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  • 1
    Electronic Resource
    Electronic Resource
    Measurement of thermal stress and stress relaxation in confined metal lines. I. Stresses during thermal cycling (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 1716-1724 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A method based on the bending beam technique has been developed to measure the thermal stresses of fine lines confined by a dielectric layer. This method has been employed to determine the thermal stress of Al (2 at. % Cu) lines passivated by a SiO2 overlayer between room temperature and 400 °C. The effect of quartz confinement was analyzed by matching the thermal displacement at the metal/passivation interfaces and by imposing a mechanical equilibrium condition on the structure. The analysis enables us to deduce the triaxial stress components of metal and passivation from measurements of the substrate bending parallel and perpendicular to the length direction of the lines. Results of the measurements show a substantial stress enhancement as a result of the confinement, with the stress level significantly higher than that of a passivated blanket film. Parameters that influence the magnitude of the stress components are line geometry, layer deposition conditions, and the extent of plastic deformation during thermal cycling. Results of the measurements are consistent with those determined using x-ray techniques.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354826
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  • 2
    Electronic Resource
    Electronic Resource
    Electromigration in Al(Cu) two-level structures: Effect of Cu and kinetics of damage formation (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 969-978 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The electromigration characteristics and kinetics of damage formation for Al(Cu,Si) line segments on a continuous W line and Al(Cu)/W two-level interconnect structures have been investigated. The mass transport as a function of temperature was measured using a drift-velocity technique. The flux divergence at the line/stud contact was found to be responsible for formation of open failure in the interconnect structure, as shown by a direct correlation observed between mass depletion at the contact and resistance increase of the line/stud chain. The depletion of Al at the stud contact is preceded by an incubation period during which Cu is swept out a threshold distance from the cathode of the line. This leads to a damage formation process which is controlled by both Cu electromigration along grain boundaries and dissolution of the Al2Cu precipitates. This is distinctly different from single-level interconnects measured using a conventional electromigration test site. Measurements of the mean failure lifetime in the two-level interconnect yield an activation energy of 0.58 eV for Al, in contrast to 0.78 and 0.83 eV for Al(0.5 wt % Cu) and Al(2 wt % Cu), respectively. The activation energies of the electromigration drift velocity were found to be 0.86 and 0.68 eV for Cu and Al in Al(2 wt % Cu, 3 wt % Si), respectively. These results enable one to infer that the kinetic process is controlled by electromigration of Cu along grain boundaries instead of by dissolution of the Al2Cu precipitates.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.354839
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  • 3
    Electronic Resource
    Electronic Resource
    Electromigration in two-level interconnect structures with Al alloy lines and W studs (1992)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 72 (1992), S. 291-293 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: It is demonstrated that electromigration testing needs to be performed in structures that reflect use conditions, such as when there is a flux divergence as provided by the W stud-Al(Cu) interface rather than in a simple planar structure. The Al(Cu)/W interface has been investigated using both drift velocity and resistometric techniques with pure Al, Al(0.5 wt. % Cu) and Al(2 wt. % Cu) lines on W studs for interlevel connections. It is shown that the mass depletion can be correlated to the resistance change and electromigration failure in line/stud chains. A new effect is demonstrated in that a critical length of Al has to be depleted on Cu before the Al can migrate; when such migration starts the Al catches up with the Cu rich region, leading to slower motion and the production of extrusions which will also cause failures by shorting to adjacent lines.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.352335
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  • 4
    Electronic Resource
    Electronic Resource
    A novel test structure for grating pitch determination with near-Angstrom accuracy (1990)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 68 (1990), S. 5381-5382 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: This communication describes a novel double-grating test structure which enables grating pitch-difference determination with angstrom accuracy. Edge acuity can also be estimated. The test structure is easily fabricated and rapidly evaluated with inexpensive equipment generally found in microstructure laboratories.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.347039
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  • 5
    Electronic Resource
    Electronic Resource
    Measurement of thermal stress and stress relaxation in confined metal lines. II. Stress relaxation study (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 74 (1993), S. 1725-1730 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The bending beam technique and stress analysis developed for stress measurements of fine line structures have been applied to investigate stress relaxation in confined Al (2 at. % Cu) line structures on a Si substrate. The observed relaxation of the line structure is compared with corresponding unpassivated and passivated layered film structures. The overall behavior of all structure is similar, showing an initial plastic deformation, then a fast relaxation in sequence with a log(time) slow relaxation. The kinetics of these relaxation processes are found to decrease due to the presence of the passivation and a higher degree of dielectric layer confinement. In addition, the relaxation behavior of the principal stress components of the line structure is anisotropic and does not vary monotonically with the annealing temperature. The results are attributed to the relaxation mechanism and interaction at the metal/dielectric interface.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.355327
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  • 6
    Electronic Resource
    Electronic Resource
    Reducing the induction to abortion interval in termination of second trimester pregnancies: a comparison of mifepristone with laminaria tent (1995)
    Oxford, UK : Blackwell Publishing Ltd
    BJOG 102 (1995), S. 0 
    Details
    ISSN: 1471-0528
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Objective To determine whether mifepristone (RU486) is more effective than laminaria tent in shortening the induction-abortion interval in termination of second trimester pregnancies with gemeprost.Design Prospective randomised comparative trial.Setting Department of Obstetrics and Gynaecology in a University teachng hospital.Subjects Sixty-two women undergoing termination of pregnancy in the second trimester.Interventions The women were allocated at random to one of the two treatment groups. The first group received 600 mg of mifepristone 36 h before administration of gemeprost. In the second group, a medium-sized laminaria tent was inserted 12 h before gemeprost. The pregnancies in both groups were terminated with vaginal gemeprost, 1 mg every 3 h up to a maximum of 5 mg/day.Main outcome measures Induction-abortion intervals, amount of gemeprost required, and incidence of side effects.Results The median induction-abortion interval in the mifepristone group (75 h) was significantly shorter than that in the laminaria tent group (11 h) and significantly fewer gemeprost pessaries were required. There was no significant difference in the amount of narcotic analgesics required or the incidence of side effects between the two groups.Conclusions Mifepristone is more effective than laminaria tent in shortening the induction-abortion interval in termination of second trimester pregnancies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1471-0528.1995.tb11404.x
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  • 7
    Electronic Resource
    Electronic Resource
    A NOVEL REACTION BETWEEN GLYOXYLATE AND TETRAHYDROFOLATE1 (1960)
    s.l. : American Chemical Society
    Journal of the American Chemical Society 82 (1960), S. 5957-5958 
    Details
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ja01507a046
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  • 8
    Electronic Resource
    Electronic Resource
    Characteristics of thermal stresses in Al(Cu) fine lines. I. Unpassivated line structures (1995)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 78 (1995), S. 945-952 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The stress evolution of unpassivated Al(Cu) fine lines under thermal cycling has been investigated as a function of linewidth using a bending beam technique. The results show that the stresses parallel (σ(parallel)) and perpendicular (σ⊥) to the line direction are lower than those measured for thin films as a consequence of stress reduction at the line edges. The edge effect is particularly effective in reducing σ⊥, although σ(parallel) is also affected. With decreasing linewidth, the effect became more pronounced, leading to an increasingly unequal biaxial stress state and a reduction in line deformation. The observed linewidth dependence can be satisfactorily accounted for by analytic or finite element calculations of the average line stresses as a function of the line aspect ratio. Results of this study validates the use of the bending beam technique for measuring the average stresses in fine line structures. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.360288
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  • 9
    Electronic Resource
    Electronic Resource
    Characteristics of thermal stresses in Al(Cu) fine lines. II. Passivated line structures (1995)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 78 (1995), S. 953-961 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The effects of oxide confinement on the thermal stress and yield behavior of passivated Al(Cu) line structures have been studied as a function of linewidth to submicron dimensions using a bending-beam technique. Principal stresses in the passivated line structures were deduced based on a micromechanical analysis of the curvatures of periodic line structures with lines oriented parallel and perpendicular to the beam direction. Results from the passivated Al(Cu) lines show that with decreasing linewidth, the magnitude of the principal stress components become higher until the line aspect ratio approaching one, then decreased. This behavior is consistent with theoretical predictions by analytical methods and finite element analyses. The stress behavior of the oxide passivation has also been deduced and its magnitude depended on the oxide morphology at the sidewall of the lines. Our result indicates a high level of stress in the sidewall which may cause crack formation during thermal cycling. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.360289
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  • 10
    Electronic Resource
    Electronic Resource
    Grain boundary diffusion and its effects on the magnetic properties of Co/Cu and Co/Cr thin film bilayers (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 75 (1994), S. 5052-5060 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: X-ray photoelectron spectroscopy has been used to investigate grain boundary diffusion of Cu and Cr through 1000-A(ring)-thick Co films in the temperature range of 300–400 °C. Grain boundary diffusivities were determined by modeling the accumulation of Cu or Cr on Co surfaces as a function of time at fixed annealing temperature. The grain boundary diffusivity of Cu through Co has a diffusion coefficient D0,gb of 2×104 cm2/s and an activation energy Ea,gb of 2.4 eV. Similarly, Cr grain boundary diffusion through Co thin films exhibits a D0,gb of 6×10−2 cm2/s and an Ea,gb of 1.8 eV. The Co film microstructure has been investigated before and after annealing by x-ray diffraction and transmission electron microscopy. Extensive grain growth and texturing of the magnetic film occurred during annealing for Co deposited on a Cu underlayer which is believed to influence the grain boundary diffusion process. In contrast, the microstructure of Co deposited on a Cr underlayer remained relatively unchanged upon annealing. The difference in grain growth between the two bilayers has been suggested to account for the large disparity in activation energies. Magnetometer measurements have shown that increased in-plane coercivity Hc, reduced remanence squareness S, and reduced coercive squareness S* result from grain boundary diffusion of Cu and Cr into the Co films.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.355747
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