Fraunhofer-Institut für Zuverlässigkeit und Mikrointegration IZM

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  • Publication
    Prepolymer film growth by adsorption out of solution on silicon and aluminium. An atomic force microscope study
    ( 1995)
    Gesang, T.
    ;
    Höper, R.
    ;
    Dieckhoff, S.
    ;
    Hartwig, A.
    ;
    Possart, W.
    ;
    Hennemann, O.-D.
    A cyanurate prepolymer was applied to smooth silicon wafers or to distinctly structured aluminum coatings. The surface composition of the substrates was investigated by X-ray Photoelectron Spectroscopy (XPS), Auger Electron Spectroscopy (AES) and Ellipsometry. The application methods, spin coating and dip coating represent adsorption by a technical process exerting significant shear stresses or nearly equilibrated conditions, respectively. The mean thickness of the prepolymer film was adjusted by variation of the concentration of the solution and checked by ellipsometry. Atomic Force Microscopy (AFM) monitored the development of the respective film morphologies of all 4 systems (silicon / aluminum, spin / dip coating) in the mean film thickness range from 1 to 50 nm.
  • Publication
    Quantitative Erfassung von Oberflächentopographien
    ( 1995)
    Gesang, T.
    ;
    Höper, R.
    ;
    Possart, W.
    ;
    Hennemann, O.-D.
    Some applications of Atomic Force Microscopy in adhesion science and technology are presented. The essential advantage of AFM over mere imaging methods is the capability of quantitatively acquiring the topography of the sample surface. This in turn allows a number of useful quantitative evaluations of the surface. The examples described are fluorination and oxygen plasma treatment of a polypropylene foil for improvement of adhesion. Moreover it is evidenced that AFM can provide nanoscopic insight into adhesion phenomena by imaging the islands of adsorbed adhesive molecules. They show specific characteristics of their geometric shape depending on the kind of adhesive molecule and on the type of substrate.
  • Publication
    XPS studies of thin polycyanurate films on silicon wafers and aluminium substrates
    ( 1995)
    Dieckhoff, S.
    ;
    Schlett, V.
    ;
    Possart, W.
    ;
    Hennemann, O.-D.
    The fundamental understanding of the chemical and physical phenomena of the adhesion at substrate/polymer interfaces is of great importance in order to be able to solve and control adhesion problems. We used a prepolymer of the diandicyante of bisphenol A (DCBA) as a model of a network polymer. The adsorption of thin DCBA-prepolymer films on silicon and aluminium substrates is studied by x-ray photoelectron spectroscopy (XPS), infrared spectrscopy (IR) and ellipsometry.
  • Publication
    Organic film formation investigated by atomic force microscopy on the nanometer scale
    ( 1995)
    Gesang, T.
    ;
    Höper, R.
    ;
    Dieckhoff, S.
    ;
    Schlett, V.
    ;
    Possart, W.
    ;
    Hennemann, O.-D.
  • Publication
    AFM investigations of the initial stages of prepolymer film growth on aluminium
    ( 1995)
    Gesang, T.
    ;
    Höper, R.
    ;
    Dieckhoff, S.
    ;
    Fanter, D.
    ;
    Hartwig, A.
    ;
    Possart, W.
    ;
    Hennemann, O.-D.
    A cyanurate prepolymer was applied to aluminium coated silicon wafers by adsorption out of solution. Film growth from the initial stages to closed films was studied by Atomic Force Microscopy (AFM). Sample preparation in the presence of external forces (spin coating) leads to film morphologies very different from adsorption near equilibrium (dip coating). The edge of the non closed films can be characterized by means of a borderline angle. The influence of specific prepolymer - substrate interactions, external forces and substrate topography is discussed. The formation of ultrathin, amorphous organic films on solids is studied for an application oriented model system. A prepolymer or a copolymer of a cyanate based high temperature adhesive is spin cast or dip coated onto silicon wafers or aluminium coatings to produce films as thin as possible. The mean thickness ranges from 1 - 4 nm. After a thorough substrate characterization by imaging and spectroscopic methods, the various films we re investigated by atomic force microscopy. Besides imaging, for discontinuous films atomic force microscopy was also utilized to measure the 'borderline angle' introduced in this paper. The borderline angle characterizes the slope of the surface of an isolated adsorbed organic object near the substrate. Thus, it is the geometric equivalent to the classical contact angle of a lying liquid drop. However, the phenomena leading to these angles are different. Nevertheless, the borderline angle is related to the affinity of the organic phase to the substrate an d thus will play an important role in future investigations of film formation and adhesion on the nanometer scale.
  • Publication
    AFM - Abbildung feinster Strukturen
    ( 1995)
    Gesang, T.
    ;
    Höper, R.
    ;
    Possart, W.
    ;
    Hennemann, O.-D.
    Atomic Force Microscopy allows novel investigations into birth and growth of ultrathin polymeric films. This bears relevance both for coatings and for adhesive bonding technology. The article describes the initial stages of prepolymeric film growth on silicon wafers and aluminum evaporation layers which have been selected for their application orientation. The prepolymer chosen is based on the dicyanate of bisphenole A and is a potential ingredient for high temperature adhesives. The initial stages of film growth have been accomplished by adsorption out of solution. The application techniques either realize adsorption with significant centrifugal forces ("Spin Coating`) or in nearly equilibrated condition ("Dip-Coating"). The investigations reveal the respective kind of growth which highly depends on the type of substrate and on the application technique.
  • Publication
    Adsorption behaviour of a prepolymer on aluminium and silicon.
    ( 1994)
    Hartwig, A.
    ;
    Zha, Z.
    ;
    Possart, W.
    ;
    Hennemann, O.-D.
    The preparation of thin layers of a prepolymer containing cyanate and triazine groups by dip-coating is described. The substrates are silicon and aluminium covered with their native oxide layer. The influence of immersion time, concentration, temperature and dip-speed on the thickness of the layer formed on the substrate was examined.
  • Publication
    Adsorption and growth of polycyanurate films on silicon wafers and aluminium substrates
    ( 1994)
    Dieckhoff, S.
    ;
    Schlett, V.
    ;
    Possart, W.
    ;
    Hennemann, O.-D.
    We have investigated thin films of a DCBA prepolymer on Si and Al substrates. High-resolution Cls, Ols and Nls x-ray photoelectron spectra reveal some thickness-dependent features, which lead to an adsorption model for the DCBA prepolymer molecules. The adsorption of the first layer is governed by the interaction of the triazine rings with the substrate interface.