Decohesion of Thin Films From Ceramic Substrates

ABSTRACTDecohesion of thin films from ceramic or semiconductor substrates is strongly influenced by internal stresses in films and stress concentrations from edges or flaws as well as by interfacial fracture energy. Residual stresses can cause spontaneous delamination, splitting and curling of films under tension or delamination, buckling and spal ling of films under residual compression, even with good interfacial bonding. Delamination behavior is considered using simple fracture mechanics models, supplemented with preliminary measurements of interfacial fracture energies. Formation conditions largely control internal stresses in films; whereas fracture energies are dictated by interfacial chemistry and mechanical factors such as plasticity.

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Diamond and Diamondlike Composites

10.1115/imece2001/md-24804 ◽

2001 ◽

Author(s):

R. J. Narayan ◽

Q. Wei ◽

J. Sankar ◽

J. Narayan

Keyword(s):

Thin Films ◽

Lattice Mismatch ◽

Composite Films ◽

Substantial Improvement ◽

Internal Stresses ◽

Interatomic Potentials ◽

Wear Properties ◽

Ceramic Substrates ◽

Microelectronic Devices ◽

Biomedical Device

Abstract Diamond, diamond-like, and their composites (with TiC, TiN, and AlN for diamond, and Cu, Ag, Ti, and Si for diamondlike carbon) have extremely desirable chemical, electrical, and mechanical properties. These corrosion- and erosion-resistant coatings have a wide variety of applications, ranging from biomedical device coatings to packaging of microelectronic devices. However, many of these applications are limited by the poor adhesion of these films to metals, ceramics, and polymers. The adhesion of a film is determined primarily by internal stresses in the film, thermal and lattice mismatch, and most importantly by interfacial bonding. We have developed methods based on mechanical interlocking, chemical bonding, grading of interatomic potentials, and the multilayer discontinuous thin films approach to control stresses and strains in thin films. A substantial improvement in adhesion and wear properties is obtained by using these methods selectively. We review issues related to the adhesion of diamond, diamond-like carbon, and composite films on metal, polymeric, and ceramic substrates.

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Microstructural and Electrical Characterization of Barium Strontium Titanatebased Solid Solution Thin Films Deposited on Ceramic Substrates by Pulsed Laser Deposition

MRS Proceedings ◽

10.1557/proc-720-h2.4 ◽

2002 ◽

Vol 720 ◽

Author(s):

Costas G. Fountzoulas ◽

Daniel M. Potrepka ◽

Steven C. Tidrow

Keyword(s):

Thin Films ◽

Dielectric Constant ◽

Pulsed Laser Deposition ◽

Pulsed Laser ◽

Electrical Characterization ◽

Field Variable ◽

Laser Deposition ◽

X Ray Diffraction ◽

Ceramic Substrates ◽

Nominal Thickness

AbstractFerroelectrics are multicomponent materials with a wealth of interesting and useful properties, such as piezoelectricity. The dielectric constant of the BSTO ferroelectrics can be changed by applying an electric field. Variable dielectric constant results in a change in phase velocity in the device allowing it to be tuned in real time for a particular application. The microstructure of the film influences the electronic properties which in turn influences the performance of the film. Ba0.6Sr0.4Ti1-y(A 3+, B5+)yO3 thin films, of nominal thickness of 0.65 μm, were synthesized initially at substrate temperatures of 400°C, and subsequently annealed to 750°C, on LaAlO3 (100) substrates, previously coated with LaSrCoO conductive buffer layer, using the pulsed laser deposition technique. The microstructural and physical characteristics of the postannealed thin films have been studied using x-ray diffraction, scanning electron microscopy, and nano indentation and are reported. Results of capacitance measurements are used to obtain dielectric constant and tunability in the paraelectric (T>Tc) regime.

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Equilibrium Profile of Modern Belted Radial Ply Tires: Its Determination and Performance Benefits

Tire Science and Technology ◽

10.2346/tire.13.410203 ◽

2013 ◽

Vol 41 (2) ◽

pp. 127-151

Author(s):

Rudolf F. Bauer

Keyword(s):

Finite Element ◽

Aspect Ratio ◽

Finite Element Methods ◽

Mathematical Analysis ◽

Internal Stresses ◽

Stress Concentrations ◽

Equilibrium Profiles ◽

Equilibrium Profile ◽

And Performance ◽

Beneficial Property

ABSTRACT The benefits of a tire's equilibrium profile have been suggested by several authors in the published literature, and mathematical procedures were developed that represented well the behavior of bias ply tires. However, for modern belted radial ply tires, and particularly those with a lower aspect ratio, the tire constructions are much more complicated and pose new problems for a mathematical analysis. Solutions to these problems are presented in this paper, and for a modern radial touring tire the equilibrium profile was calculated together with the mold profile to produce such tires. Some construction modifications were then applied to these tires to render their profiles “nonequilibrium.” Finite element methods were used to analyze for stress concentrations and deformations within all tires that did or did not conform to equilibrium profiles. Finally, tires were built and tested to verify the predictions of these analyses. From the analysis of internal stresses and deformations on inflation and loading and from the actual tire tests, the superior durability of tires with an equilibrium profile was established, and hence it is concluded that an equilibrium profile is a beneficial property of modern belted radial ply tires.

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Thermally Induced Delamination Buckling of a Thin Metal Layer on a Ceramic Substrate

Journal of Electronic Packaging ◽

10.1115/1.1604152 ◽

2003 ◽

Vol 125 (4) ◽

pp. 512-519 ◽

Cited By ~ 3

Author(s):

C. J. Liu ◽

L. J. Ernst ◽

G. Wisse ◽

G. Q. Zhang ◽

M. Vervoort

Keyword(s):

Failure Modes ◽

Research Effort ◽

Metal Layer ◽

Electronic Packages ◽

Ceramic Substrates ◽

Thermally Induced ◽

Thermal Expansion Coefficients ◽

Interface Delamination ◽

Delamination Buckling ◽

Expansion Coefficients

Interface delamination failure caused by thermomechanical loading and mismatch of thermal expansion coefficients and other material properties is one of the important failure modes occurring in electronic packages, thus a threat for package reliability. To solve this problem, both academic institutions and industry have been spending tremendous research effort in order to understand the inherent failure mechanisms and to develop advanced and reliable experimental and simulation methodologies, thus to be able to predict and to avoid interface delamination before physical prototyping. Various damage mechanisms can be involved and can result in interface delamination phenomena. These are not all sufficiently addressed and/or reported so far, probably because of the complexities caused by the occurrence of strong geometric and materials nonlinearities. One of the phenomena being insufficiently understood so far is the so-called buckling-driven delamination of thin metalic layers on ceramic substrates. This phenomenon will be discussed in the present paper.

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Amorphous alumina thin films deposited on titanium: Interfacial chemistry and thermal oxidation barrier properties

physica status solidi (a) ◽

10.1002/pssa.201532838 ◽

2015 ◽

Vol 213 (2) ◽

pp. 470-480 ◽

Cited By ~ 6

Author(s):

Loïc Baggetto ◽

Cédric Charvillat ◽

Yannick Thébault ◽

Jérôme Esvan ◽

Marie-Christine Lafont ◽

...

Keyword(s):

Thin Films ◽

Thermal Oxidation ◽

Barrier Properties ◽

Interfacial Chemistry ◽

Amorphous Alumina

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A Computational Model to Assess Poststenting Wall Stresses Dependence on Plaque Structure and Stenosis Severity in Coronary Artery

Mathematical Problems in Engineering ◽

10.1155/2014/937039 ◽

2014 ◽

Vol 2014 ◽

pp. 1-12

Author(s):

Zuned Hajiali ◽

Mahsa Dabagh ◽

Payman Jalali

Keyword(s):

Coronary Arteries ◽

Computational Models ◽

Strong Dependence ◽

Internal Stresses ◽

Shear Stresses ◽

Stress Concentrations ◽

Opening Pressure ◽

Fibrous Cap ◽

Stent Restenosis ◽

Von Mises

The current study presents computational models to investigate the poststenting hemodynamic stresses and internal stresses over/within the diseased walls of coronary arteries which are in different states of atherosclerotic plaque. The finite element method is applied to build the axisymmetric models which include the plaque, arterial wall, and stent struts. The study takes into account the mechanical effects of the opening pressure and its association with the plaque severity and the morphology. The wall shear stresses and the von Mises stresses within the stented coronary arteries show their strong dependence on the plaque structure, particularly the fibrous cap thickness. Higher stresses occur in severely stenosed coronaries with a thinner fibrous cap. Large stress concentrations around the stent struts cause injury or damage to the vessel wall which is linked to the mechanism of restenosis. The in-stent restenosis rate is also highly dependent on the opening pressure, to the extent that stenosed artery is expanded, and geometry of the stent struts. The present study demonstrates, for the first time, that the restenosis is to be viewed as a consequence of biomechanical design of a stent repeating unit, the opening pressure, and the severity and morphology of the plaque.

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Mechanical Modeling of Thin Films and Cover Plates Bonded to Graded Substrates

Journal of Applied Mechanics ◽

10.1115/1.2936237 ◽

2008 ◽

Vol 75 (5) ◽

Cited By ~ 18

Author(s):

Mehmet A. Guler

Keyword(s):

Thin Films ◽

Stress Intensity ◽

Interfacial Shear Stress ◽

Contact Problems ◽

Stress Concentrations ◽

Elastic Continuum ◽

Temperature Changes ◽

Initiation And Propagation ◽

Axial Normal Stress ◽

Cover Plates

In this study, the contact problems of thin films and cover plates are considered. In these problems, the loading consists of any one or combination of stresses caused by uniform temperature changes and temperature excursions, far field mechanical loading, and residual stresses resulting from film processing or welding. The primary interest in this study is in examining stress concentrations or singularities near the film ends for the purpose of addressing the question of crack initiation and propagation in the substrate or along the interface. The underlying contact mechanics problem is formulated by assuming that the film is a “membrane” and the substrate a graded elastic continuum, and is solved analytically by reducing it to an integral equation. The calculated results are the interfacial shear stress between the film and the graded substrate, the Mode II stress intensity factor at the end of the film, and the axial normal stress in the film. The results indicate that grading the material properties of the substrate helps to decrease the film stresses and the stress intensity factors at the free edges and to lower the axial normal stresses at the midsection where the film is most likely to crack.

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Elastic Properties of Sputtered Thin Films: Influence of Different Preparation Conditions

MRS Proceedings ◽

10.1557/proc-308-95 ◽

1993 ◽

Vol 308 ◽

Cited By ~ 1

Author(s):

C.E. Bottani ◽

M. Elena ◽

M. Beghi ◽

G. Ghislotti ◽

L. Guzman ◽

...

Keyword(s):

Thin Films ◽

Light Scattering ◽

Hard Coatings ◽

Elastic Behaviour ◽

Internal Stresses ◽

Pvd Coatings ◽

Tin Films ◽

Si Substrates ◽

Preparation Conditions ◽

First Results

ABSTRACTThis work presents the first results of a study aimed at better understanding the elastic behaviour of hard coatings produced by various techniques. This is important also in view of the need to be able to control the level of internal stresses, particularly in PVD coatings. It is well known that in extreme cases excessive internal stress can lead to complete film destruction. We devote this paper to reactively magnetron sputtered TiN, one of the most widely used compounds. Thin TiN films of different compositions were deposited on Si substrates and characterized by SEM, AES, XRD and Brillouin light scattering.

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