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  • Open AccessOpen Access

    ARTICLE

    Modeling of the Electronic Properties of Vertical Quantum Dots by the Finite Element Method

    Philippe Matagne1, Jean-Pierre Leburton2, Jacques Destine, Guy Cantraine3
    CMES-Computer Modeling in Engineering & Sciences, Vol.1, No.1, pp. 1-10, 2000, DOI:10.3970/cmes.2000.001.001
    Abstract We investigate the quantum mechanical properties and single-electron charging effects in vertical semiconductor quantum dots by solving the Schrödinger and Poisson (SP) equations, self-consistently. We use the finite element method (FEM), specifically the Bubnov-Galerkin technique to discretize the SP equations. Owing to the cylindrical symmetry of the structure, the mesh is generated from hexahedral volume elements. The fine details of the electron spectrum and wavefunctions in the quantum dot are obtained as a function of macroscopic parameters such as the gate voltage, device geometry and doping level. The simulations provide comprehensive data for the analysis of the experimental data of… More >

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    1622

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    1259

  • Open AccessOpen Access

    ARTICLE

    Simulation of Anisotropic Crystalline Etching using a Continuous Cellular Automata Algorithm

    Zhenjun Zhu, Chang Liu1
    CMES-Computer Modeling in Engineering & Sciences, Vol.1, No.1, pp. 11-20, 2000, DOI:10.3970/cmes.2000.001.011
    Abstract We present results on the development of an anisotropic crystalline etching simulation (ACES) program based on a new continuous Cellular Automata (CA) model, which provides improved spatial resolution and accuracy compared with the conventional and the stochastic CA \mbox{methods}. Implementation of a dynamic CA technique provides increased simulation speed and reduced memory requirement (5x). A first ACES software based on common personal computer platforms has been realized. Simulated results of etching match well with experiments. We have developed a new methodology to obtain the etch-rate diagram of anisotropic etching efficiently using both experimental and numerical techniques. More >

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    2447

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    2143

  • Open AccessOpen Access

    ARTICLE

    Analysis of Realistic Large MEMS Devices

    Per Ljung1, Martin Bächtold2, Mirko Spasojevic2
    CMES-Computer Modeling in Engineering & Sciences, Vol.1, No.1, pp. 21-30, 2000, DOI:10.3970/cmes.2000.001.021
    Abstract This paper presents AutoMEMS®, a numerical simulation environment to efficiently analyze the behavior of large real-world MEMS designs. By automating surface-based model generation, meshing and field solver tools, it is possible to rapidly model large complex MEMS devices. More >

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    1471

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    1153

  • Open AccessOpen Access

    ARTICLE

    Accurate Modelling and Simulation of Thermomechanical Microsystem Dynamics

    S. Taschini1, J. Müller2, A. Greiner2, M. Emmenegger1, H. Baltes1, J.G. Korvink2
    CMES-Computer Modeling in Engineering & Sciences, Vol.1, No.1, pp. 31-44, 2000, DOI:10.3970/cmes.2000.001.031
    Abstract We present three techniques to accurately model the thermomechanical response of microsystem components: a new, accurate and stable Kirchhoff-Love multi-layered plate model implemented as an Argyris finite element, a model for the amplitude fluctuations of vibrational modes in micro-mechanical structures within a gaseous environment, and the consistent refinement of a finite element mesh in order to maximize the computational accuracy for a given mesh size. We have implemented these techniques in our in-house MEMS finite element program and accompanying Monte Carlo simulator. We demonstrate our approach to dynamic modeling by computing the thermomechanical response of a CMOS AFM beam. More >

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    1475

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    1229

  • Open AccessOpen Access

    ARTICLE

    A Methodology and Associated CAD Tools for Support of Concurrent Design of MEMS

    B. F. Romanowicz1, M. H. Zaman1, S. F. Bart1, V. L. Rabinovich1, I. Tchertkov1, S. Zhang1, M. G. da Silva1, M. Deshpande1, K. Greiner1, J. R. Gilbert1, Shawn Cunningham2
    CMES-Computer Modeling in Engineering & Sciences, Vol.1, No.1, pp. 45-64, 2000, DOI:10.3970/cmes.2000.001.045
    Abstract Development of micro-electro-mechanical systems (MEMS) products is currently hampered by the need for design aids, which can assist in integration of all domains of the design. The cross-disciplinary character of microsystems requires a top-down approach to system design which, in turn, requires designers from many areas to work together in order to understand the effects of one sub-system on another. This paper describes current research on a methodology and tool-set which directly support such an integrated design process. More >

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    1511

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    1258

  • Open AccessOpen Access

    ARTICLE

    Modelling and Validation of Contribions to Stress in the Shallow Trench Isolation Process Sequence

    K. Garikipati1, V.S. Rao2, M.Y. Hao3, E. Ibok4, I. de Wolf5, R. W. Dutton6
    CMES-Computer Modeling in Engineering & Sciences, Vol.1, No.1, pp. 65-84, 2000, DOI:10.3970/cmes.2000.001.065
    Abstract This work is based upon a careful rendering of mechanics and mathematics to describe the phenomena that influence the stress engendered by the Shallow Trench Isolation process. The diffusion-reaction problem is posed in terms of fundamental mass balance laws. Finite strain kinematics is invoked to model the large expansion of SiO2, dielectrics are modelled as viscoelastic solids and annealing-induced density relaxation of SiO2 is incorporated as a history-dependent process. A levelset framework is used to describe the moving Si/SiO2 interface. Sophisticated finite element methods are employed to solve the mathematical equations posed for each phenomenon. These include the incorporation of… More >

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    1467

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    1385

  • Open AccessOpen Access

    ARTICLE

    Effect of Growth Direction on Twin Formation in GaAs Crystals Grown by the Vertical Gradient Freeze Method

    A.N. Gulluoglu1, C.T. Tsai2
    CMES-Computer Modeling in Engineering & Sciences, Vol.1, No.1, pp. 85-90, 2000, DOI:10.3970/cmes.2000.001.085
    Abstract Twins in growing crystals are due to excessive thermal stresses induced by the temperature gradients developed during the growth process. Twinning is an important defect in advanced semiconductor crystals such as GaAS and InP. The objective of this study is to develop a computational model to predict the twin formation in the Gallium Arsenide (GaAs) crystals grown by the vertical gradient freeze method (VGF). A quantitative quasi-steady state thermal stress model is developed here for predicting the twinning formation in GaAs grown by VGF. The thermoelastic stresses in VGF grown crystal are calculated from a two-dimensional finite element analysis. Deformation… More >

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    1548

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    1169

  • Open AccessOpen Access

    ARTICLE

    Strength Evaluation of Electronic Plastic Packages Using Stress Intensity Factors of V-Notch

    Toru Ikeda1, Isao Arase, Yuya Ueno, Noriyuki Miyazaki
    CMES-Computer Modeling in Engineering & Sciences, Vol.1, No.1, pp. 91-98, 2000, DOI:10.3970/cmes.2000.001.091
    Abstract In electronic devices, the corners of joined dissimilar materials exist between plastic resin and a die pad or a chip. Failure of the plastic resin is often caused from these corners during the assembly process or the operation of products. The strength evaluation of the corner is important to protect the failure of plastic packages. To evaluate the singular stress field around a corner, we utilize the stress intensity factors of the asymptotic solution for a corner of joined dissimilar materials. We show that the accurate stress intensity factor can be analyzed by the displacement extrapolation method using the displacement… More >

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    1438

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    1116

  • Open AccessOpen Access

    ARTICLE

    Cracking of GSO Single Crystal Induced by Thermal Stress

    N. Miyazaki1, T. Tamura2, K. Yamamoto1
    CMES-Computer Modeling in Engineering & Sciences, Vol.1, No.1, pp. 99-106, 2000, DOI:10.3970/cmes.2000.001.099
    Abstract Quantitative estimation of the failure of a gadolinium orthosilicate (Gd2SiO5, hereafter abbreviated as GSO) single crystal induced by thermal stress was investigated. A GSO cylindrical test specimen was heated in a silicone oil bath, then subjected to large thermal stress by room temperature silicone oil. Cracking occurred during cooling. The transient heat conduction analysis was performed to obtain temperature distribution in the test specimen at the time of cracking, using the surface temperatures measured in the test. Then the thermal stress was calculated using the temperature profile of the test specimen obtained from the heat conduction analysis. It is found… More >

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    1585

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    1183

  • Open AccessOpen Access

    ARTICLE

    Numerical Simulation of Fatigue Crack Growth in Microelectronics Solder Joints

    K. Kaminishi1, M. Iino2, H. Bessho2, M. Taneda3
    CMES-Computer Modeling in Engineering & Sciences, Vol.1, No.1, pp. 107-110, 2000, DOI:10.3970/cmes.2000.001.107
    Abstract An FEA (finite element analysis) program employing a new scheme for crack growth analysis is developed and a prediction method for crack growth life is proposed. The FEA program consists of the subroutines for the automatic element re-generation using the Delaunay Triangulation technique, the element configuration in the near-tip region being provided by a super-element, elasto-inelastic stress analyses, prediction of crack extension path and calculation of fatigue life. The FEA results show that crack extension rate and path are controlled by a maximum opening stress range, Δσθmax, at a small radial distance of r = d, where d is chosen… More >

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    1461

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    1166

  • Open AccessOpen Access

    ARTICLE

    Design and Fabrication of an Electrostatic Variable Gap Comb Drive in Micro-Electro-Mechanical Systems

    Wenjing Ye1, Subrata Mukherjee2
    CMES-Computer Modeling in Engineering & Sciences, Vol.1, No.1, pp. 111-120, 2000, DOI:10.3970/cmes.2000.001.111
    Abstract Polynomial driving-force comb drives are designed using numerical simulation. The electrode shapes are obtained using the indirect boundary element method. Variable gap comb drives that produce combinations of linear, quadratic, and cubic driving-force profiles are synthesized. This inverse problem is solved by an optimization procedure. Sensitivity analysis is carried out by the direct differentiation approach (DDA) in order to compute design sensitivity coefficients (DSCs) of force profiles with respect to parameters that define the shapes of the fingers of a comb drive. The DSCs are then used to drive iterative optimization procedures. Designs of variable gap comb drives with linear,… More >

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    1312

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    1319

  • Open AccessOpen Access

    ARTICLE

    A Meshless Method for the Numerical Solution of the 2- and 3-D Semiconductor Poisson Equation

    C.J. Wordelman, N.R. Aluru, U. Ravaioli1
    CMES-Computer Modeling in Engineering & Sciences, Vol.1, No.1, pp. 121-126, 2000, DOI:10.3970/cmes.2000.001.121
    Abstract This paper describes the application of the meshless Finite Point (FP) method to the solution of the nonlinear semiconductor Poisson equation. The FP method is a true meshless method which uses a weighted least-squares fit and point collocation. The nonlinearity of the semiconductor Poisson equation is treated by Newton-Raphson iteration, and sparse matrices are employed to store the shape function and coefficient matrices. Using examples in two- and three-dimensions (2- and 3-D) for a prototypical n-channel MOSFET, the FP method demonstrates promise both as a means of mesh enhancement and for treating problems where arbitrary point placement is advantageous, such… More >

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    1369

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    1080

  • Open AccessOpen Access

    ARTICLE

    Optimal Design of Computer Experiments for Metamodel Generation Using I-OPTTM

    Selden B. Crary1, Peter Cousseau2, David Armstrong1, David M. Woodcock3, Eva H. Mok1, Olivier Dubochet4, Philippe Lerch4, Philippe Renaud2
    CMES-Computer Modeling in Engineering & Sciences, Vol.1, No.1, pp. 127-140, 2000, DOI:10.3970/cmes.2000.001.127
    Abstract We present a new and unique software capability for finding statistical optimal designs of deterministic experiments on continuous cuboidal regions. The objective function for the design optimization is the minimization of the expected integrated mean squared error of prediction of the metamodel that will be found, subsequent to the running of the computer simulations, using the best linear unbiased predictor (BLUP). The assumed response-model function includes an unknown, stochastic term, Z. We prove that this criterion, which we name IZ-optimality, is equivalent to I-optimality for non-deterministic experiments, in the limit of zero correlations among the Z's for different inputs. An… More >

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    1573

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    1125

  • Open AccessOpen Access

    ARTICLE

    Multidimensional Semiconductor Device and Micro-Scale Thermal Modeling Using the PROPHET Simulator with Dial-an-Operator Framework

    Anand L. Pardhanani1, Graham F. Carey1
    CMES-Computer Modeling in Engineering & Sciences, Vol.1, No.1, pp. 141-150, 2000, DOI:10.3970/cmes.2000.001.141
    Abstract Rapid prototyping tools that combine powerful numerics with a flexible applications interface can play a significant role in micro-scale modeling and simulation. We demonstrate this idea using the PROPHET simulator. In the first part of the investigations we extend the simulator's capability to allow analysis of carrier transport in deep submicron MOSFETs using a hydrodynamic model. The model is numerically implemented within PROPHET's dial-an-operator framework by adding certain "flux'' routines. Once implemented, the model becomes available for use in any number of spatial dimensions. We present results for MOSFET type test problems in one and two dimensions. The second application… More >

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    1519

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    1101

  • Open AccessOpen Access

    ARTICLE

    Making a PROPHET

    Conor Rafferty1, R. Kent Smith
    CMES-Computer Modeling in Engineering & Sciences, Vol.1, No.1, pp. 151-160, 2000, DOI:10.3970/cmes.2000.001.151
    Abstract The PROPHET simulator is a software system for solving partial differential equations (PDEs) in time and 1,2 or 3 space dimensions. When equipped with appropriate modules, it can be configured as a process simulator or a device simulator, with application to modeling semiconductor fabrication processes and transistor behavior. The simulator is designed with three main goals: efficiency, geometric flexibility, equation extensibility. The first two distinguish it from canned packages such as Mathematica, which do not easily allow the use of arbitrary shapes or grids and are not tuned to solve systems with 105 or 106 unknowns. The third distinguishes it… More >

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    1483

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    1051

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