Characterization method of thermomechanical parameters for microelectronic materials

Reliability of thermomechanical simulations is critically linked to the accuracy of the mechanical properties that govern the behaviour of structure, like Young's modulus (E) and coefficient of thermal expansion (CTE). For many cases, the values found in literatures are dealing with bulk properties without detailed information on temperature effects. To address such issues, it is necessary to measure the materials parameters as a function of temperature. The measurement of CTE is usually accomplished by evaluating the thermal deflections of a subjected material layer deposited on a substrate, providing that E is known at a specific temperature of experiment. A bilayer method, based on theory of elasticity, is proposed to determine both E and CTE for a given temperature with a good resolution. This paper presents the theoretical analysis, the design and process of the microsystem test structures, and the main calculation results.     

Cubic millimeter power inductor fabricated in batch-type wafer technology

A hybrid technology for the realization of three-dimensional (3-D) miniaturized power inductors is presented. Our devices consist of planar Cu coils on polyimide substrates, and mm-size ferrite magnetic cores, obtained by three-dimensional micro-patterning of ferrite wafers using powder blasting. The coils are realized using an in-house developed high-resolution polyimide spinning and Cu electroplating process. Winding widths down to 5 /spl mu/m have been obtained and total device volumes are ranging between 1.5 and 10 mm/sup 3/. Inductive and resistive properties are characterized as a function of frequency; inductance values in the 100 /spl mu/H range have been obtained.     

Corrosion protection of iron by polypyrrole modified by copper using the cementation process

Polypyrrole (PPy) coatings have been deposited on iron from aqueous oxalic acid solution at different current densities. The polymer deposit obtained at a current density of 2 mA cm⁻² yields strongly adherent and smooth PPy layers. The modification of the film by incorporation of copper microparticles using the cementation process was applied. The resulting PPy/Cu film electrodes were characterized by scanning electron microscopy and EDX analysis. The protective performance against corrosion of these films is evaluated by using open circuit potential monitoring in highly corrosive solution (3% NaCl + HCl, pH 1). The results obtained were promising in the protection against corrosion.     

Effect of thickness stretching and porosity on mechanical response of a functionally graded beams resting on elastic foundations

The novelty of this paper is the use of an efficient beam theory for bending, free vibration and buckling analysis of functionally graded material (FGM) beams on two-parameter elastic foundation. The present theory accounts for both shear deformation and thickness stretching effects by a parabolic variation of all displacements across the thickness, and satisfies the stress-free boundary conditions on the upper and lower surfaces of the beam without requiring any shear correction factor. Due to porosities, possibly occurring inside FGMs during fabrication, it is therefore necessary to consider the vibration, bending and buckling behaviors of beams having porosities in this work. The equation of motion for FGM beams is obtained through Hamilton’s principle. The closed form solutions are obtained by using Navier technique, and then fundamental frequencies are found by solving the results of eigenvalue problems. The validity of the present theory is investigated by comparing some of the present in literature. It can be concluded that the proposed theory is accurate and simple in solving the bending, free vibration and buckling behaviors of FGM sandwich beams.     

Power MOSFET quality and robustness enhancement with a new QBD characterization performed at probe–die–wafer level

The quality of the gate oxide is a central parameter for power MOSFET devices dedicated to automotive applications. Reliability is systematically evaluated through electrical tests. The purpose of this study is to apply the Q_BD test directly at probe–die–wafer level and to correlate its results with reliability test conclusions. In other words, this new kind of Q_BD test is a monitor of power MOSFET robustness which helps identify extrinsic failures and the process steps responsible. In summary, it is an accurate and fast measurement method of identifying weakened parts and enhancing device quality.     

Analysis of the transverse cracking in hybrid cross-ply composite laminates

A modified shear-lag analysis, taking into account the concept of interlaminar shear stress, is employed to evaluate the effect of transverse cracks on the stiffness reductions in different glass/epoxy and graphite/epoxy hybrid cross-ply laminates. The modified shear-lag model is proposed that assumes interlaminar adhesive layer between two neighbouring layers transferring not only interlaminar shear stress but also normal stress. The stress distribution is solved by the used model which rigorously satisfies the stress equilibrium equations, boundary conditions and the traction continuity at interfaces between layers.     

Preparation on iron of a polypyrrole (PPy) electrode modified with copper by the electrochemical cementation process

Conducting polypyrrole electrodes obtained under galvanostatic electropolymerization on iron from aqueous solutions of pyrrole and oxalic acid were modified with copper particles using the electrochemical cementation process. The electrochemical response of these modified electrodes was compared to that of the unmodified polymer electrode and also to that of bare metallic copper. The modified polypyrrole electrode showed noticeable enhancement for the rate of proton reduction.     

Smart 3-D Finite-Element Modeling for the Design of Ultra-Low On-Resistance MOSFET

A 3-D electrical finite-element model (FEM) for the design of an ultra-low on-state resistance power MOSFET device is presented. Model building and layer conductivity are discussed to take into account microscopic, technological, and electrical effects, such as metal step coverage and MOS behavior of each elementary cell of the transistor. Model simplifications are also presented to ensure time-efficient simulations. FEM gauging is then achieved, by comparing simulation results to electrical measurements, on devices subjected to top metallization debiasing effects. Simulations show a good agreement with measurements for result errors at less than 2%. The aim of this paper is to provide an accurate estimation of the contribution of parasitic elements such as the shape and number of power bonding wires or top metallization thickness to power device on-state resistance (R_ON). The 3-D electrical FEM is a mandatory first step towards an accurate electrothermal FEM for the design of efficient power products.     

Soluble conducting poly(aniline-co-orthotoluidine) copolymer as corrosion inhibitor for carbon steel in 3% NaCl solution

The copolymer poly (aniline-co-o-toluidine) noted poly(ANI-co-OT) is chemically synthesized, and characterized by FT-IR, UV-Vis, TGA and XRD techniques. The results show that this copolymer presents new structures and it is more thermally stable than the corresponding parent homopolymers. It is found that it is soluble in dimethylformamide (DMF), while the homopolymers have a low solubility. Techniques such as potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) have been employed to study the inhibition effects of this copolymer on the corrosion of carbon steel in 3% NaCl solution. The results show an increase in inhibition efficiency as a function of copolymer concentration to attain an optimum (70%) for a concentration close to 100 ppm. This is due to the higher coverage of the carbon steel electrode surface as shown by the Temkin adsorption isotherm. The Potentiodynamic polarisation studies reveal that this copolymer acts as a mixed-type inhibitor. The results obtained by potentiodynamic and EIS techniques are in good agreement.     

A vehicle plate recognition system based on deep learning algorithms

Multimedia Tools and Applications - In modern life, the massive number of vehicles makes it hard for a human being to process its related information. So, it is important to build an automatic...