Query: element edge tcad discretization

Candidate papers:

abstract: Technology computer aided design (TCAD) semiconductor device simulators solve partial differential equations (PDE) using the finite volume method (FVM) or related methods. While this approach has been in use over several decades, its methods continue to be extended, and are still applicable for investigating novel devices. In this paper, we present an element edge based (EEB) FVM discretization approach suitable for capturing vector field effects. Drawing from a 2D approach in the literature, we have extended this method to 3D. We implemented this method in a TCAD semiconductor device simulator, which uses a generalized PDE (GPDE) approach to simulate de vices with the FVM. We describe how our EEB method is compatible with the GPDE approach, allowing the modeling of vector effects using scripting. This method is applied to solve polarization effects in a 3D ferro capacitor, and a 2D ferroelectric field effect transistor. An example for field dependent mobility in a 3D MOSFET is also presented.
title: Element Edge Based Discretization for TCAD Device Simulation
venue: IEEE Transactions on Electron Devices
year: 2021

abstract: CMOS scaling became popular among researchers and the semiconductor industry since it provides many advantages like faster speed, higher performance, and increased integration density on a chip. Despite the above advantages, short channel effects are a major concern for planar devices at lower technology nodes which led to the development of multiple gate FETs (MugFET) such as Nanosheet FETs (NSFET) Nanowire FET (NWFET) and FinFET as a replacement for planar MOSFETs. Among all these MugFETs, for sub 7nm technology node, NSFETs are a potential replacement of FinFET and NWFETs due to their high drive current and speed. However, the small channel area and doping profile make these MugFETs more susceptible to Process induced variation. In this thesis, some of these issues are discussed and solutions are proposed. The work presented in this thesis is done using Synopsys Sentaurus TCAD and all the characterization is done using Cascade manual prober along with Keysight B1500 parameter analyzer. In the initial part of the thesis, CMOS FETs are designed and simulated using Sentaurus TCAD to match Semiconductor Laboratory (SCL) CMOS 0.18mm device's physical design and electrical characteristics. Id Vgs of n and p type FETs are measured in linear as well as in the saturation region and finally calibrated using the Sentaurus TCAD model. SOI device's faster speed, resistance to latch up, and immunity against radiation make it preferable over conventional planar devices. PD SOI and FD SOI FETs are also designed to a specific 0.18um CMOS target using a calibrated TCAD model for radiation analysis. MugFETs with small channel area are subject to Line edge roughness (LER) due to process induced variation. LER can result in a high mismatch in FET's electrical characteristics. In this thesis, a 3 D LER model has been taken for the accurate analysis of mismatch in NS and NW FETs electrical characteristics. The mismatch performance of NSFET is investigated and reported for different NS widths. Also, SCE performance parameters, like DIBL (mV) and SS (mV/dec) sensitivity to LER are investigated in this chapter. Moreover, the Junctionless mode devices (JL) are preferred over Inversion mode (IM) devices for nanoscale FETs design due to their simple fabrication process, high drive current, and feasibility of doing short channel length design. However, JL FETs are more susceptible to process induced variation. This thesis also includes a study of matching the performance of inversion (INV) and junctionless (JL) NS/NW FETs devices for 3 D LER. Semiconductor devices are also being widely used in space for various applications, also affected by the presence of Cosmic rays consist of different particles such as heavy ions, neutrons, protons, electrons, alpha particles, and gamma rays. Among these cosmic ray particles, heavy ions cause a change in the state of memory element or temporary circuit failure due to instantaneous transient current spike in devices. In the next part of the thesis, heavy ion induced single event transient (SET) in bulk and SOI NSFET are discussed. Vertically stacked nanosheets are designed and simulated using the inbuilt heavy ion Sentaurus TCAD model. SET current in bulk and SOI NSFETs for different device dimensions are investigated and discussed in this thesis. Also, the effect of the different angles of ion incidence on SET performance is analyzed. SOI NSFETs show a distinct advantage over bulk devices for heavy ion SET. Further, different 3 D SOI MugFETs, such as FinFET, NSFET, and NWFET are simulated for SET due to heavy ion irradiation and compared. Finally, an empirical model is also presented in this thesis to predict the SET current with physical design parameters of MugFETs, and as well as the heavy ion model parameters. Physical design as well as heavy ion parameters, such as nanosheet fin width/ thickness, the diameter of a nanowire, linear energy transfer (LET) angle of incidence, and channel doping are incorporated to accurately predict SET due to heavy ion irradiation on these MugFETs.
title: TCAD Based Modelling of Line Edge Roughness and Radiation Effects in Advanced CMOS Devices
year: 2021

abstract: The scalable iterative solution of strongly coupled three dimensional incompressible resistive magnetohydrodynamics (MHD) equations is very challenging because disparate time scales arise from the electromagnetics, the hydrodynamics, as well as the coupling between these systems. This study considers a mixed finite element discretization of a dual saddle point formulation of the incompressible resistive MHD equations using a stable nodal (Q2/Q1) discretization for the hydrodynamics and a stable edge node discretization of a reduced form of the Maxwell equations. This paper presents new approximate block factorization preconditioners for this system which reduce the system to approximate Schur complement systems that can be solved using algebraic multilevel methods. These preconditioners include a new augmentation based approximation for the magnetic induction saddle point system as well as efficient approximations of the Schur complements that arise from the complex coupling between the Navier Stokes eq.
author_names: Edward G Phillips

John N Shadid

Eric C Cyr

Howard C Elman

Roger P Pawlowski
title: Block Preconditioners for Stable Mixed Nodal and Edge finite element Representations of Incompressible Resistive MHD
venue: SIAM J. Sci. Comput.
year: 2016

abstract: Abstract A new recovery method of edge elements for Maxwell's equations is proposed to reduce the recovery problem into one dimensional settings by using the local symmetry projection. The recovered method is applied to both Nedelec interpolation and edge finite element approximation. Superconvergence results are established for both the postprocessed Nedelec interpolation and the recovered edge finite element approximation in a discrete norm. Numerical examples are presented to illustrate our theoretical analysis.
author_names: Chao Wu

Yunqing Huang

Nianyu Yi

Jinyun Yuan
title: Superconvergent recovery of edge finite element approximation for Maxwell's equations
year: 2020

abstract: In order to couple external circuits to edge element discretized electromagnetic models, with full field equations, global constraints involving voltages or currents need to be enforced. There is no canonical way to impose a voltage or a current without additional modeling information on the distribution of field sources that rely on topological concepts. In this article, a fast solution of field sources within massive conductors in static and dynamic problems is proposed. Global basis functions, required to cope with non trivial coil topologies, are directly generated by an iterative solver rather than pre computing source fields, e.g. by tree cotree decomposition.
author_names: Federico Moro

Lorenzo Codecasa
title: Enforcing Lumped Parameter Excitations in Edge Element Formulations by Using a Fast Iterative Approach
venue: IEEE Transactions on Magnetics
year: 2020

abstract: The high speed and high efficient cutting is the future of the mechanical processing technology. The tool edge preparation prolongs the service life of the tool, elevates the machined surface quality and the cutting performance through modification of the cutting edge contour, micro topography and microstructure in the edge area. It is necessary to study the edge preparation mechanism to realize the importance of the high speed and high efficiency cutting. The mathematical model of the milling tool motion trajectory is built up using the edge preparation characteristics of the planetary motion. Based on the basic principle of the discrete element method and the Hertz contact theory, the simulation model of the tool edge preparation process is set up through the discrete element software EDEM. The effects of the speed, the preparation time, the abrasive mesh, the abrasive ratio, the rotation direction on the abrasive state, the abrasive velocity, the cumulated energy, the wear and the action force are investigated. In this paper, the basis for the edge preparation optimization is provided and the importance of the high speed and high efficiency machining is highlighted.
author_names: Xuefeng Zhao

Pengfei Zheng

Lin He

Meng Tao
title: Cutting edge preparation using the discrete element software EDEM
year: 2020

abstract: ABSTRACT The seismic assessment of archaeological heritages is studied by means of 2D numerical analysis with Discrete Element Method (DEM) The proposed approach is based on a refined discretization that reproduces the effective block masonry pattern and on a routine for carrying out seismic analysis according to either quasi static or dynamic approaches. The applicability of the DEM for the analysis of archaeological heritages is discussed referring to the case studies of the south east edge of the external wall of the Colosseum that was restored by Stern in 1807, and the arcades of the Claudio Aqueduct in Rome. The analyses based on DEM provide a reliable estimate of the seismic capacity and a refined representation of the expected failure mode, while also contributing to the design of appropriate strengthening measures. The approach is finally validated through comparison between the outcome of the numerical simulation and the survey of the existing crack pattern of the monuments.
author_names: Anna Mordanova

Gianmarco de Felice
title: Seismic Assessment of Archaeological Heritage Using Discrete Element Method
year: 2020

abstract: Abstract We in this study present a mixed solid shell finite element formulation for laminated shell analysis. With the commonly adopted truncations applied to the strain components and the Jacobian determinant, a generalized stiffness matrix is established. Discrete shear gap (DSG) technique together with assumed natural strain (ANS) method is employed in order to alleviate shear locking and trapezoidal locking. Stiffness matrix formulation is analytically calculated based on the edge based cell backgrounds, which result in simple and efficient computation. The proposed formulation does not require using cross diagonal meshes, which can be an obstacle for several existing three node degenerated shell elements. This aspect makes the present method much more appealing than others through examples tested. Numerical validations show that the present method performs well for both structured and unstructured triangular meshes.
author_names: Leonardo Leonetti

Hung Nguyen-Xuan
title: A mixed edge based smoothed solid shell finite element method (MES FEM) for laminated shell structures
year: 2019

abstract: The aim of this paper is to develop a virtual element method for the two dimensional Steklov eigenvalue problem. We propose a discretization by means of the virtual elements presented in [L. Beirao da Veiga et al. Basic principles of virtual element methods, Math. Models Methods Appl. Sci.23 (2013) 199 214] Under standard assumptions on the computational domain, we establish that the resulting scheme provides a correct approximation of the spectrum and prove optimal order error estimates for the eigenfunctions and a double order for the eigenvalues. We also prove higher order error estimates for the computation of the eigensolutions on the boundary, which in some Steklov problems (computing sloshing modes, for instance) provides the quantity of main interest (the free surface of the liquid) Finally, we report some numerical tests supporting the theoretical results.
author_names: Felipe Lepe

David Mora

Gonzalo Rivera

Ivan G Velasquez
title: A virtual element method for the Steklov eigenvalue problem allowing small edges
venue: ArXiv
year: 2020

abstract: MFEM is an open source, lightweight, flexible and scalable C+ library for modular finite element methods that features arbitrary high order finite element meshes and spaces, support for a wide variety of discretization approaches and emphasis on usability, portability, and high performance computing efficiency. MFEM's goal is to provide application scientists with access to cutting edge algorithms for high order finite element meshing, discretizations and linear solvers, while enabling researchers to quickly and easily develop and test new algorithms in very general, fully unstructured, high order, parallel and GPU accelerated settings. In this paper we describe the underlying algorithms and finite element abstractions provided by MFEM, discuss the software implementation, and illustrate various applications of the library.
author_names: Robert W Anderson

Julian Andrej

Andrew T Barker

Jamie A Bramwell

Sylvain Camier

Jakub Cerveny

Veselin A Dobrev

Yohann Dudouit

Aaron C Fisher

Tzanio V Kolev

Will Pazner

Mark Stowell

Vladimir Z Tomov

Johann P S Dahm

David Medina

Stefano Zampini
title: MFEM: a modular finite element methods library
venue: Comput. Math. Appl.
year: 2021