Open Access
ARTICLE
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 >
Open Access
ARTICLE
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 >
Open Access
ARTICLE
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 >
Open Access
ARTICLE
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 >
Open Access
ARTICLE
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 >
Open Access
ARTICLE
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 >
Open Access
ARTICLE
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 >
Open Access
ARTICLE
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 >
Open Access
ARTICLE
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 >
Open Access
ARTICLE
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 >
Open Access
ARTICLE
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 >
Open Access
ARTICLE
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 >
Open Access
ARTICLE
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 >
Open Access
ARTICLE
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 >
Open Access
ARTICLE
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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