Thickness-stress relations in aluminum thin films

The physical properties of aluminum thin films depend strongly on their microstructure, which can be characterized using different techniques. In the present work, aluminum thin films—grown with different thickness on silicon substrates—were analyzed by atomic force microscopy (AFM) and grazing incidence x-ray techniques. The AFM was used as a high-resolution profilemeter for measuring edge angles, step heights, surface microstructure, and roughness. The structural properties (such as crystallographic orientation, crystallite size, and phase identification) were analyzed by grazing incidence x-ray diffraction. For small thickness, AFM images show small nucleation sites because of the short time of growth. Grain size grows as the thickness increases, and film morphology seems to be uniform with large grains. The AFM results of as-grown films show a linear increase in roughness along with thickness. Roughness values decrease with aging time after film preparation, until a constant value is observed. All films mainly have (111) orientation, and its intensity grows with film thickness, with respect to the (200) and (220) peaks. As the film thickness increases, the surface stress decreases.     

Synthesis, Structure, and Physicochemical Characteristics of Rutherfordite and Tetrasodium Uranyl Tricarbonate

The optimum procedures for synthesis of UO₂CO₃ and Na₄[UO₂(CO₃)₃] were developed. The structures of these compounds and their thermal decomposition were studied by X-ray diffraction, precision IR spectroscopy, and thermography. The standard enthalpy of formation of crystalline Na₄[UO₂(CO₃)₃] at 298.16 K was determined to be -4010.0±8.0 kJ mol^{- 1}.     

Analyses of the practical adhesion strengths of the metal/polymer interfaces in electronic packaging

There is a plethora of techniques to measure the adhesion strength of metal/polymer interfaces. However, the practical adhesion strength, which is the work done in separating the film from the substrate (or one film from another), is very sensitive to the test methods and the mechanical effects, such as the residual stress, thickness and mechanical properties of the layers, strain rate, and phase angle. Deriving intrinsic-adhesion properties of the interfaces, which are independent of such parameters, from the practical adhesion-strength measurements is a formidable task. In the present work, data from the three commonly used adhesion tests; pull-out, 90°-peel, and T-peel tests are compared with the intrinsic-adhesion properties of the interface, such as the interface-fracture toughness or the interface-fracture energy, and their implications are discussed. Material systems analyzed were Cu-based lead frame/epoxy-molding compound (EMC) and Cu/Cr/polyimide.     

Deposition mechanisms in langmuir-blodgett films

As part of a study of the possible application of polymerisable Langmuir-Blodgett (LB) films as ultra-fine-line e-beam resists, an investigation of the variation of film structure of 22-tricosenoic acid with differing deposition conditions has been made. Unexpected effects with significant implications for deposition speed and resist sensitivity have been observed, and the new techniques for film characterisation developed during the investigation have resulted in a revised model of deposition explaining the observed independence of the disorder causing optical scattering and the macroscopic features observed by polarised microscopy.     

Determining pheromone content of hairpencils from individual virgin males ofPseudaletia unipuncta (Haw.) (Lepidoptera: Noctuidae)

Levels of benzaldehyde recovered from virginPseudaletia unipuncta (Haw.) males were not influenced by (1) the time hairpencils remained in the solvent (1-72 hr), (2) anesthetization or agitation of males prior to excision of hairpencils, or (3) the time (photophase or scotophase) that hairpencils were excised. Thus the interindividual variability observed is not a methodological artifact. Most males had similar concentrations in both hairpencils, although in some cases only one hairpencil contained pheromone. In one case, a male with partially extruded hairpencils had no benzaldehyde at all. Neither pupal weight nor hairpencil length proved to be reliable indicators of pheromone content.Contribution No. 373, Département de biologie, Université Laval.     

New linear codes over F/sub 5/ obtained by tripling method and improvements on bounds

One of the most important problems of coding theory is to construct codes with the best possible minimum distance. We further generalize the method first introduced by Gulliver and Harada (see Des., Codes Cryptogr, vol. 22, no. 1, p.89-96, 2001) and later generalized by the present authors, and obtain new linear codes which improve the best known minimum-distance bounds of certain linear codes. We have found eight new linear codes over F/sub 5/ with improved minimum distances. We introduce a generalized version of a Gray map, then we give definitions of quasi- and nearly quasi-cyclic codes. We conclude by giving the parameters of new linear codes with their generator matrices.     

Measuring errors of amplitude and phase for vibratory accelerations when testing objects

Measurement Techniques -     

Liquid crystalline polymers as additives to enhance the device properties of low molecular mass liquid crystals

Magnetic and electric fields have been used to determine the splay (k₁₁) and bend (k₃₃) elastic constants in a series of polymer/monomer liquid crystal solutions using the well known Freedericksz transition technique. Measurements have been carried out as a function of concentration and temperature. The polymer used was a smectogenic polysiloxane side chain liquid crystal with both cyanobiphenyl and benzoate ester side groups. The monomeric solvent was the nematogen 4-n-pentyl-4′-cyanobiphenyl. All of the solutions studied were nematogenic up to a concentration of 40% w/w. It has been shown that k₁₁, k₃₃ and $\text{k}{}_{33}\text{k}{}_{11}$ all decrease with increasing polymer concentration and that at high enough concentrations $\text{k}{}_{33}\text{k}{}_{11}$ tends to become independent of temperature. The implications of these results are discussed in terms of the performance of the most common liquid crystal display, i.e. the twisted nematic device.