Fraunhofer-Institut für Zuverlässigkeit und Mikrointegration IZM

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  • Publication
    Characterisation of Cu/Cu bonding using self-assembled monolayer
    ( 2018)
    Lykova, M.
    ;
    Panchenko, I.
    ;
    Künzelmann, U.
    ;
    Reif, J.
    ;
    Geidel, M.
    ;
    Wolf, M.J.
    ;
    Lang, K.-D.
    Purpose: Cu/Cu diffusion bonding is characterised by high electrical and thermal conductivity, as well as the mechanical strength of the interconnects. But despite a number of advantages, Cu oxidises readily upon exposure to air. To break through the adsorbed oxide-layer high temperature and pressure, long bonding time and inert gas atmosphere are required during the bonding process. This paper aims to present the implementation of an organic self-assembled monolayer (SAM) as a temporary protective coating that inhibits Cu oxidation. Design/methodology/approach: Information concerning elemental composition of the Cu surface has been yielded by X-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared (FTIR) spectroscopy. Two types of substrates (electroplated and sputtered Cu) are prepared for thermocompression bonding in two different ways. In the first case, Cu is cleaned with dilute sulphuric acid to remove native copper oxide. In the second case, passivation with SAM followed the cleaning step with dilute sulphuric acid. Shear strength, fracture surface, microstructure of the received Cu/Cu interconnects are investigated after the bonding procedure. Findings: The XPS method revealed that SAM can retard Cu from oxidation on air for at least 12 h. SAM passivation on the substrates with sputtered Cu appears to have better quality than on the electroplated ones. This derives from the results of the shear strength tests and scanning electron microscopy (SEM) imaging of Cu/Cu interconnects cross sections. SAM passivation improved the bonding quality of the interconnects with sputtered Cu in comparison to the cleaned samples without passivation. Originality/value: The Cu/Cu bonding procedure was optimised by a novel preparation method using SAMs which enables storage and bonding of Si-dies with Cu microbumps at air conditions while remaining a good-quality interconnect. The passivation revealed to be advantageous for the smooth surfaces. SEM and shear strength tests showed improved bonding quality for the passivated bottom dies with sputtered Cu in comparison to the samples without SAM.
  • Publication
    Anwendungen hydrophober Oberflächenmodifikationen in der Mikrosystemtechnik
    ( 2013)
    Georgi, L. von
    ;
    Kahle, R.
    ;
    Lang, K.-D.
    ;
    Bauer, J.
    ;
    Braun, T.
    ;
    Becker, K.-F.
    ;
    Jung, E.
    In this report, the principles and processes involved in surface modification to create hydrophobic/ hydrophilic surfaces for use in microsystems are set out. Two examples are used to illustrate this, the first being contactless placing of small microelectronic components and the second being the manipulation of reagent-containing water droplets for rapid micro-diagnosis.
  • Publication
    Generative Fertigungstechnologien für eine Direktintegration von mikroelektronischen Komponenten und Kontaktstrukturen
    ( 2013)
    Ifland, D.
    ;
    Ansorge, F.
    ;
    Baar, C.
    ;
    Lang, K.-D.
    The present article deals with the development ofSys-tem-in-Package (SiP) modules, which are produced by stereolithography, an additive fabrication process. During the production process of the SIP module the necessary electrical components will be integrated into the carrier substrate. Afterwards the components will be interconnected of an electrically conductive adhesive. This method is intended to demonstrate a novel three-dimensional construction and connection technology for microsystems.