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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 72 (1992), S. 1821-1832 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Electrical resistance of Al-1 wt % Si thin-film conductors has been measured as a function of time t, temperature, and current polarity in order to investigate both generation and recovery of (microstructural) damage caused by electromigration. The fractional change of electrical resistance ΔR/R is characterized by three distinct stages: (i) undetectable ΔR/R during an incubation period τ; (ii) linear increase of ΔR/R with t−τ; and (iii) abrupt decrease of ΔR/R when polarity is reversed, followed by gradual resumption of the previous linear increase. Examination of the conductor surface during these three stages by scanning electron microscopy reveals: (i) undetectable microstructural damage; (ii) generation of (first) holes and (then) hillocks; and (iii) recovery followed by further generation of microstructural damage. Results are interpreted by (i) generation of stress σ in grain boundaries; (ii) formation of holes when σ exceeds a critical tensile stress σ+c and hillocks when σ exceeds a critical compressive stress σ−c (||σ+c|| 〈 ||σ−c||), and (iii) interchange of tensile and compressive stress by polarity reversal. The last stage, in fact, represents superposition of a continuation of the linear increase (degradation) of ΔR/R due to the applied current and an exponential decrease (healing) of ΔR/R, characterized by τ, due to stress relaxation. In general, damage and subsequent healing by electromigration involve a delicate balance between applied current, time, and spatial distribution of (elastic) tensile and compressive stress, (anelastic) formation of holes, and (plastic) formation of hillocks, as dictated by the concomitant microstructure.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Materials Research 6 (1976), S. 361-387 
    ISSN: 0084-6600
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 78 (1995), S. 3833-3838 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Groove profiles are computed under isotropic conditions for the intersection of a periodic array of grain boundaries with an external surface, assuming that grain boundary flux I is directed to (I(approximately-greater-than)0) or away from (I〈0) the surface. When I=0, the surface assumes an equilibrium (time-independent) profile. For I≠0, in a range bounded by upper and lower limits that depend on geometry and material parameters, a global steady-state develops in which the entire surface advances (I(approximately-greater-than)0) or recedes (I〈0) from its original position at constant velocity. Beyond these limits, the surface near the groove roots becomes diffusively detached from the remaining surface. A rapidly growing ridge (I(approximately-greater-than)0) or slit (I〈0) then develops along each grain boundary, whose tip ultimately translates at constant velocity in a local steady state, leaving the remaining surface behind. These velocity regimes govern the ultimate stability of polycrystalline materials subjected to large electric (electromigration) or stress (creep) fields, especially in thin films where grain size approximates film thickness. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 80 (1996), S. 6670-6676 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Advancement of a fine slit along a planar grain boundary in an electric field E0, applied parallel to the slit, is investigated by considering electromigration along both the grain boundary and the slit surface. Electrically induced flux in the grain boundary Igb (+ toward the slit tip) and both electrically and curvature-induced fluxes on the slit surfaces are considered assuming 2Is〉Igb, where Is is the flux (+ away from the slit tip) on each of the parallel slit surfaces far removed from the tip. Steady-state solutions of the transport equations are classified according to the value of a parameter β=tan−1 (2Is/Igb) which, under reasonable assumptions, depends on material parameters only. For 5π/4≥β≥β2, unique steady-state solutions exist; for β2〉β〉β1, multiple steady-state solutions occur; below β1≥π/4, no steady-state solution is possible. Since β1〈π/2, Igb〉0 (flux exiting the grain boundary into the slit) for all cases in which no steady-state solution is possible. In the case of multiple solutions, those corresponding to smallest width (and hence largest velocity) are determined. For all steady-state solutions, slit width and tip velocity scale as E−1/20 and E3/20, respectively. Results also apply to the propagation of a slit within a grain or along a passivation layer. Generally, tip velocities can approach 1 nm/s (3.6 μm/h), thereby representing a likely failure mechanism in fine-line (near bamboo structure) interconnects. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 64 (1988), S. 5428-5430 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Mono- and polycrystalline Ni films, ranging in thickness from 19 to 382 nm, have been produced by vacuum deposition on (001) monocrystalline Ag/NaCl and on glass substrates, respectively. Subsequently, saturation magnetization Ms, magnetogyric factor γ/2π, and effective uniaxial anisotropy Hk were measured by a combination of vibrating sample magnetometer and ferromagnetic resonance (FMR), and corresponding internal stress σ was measured by a levered optical beam reflection technique. In addition, the microstructure of both mono- and polycrystalline films has been characterized by conventional and cross-section transmission electron microscopy. Saturation magnetization can be interpreted by the presence of a magnetic dead layer of about 9 nm and a constant value of 434 emu/cm3, thereafter. Results from FMR can be described by contributions from shape and stress-induced anisotropy. Corresponding values of σ, as computed from Hk, are in satisfactory agreement with values measured by the optical beam reflection technique and yield values of about 1010 dyn/cm2; σ generally decreases with increasing film thickness and annealing time and temperature. Finally, monocrystalline films are characterized by a single FMR peak; polycrystalline films thicker than about 200 nm are characterized by multiple peaks. Occurrence of these multiple peaks is attributed to variation in the effective magnetoelastic constant as a result of a change from equiaxed to columnar grain morphology.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 57 (1985), S. 2155-2160 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Amorphization produced by ion implantation and subsequent crystallization produced by thermal processing have been investigated in films of (SmYGdTm)3Ga0.4Fe4.6O12 garnet by transmission electron microscopy, incorporating a special cross-sectioning technique. These films were produced by liquid-phase epitaxy on {111} garnet substrates and subsequently implanted with ions of deuterium at 60 keV and doses ranging from 0.50 to 4.5×1016 D+2/cm2 and ions of oxygen at 110 keV and doses ranging from 0.95 to 8.6×1014 O+/cm2. The amorphization process evolves in four separate stages: (1) an implanted (crystalline) band, delineated by the implantion strain profile, forms at doses of about 0.50×1016 D+2/cm2/ and 0.95 O+/cm2, (2) isolated amorphous regions of about 10 nm in diameter form at doses of about 1.0×1016 D+2/cm2 and 1.9×1014 O+/cm2, (3) the amorphous regions merge to form a continuous band below the implanted surface at doses of about 3.0×1016 D+2/cm2 and 5.7×1014 O+/cm2, and (4) this band expands to the implanted surface at larger doses. Amorphization is caused by implantation with oxygen, but prior implantation with deuterium sensitizes the lattice by increasing the strain. The crystallization process evolves in three separate stages: (1) small crystallites, about 10 nm in size, form throughout the entire amorphous band after annealing for 10 min at 350 °C, (2) larger crystallites nucleate and grow from the implanted surface and amorphous/crystalline interface after annealing for 10 min at 450 °C, and (3) these crystallites grow in size until they merge to form a continuous polycrystalline layer. Some epitaxial regrowth of the monocrystalline into the amorphous region is also observed. Details of these processes are interpreted in terms of atomic displacement mechanisms and compared with corresponding changes of certain magnetic properties.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 61 (1987), S. 3804-3806 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Thin films of cobalt, nickel, and their alloys have been produced on glass substrates by thermal evaporation at oblique angles of incidence α, measured with respect to the substrate normal, ranging from 20° to 78°. Resultant films are characterized by a columnar grain structure inclined toward the source by an angle β, also measured with respect to the substrate normal, such that 2 tan β∼tan α. For α〉60°, the columnar grains assume a rodlike morphology surrounded by voids, whereas for α〈60°, these grains assume a platelike morphology, also inclined toward the source and separated by voids. The void size, defined by spacing between adjacent rods or plates, increases with increasing values of α. Moreover, for α〉60°, the easy axis of magnetization is oriented in the vapor plane, defined by the plane parallel to both the direction of incident flux and substrate normal, whereas, for α〈60°, this axis is oriented perpendicular to the vapor plane. Accordingly, the easy axis of magnetization is oriented parallel to the rodlike morphology when α〉60°, and parallel to the platelike morphology (and in the plane of the film), when α〈60°. Finally, magnetic coercivity increases rapidly at the critical angle of 60°, as transition from platelike to rodlike morphology occurs.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 59 (1986), S. 1147-1155 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Mechanisms of interdiffusion in copper/nickel thin-film couples have been investigated in the temperature interval 573–777 K by in situ measurement of contact resistance, Auger depth profiling (ADP), and transmission electron microscopy. Correlation between evolution of contact resistance and measured Auger concentration profiles has been established and mechanisms incorporating rapid grain boundary diffusion, followed by defect-assisted diffusion into grain interiors (Type B kinetics), are proposed to explain the accelerated reactions observed. A modified Whipple model and two independent methods, based on ADP and contact resistance measurements, are used to calculate grain boundary and intragranular diffusion coefficients, respectively. The calculated grain boundary diffusion coefficient is (0.82 cm2/s) exp(−1.48eV/kT) for nickel in copper, and approximately 4×10−13 cm2/s for copper in nickel at 673 K. An average intragranular diffusion coefficient for nickel in copper is determined to be (2.6×10−6 cm2/s) exp(−1.38 eV/kT) by both methods, whereas ADP data yield a corresponding value of (5.2×10−8 cm2/s) exp(−1.51eV/kT) for copper in nickel. It is concluded that characterization of chemical composition and microstructure, combined with in situ measurement of concomitant electrical properties, provides a reliable description of interdiffusion mechanisms in this system.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 62 (1987), S. 1245-1250 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Circular gold dots, measuring about 200 μm in diameter and either 150 or 300 nm in thickness, have been produced on {100}, {110}, and {111} substrates of indium phosphide by a combination of vapor deposition and photolithographic processing, annealed at temperatures ranging from 420–460 °C, and subsequently examined by optical microscopy. During annealing, a reaction product, bounded by well-defined crystallographic planes of the substrate, forms, expands parabolically with annealing time, and eventually saturates due to the limited supply of gold. Generally, reactions proceed at least three times faster at {100} and {110} planes than at {111}In planes, in which reactions proceed about three times faster than at {111}P planes. Analysis of concomitant reaction kinetics yields an activation energy of 8.6±3.0 eV for reactions at {111}In planes. Results are interpreted in terms of a preferential interfacial reaction at {111}In planes, which is controlled by solid-state diffusion and eventual escape of phosphorus.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 61 (1992), S. 2987-2989 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Steady-state electromigration along grain boundaries in a monatomic polycrystalline thin film has been analyzed in a two-dimensional model by balancing the (applied) electric and (induced) stress driving forces to achieve a zero flux divergence. The continuity of chemical potential requires a unique stress normal to each of the three boundaries terminating at a given triple point. These stresses and the steady-state fluxes are determined by a set of linear equations subject to boundary conditions at the intersection of grain boundaries with the film edge (edge points). When the normal stress is assumed zero at all edge points, the stress typically attains maxima and minima at triple points, whereas, when the flux is assumed zero at all edge points, the stress typically builds up monotonically in the field direction.
    Type of Medium: Electronic Resource
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