nach außen führbar ist.
  • Publication
    Use of Rotary Ultrasonic Plastic Welding as a Continuous Interconnection Technology for Large-Area e-Textiles
    ( 2023-01-28) ;
    Hohner, Sebastian
    ;
    For textile-based electronic systems with multiple contacts distributed over a large area, it is very complex to create reliable electrical and mechanical interconnections. In this work, we report for the first time on the use of rotating ultrasonic polymer welding for the continuous integration and interconnection of highly conductive ribbons with textile-integrated conductive tracks. For this purpose, the conductive ribbons are prelaminated on the bottom side with a thermoplastic film, which serves as an adhesion agent to the textile carrier, and another thermoplastic film is laminated on the top side, which serves as an electrical insulation layer. Experimental tests are used to investigate the optimum welding process parameters for each material combination. The interconnects are initially electrically measured and then tested by thermal cycling, moisture aging, buckling and washing tests, followed by electrical and optical analyses. The interconnects obtained are very low ohmic across the materials tested, with resulting contact resistances between 1 and 5 mOhm. Material-dependent results were observed in the reliability tests, with climatic and mechanical tests performing better than the wash tests for all materials. In addition, the development of a heated functional prototype demonstrates a first industrial application.
  • Publication
    Investigation of failure mechanism of aluminum-scandium wire bond contact under active power cycle test
    ( 2023)
    Yamaguchi, Tadashi
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    Suto, Yuya
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    Araki, Noritoshi
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    Eto, Motoki
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    Groth, Anne
    The failure mechanism of aluminum-scandium (Al-Sc) wire bond in comparison with pure Al wire bond under active power cycle (APC) test was investigated. To monitor the degradation of the bond quality, bond shear forces (shear force) were measured over the testing cycles at different level of temperature swing (ΔT). The results show that the Al-Sc wire bond was much more robust than the pure Al wire bond when the ΔT (Tmax) was mild. On the other hand, as the ΔT was increased, the shear force reduction in the Al-Sc wire bond became more and more remarkable. In the cross-sectional analysis of bond contact after the APC tests, a significant crack propagation was observed even for low ΔT conditions for the pure Al wire, and the crack progressed primarily on the wire side of the bond area. As for the Al-Sc wire, while the bond crack was efficiently suppressed for low ΔT conditions, a significant progress of crack was observed at high ΔT conditions, and the crack grew mainly through the Al pad side of the bond area. A detailed analysis at the bond interface after the APC test at high ΔT condition revealed three phenomena at the Al pad side of the bond area: grain coarsening, precipitation of Cu particles, and large void formation. As the material strength is compromised by these effects, the crack grew more easily through the Al pad side of the contact area, resulting in a rapid reduction of shear force at high ΔT. The bond failure mechanism obtained in this study will provide a valuable insight for the future development of high reliability power semiconductor device.
  • Publication
    6 Core fiber and VCSEL based interferometer sensor for motion or vibration monitoring
    ( 2023)
    Chorchos, Łukasz
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    Szostkiewicz, Łukasz
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    Ledentsov, Nikolay N.
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    Turkiewicz, Jarosław P.
    We demonstrate a XYZ motion / vibration sensor based on a 6-core fiber interferometer and a VCSEL lasers array. The sensor can detect changes in movement as low as 500 um and frequencies ranging from 1 Hz to 100 kHz with potential to extend this range further.
  • Publication
    Determination of Lemaitre Damage Parameters for Al H11 Wire Material
    ( 2023)
    Kuttler, Simon
    ;
    Abali, Bilen Emek
    ;
    The quality of wirebond interconnects is characterized by shear and pull tests. For such a simulation we need an adequate damage model, since a purely elasto-plastic model fails to give the full picture [1]. For the description of damage, the Lemaitre damage model is selected, because this model is already used in comparable blanking simulations [2]. In addition, the main damage-driving factor of this damage model is the equivalent plastic strain, which is known to be the suitable failure criteria for ductile materials. The model, introduced by Lemaitre in 1985, is for isotropic ductile damage [3]. It has been used and extended in many other works. Still, more than three decades later, modelling free evolving multiaxial damage is often a more scientific topic and has not yet been proven a sufficient engineering tool to investigate destructive tests by numerical simulation. Reducing the amount of tests has been and still is a demand to save time in the design process. Therefore, it is needed to further investigate the capabilities of such damage models on complex applications. Indeed, the damage parameters first need and will be determined in this study for the material used in the application.
  • Publication
    A Closer Look to Fan-out Panel Level Packaging
    ( 2023) ;
    Hölck, Ole
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    Voitel, Marcus
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    Obst, Mattis
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    ; ; ;
    Schneider-Ramelow, Martin
    Fan-out Wafer and Panel Level Packaging are two of the dominating trends in microelectronics packaging. Both approaches with different flavors as RDL last face-up or face-down have reached maturity and are introduced in high volume manufacturing. This paper discusses warpage in detail as one key challenge in fan-out packaging and how to influence the warpage during processing of a reconfigured panel for Chip first / RDL last approach.